Screen brightness control method and device and terminal equipment

Abstract

The invention provides a screen brightness control method and device and terminal equipment. The screen brightness control method comprises the following steps: firstly, determining a first brightness value corresponding to a current brightness adjustment gear of a screen; then a first input gray-scale value corresponding to the first brightness value is determined based on a preset Gamma correction lookup table, and the Gamma correction lookup table is the Gamma correction relation between the brightness value of the screen and the initial input gray-scale value of the screen under the specified level of brightness adjustment; and finally, controlling the display brightness value of the screen according to the first input gray-scale value. According to the invention, correct brightness display can be carried out during brightness adjustment, and less hardware resources are occupied.

Description

[0001] This application is a divisional application. The application number of the original application is 201810438207.5, and the original application date is May 9, 2018. The entire contents of the original application are incorporated into this application by reference. Technical Field

[0002] The present application relates to the field of display display, and in particular to a method, device and terminal equipment for controlling screen brightness. Background Art

[0003] Organic light-emitting diode display devices are the main development direction of the next generation of mobile phone panels due to their advantages such as self-luminescence, thin thickness, high contrast, and wide viewing angle. Among them, active-matrix organic light emitting diode (AMOLED) has become the focus of development due to its good flexibility.

[0004] At present, when the display brightness of the screen changes, in order to display the image normally at the current brightness of the screen, it is necessary to adjust the display input data so that the display input data adapts to the current brightness of the screen. In an existing brightness control method, the brightness adjustment range of the screen is divided into multiple different brightness adjustment points, and each brightness adjustment point is configured with an independent corresponding relationship, which can represent the mapping relationship between the original display input data of the screen and the display input data corresponding to the brightness of the segment, and is usually stored in the form of a lookup table. The lookup table for each brightness adjustment point can be regarded as an independent memory or register. When the brightness of the screen is adjusted to a certain brightness adjustment point, the corresponding display input data can be obtained through the lookup table corresponding to the brightness adjustment point, and finally the line output data is obtained through gamma correction to output the screen.

[0005] However, in the prior art, each existing corresponding relationship needs to go through an independent measurement process to be obtained, and multiple corresponding relationships need to be stored in multiple memories, which is costly; and if the current brightness of the screen is not at the existing brightness adjustment point, it is necessary to obtain the corresponding display input data through linear interpolation and other means, resulting in inaccurate brightness display of the panel. Summary of the invention

[0006] The present application provides a screen brightness control method, device and terminal device, which can display the brightness correctly when adjusting the brightness and occupy less hardware resources.

[0007] In a first aspect, the present application provides a method for controlling screen brightness, comprising first determining a first brightness value corresponding to a current brightness adjustment level of the screen; then determining a first input grayscale value corresponding to the first brightness value based on a preset Gamma correction lookup table, the Gamma correction lookup table being a Gamma correction relationship between the brightness value of the screen and an initial input grayscale value of the screen at a specified brightness adjustment level; finally, controlling the display brightness value of the screen according to the first input grayscale value.

[0008] In this way, when adjusting the brightness of the screen, the corresponding relationship between the brightness value and the input grayscale value at other gears of the brightness adjustment can be obtained by relying on the gamma correction relationship between the brightness value and the input grayscale value at the specified gear of the brightness adjustment. Therefore, gamma correction can be implemented for the brightness of the screen display at other gears of the brightness adjustment based on the gamma correction relationship at the specified gear, without having to store the gamma correction relationships at other gears, effectively saving hardware resources.

[0009] Optionally, the screen includes an uneven Mura area. If the brightness values ​​corresponding to each pixel of the screen at the initial brightness adjustment level are all second brightness values, before determining the first brightness value corresponding to the screen at the current brightness adjustment level, the method also includes: before demuraing the screen, determining a second input grayscale value corresponding to the second brightness value based on a preset gamma correction lookup table; and then controlling the display brightness values ​​of each pixel of the screen according to the second input grayscale value.

[0010] In this way, before demura is performed on the screen, gamma correction is performed on the screen containing the mura area, and gamma correction is performed on the screen after demura operation during the brightness adjustment process. This can not only ensure the uniformity of the screen, but also enable the screen to always achieve correct brightness display during the brightness adjustment process. In addition, the gamma correction before demura is based on the same gamma correction lookup table in the brightness adjustment process, which can achieve better hardware integration, save storage space, and reduce hardware costs.

[0011] Optionally, the gamma correction lookup table includes any one of the following: multiple discrete grayscale values ​​and multiple display brightness values, the number of grayscale values ​​is equal to the number of display brightness values, the grayscale values ​​correspond one-to-one to the display brightness values, and the number of discrete grayscale values ​​is equal to the total number of grayscale values ​​of the screen; or, multiple discrete grayscale values ​​and multiple display brightness values, the number of grayscale values ​​is equal to the number of display brightness values, the grayscale values ​​correspond one-to-one to the display brightness values, and the number of discrete grayscale values ​​is less than the total number of grayscale values ​​of the screen.

[0012] In this way, the current hardware can be used to store and express the correspondence between a finite number of integer grayscale values ​​and the corresponding display brightness values, which can not only more accurately represent the correspondence between the input grayscale value and the display brightness value, but also save hardware resources such as memory space or processing power.

[0013] Optionally, the two-dimensional coordinate points formed by the discrete grayscale values ​​and the display brightness values ​​corresponding to any of the discrete grayscale values ​​are all located on a Gamma curve, wherein the abscissa of the Gamma curve represents the grayscale value, and the ordinate of the Gamma curve represents the display brightness value. In this way, each discrete grayscale value and the corresponding display brightness value can satisfy the Gamma curve, so that the brightness is correctly displayed.

[0014] Optionally, the current brightness value of the screen at the current gear and the previous brightness value of the previous gear of the brightness adjustment meet a preset condition, wherein the current brightness value and the previous brightness value correspond to the same input grayscale value, and the preset condition is: the ratio of the brightness value difference of adjacent gears to the previous brightness value satisfies Weber's law. The brightness value difference is the difference between the current brightness value and the previous brightness value. In this way, when the screen implements brightness adjustment, the light and dark changes of the screen can be evenly transitioned, so that the human eye can adapt better.

[0015] Optionally, the maximum brightness value supported by the screen at the specified level is greater than the maximum brightness value supported by the screen at the current level of brightness adjustment. In this way, no matter which level the screen brightness adjustment level is adjusted to, the brightness value corresponding to the pixel at that level will be included in the gamma correction relationship between the pixel display brightness value and the input grayscale value at the specified level of the screen.

[0016] Optionally, specify the maximum level supported when adjusting screen brightness.

[0017] Optionally, determining the input grayscale value corresponding to the brightness value based on a preset Gamma correction lookup table specifically includes: first determining the initial input grayscale value corresponding to the screen when the brightness value displayed on the screen is the brightness value corresponding to the current level of the brightness adjustment; and then replacing the initial input grayscale value with the input grayscale value determined based on the Gamma correction lookup table as the input grayscale value corresponding to the brightness value.

[0018] Optionally, the correspondence between multiple grayscale values ​​and multiple display brightness values ​​in the Gamma correction lookup table conforms to the Gamma correction formula, wherein the display brightness value is the input of the Gamma correction formula, and the grayscale value is the output of the Gamma correction formula. Determining the input grayscale value corresponding to the brightness value based on the preset Gamma correction lookup table specifically includes: calculating multiple grayscale values ​​corresponding to the multiple display brightness values ​​based on the multiple display brightness values ​​and the Gamma correction formula. In this way, only one set of preset Gamma correction lookup tables is needed to determine the Gamma correction lookup table corresponding to the screen at different reference brightness values, saving storage space and reducing hardware costs; and because the set of discrete values ​​includes the correspondence between all integer grayscale values ​​and the corresponding display brightness values, the input grayscale value determined is more accurate, and the screen brightness adjustment is also more accurate.

[0019] Optionally, the gamma correction formula is: f = B 1 / γ *(N-1).

[0020] Among them, f is the grayscale value corresponding to the first brightness value at the current gear of the brightness adjustment after normalization, γ is the Gamma value in the preset Gamma correction lookup table, and N is the total number of grayscales.

[0021] Optionally, when the first brightness value at the current gear of the brightness adjustment is not included in the Gamma correction lookup table, determining the first input grayscale value corresponding to the first brightness value based on the preset Gamma correction lookup table includes: first obtaining the display brightness value in the Gamma correction lookup table that is closest to the first brightness value at the current gear of the brightness adjustment; and then taking the grayscale value corresponding to the display brightness value that is closest to the first brightness value at the current gear of the brightness adjustment as the first input grayscale value corresponding to the first brightness value.

[0022] Optionally, when the calculated grayscale value is not a decimal, the method further includes rounding the calculated grayscale value, and using the rounded result as the first input grayscale value corresponding to the displayed first brightness value.

[0023] Optionally, when the first brightness value at the current gear of the brightness adjustment is not included in the Gamma correction lookup table, determining the input grayscale value corresponding to the screen brightness value based on the preset Gamma correction lookup table specifically includes: first determining two display brightness values ​​directly adjacent to the first brightness value at the current gear of the brightness adjustment based on the Gamma correction lookup table; then establishing a linear interpolation equation based on the two directly adjacent display brightness values ​​and their corresponding grayscale values; finally, obtaining the first input grayscale value corresponding to the first brightness value according to the linear interpolation equation and the first brightness value at the current gear of the brightness adjustment.

[0024] In this way, only one set of preset Gamma correction lookup tables is needed to determine the corresponding Gamma correction lookup tables for the screen under different brightness adjustment levels, which saves storage space and reduces hardware costs. Moreover, the preset Gamma correction lookup table used only includes a limited number of corresponding relationships between input grayscale values ​​and display brightness values, while the other corresponding relationships included in the preset Gamma correction lookup table are obtained through simple linear interpolation operations. While achieving higher grayscale value input accuracy, the calculation speed is faster and the processor overhead is smaller.

[0025] Optionally, before determining a first brightness value displayed by the screen at a current brightness adjustment level, the method further includes receiving a brightness adjustment signal, where the brightness adjustment signal is used to instruct to adjust the display brightness of the screen to the current brightness adjustment level.

[0026] In the second aspect, the present application also provides a device for controlling screen brightness, including: a brightness determination module, used to determine a first brightness value corresponding to the current brightness adjustment level of the screen; a first gamma correction module, used to determine a first input grayscale value corresponding to the first brightness value based on a preset gamma correction lookup table, the gamma correction lookup table being a gamma correction relationship between the brightness value of the screen and the initial input grayscale value of the screen at a specified brightness adjustment level; and a brightness adjustment module, used to control the display brightness value of the screen according to the first input grayscale value.

[0027] In this way, when adjusting the brightness of the screen, the corresponding relationship between the brightness value and the input grayscale value at other gears of the brightness adjustment can be obtained by relying on the gamma correction relationship between the brightness value and the input grayscale value at the specified gear of the brightness adjustment. Therefore, gamma correction can be implemented for the brightness of the screen display at other gears of the brightness adjustment based on the gamma correction relationship at the specified gear, and there is no need to store the gamma correction relationships at other gears, thereby effectively saving hardware resources.

[0028] Optionally, the screen includes an uneven Mura area. If the brightness values ​​corresponding to each pixel of the screen at the initial brightness adjustment level are all second brightness values, the device also includes: a second Gamma correction module, which is used to determine, based on a preset Gamma correction lookup table, a second input grayscale value corresponding to the brightness value displayed by the screen at the initial level as the second brightness value before demodulating the screen; the second Gamma correction module is also used to control the display brightness of each pixel of the screen according to the second input grayscale value; in addition, the device also includes a Mura correction module, which is used to demodulate the screen.

[0029] In this way, before demura is performed on the screen, gamma correction is performed on the screen containing the mura area, and gamma correction is performed on the screen after demura operation during the brightness adjustment process. This can not only ensure the uniformity of the screen, but also enable the screen to always achieve correct brightness display during the brightness adjustment process. In addition, the gamma correction before demura is based on the same gamma correction lookup table in the brightness adjustment process, which can achieve better hardware integration, save storage space, reduce hardware costs, and have better hardware integration.

[0030] Optionally, the gamma correction lookup table includes any one of the following: multiple discrete grayscale values ​​and multiple display brightness values, the number of grayscale values ​​is equal to the number of display brightness values, the grayscale values ​​correspond one-to-one to the display brightness values, and the number of discrete grayscale values ​​is equal to the total number of grayscale values ​​of the screen; or, multiple discrete grayscale values ​​and multiple display brightness values, the number of grayscale values ​​is equal to the number of display brightness values, the grayscale values ​​correspond one-to-one to the display brightness values, and the number of discrete grayscale values ​​is less than the total number of grayscale values ​​of the screen.

[0031] In this way, the current hardware can be used to store and express the correspondence between a finite number of integer grayscale values ​​and the corresponding display brightness values, which can not only more accurately represent the correspondence between the input grayscale value and the display brightness value, but also save hardware resources such as memory space or processing power.

[0032] Optionally, two-dimensional coordinate points formed by discrete grayscale values ​​and display brightness values ​​corresponding to any of the discrete grayscale values ​​are all located on a Gamma curve, wherein the abscissa of the Gamma curve represents the grayscale value, and the ordinate of the Gamma curve represents the display brightness value.

[0033] Optionally, the current brightness value of the screen at the current level and the previous brightness value at the previous level of brightness adjustment meet a preset condition, wherein the current brightness value and the previous brightness value correspond to the same input grayscale value, and the preset condition is: the ratio of the brightness value difference of adjacent levels to the previous brightness value satisfies Weber's law, wherein the brightness value difference is the difference between the current brightness value and the previous brightness value. In this way, when the screen implements brightness adjustment, the brightness and darkness changes of the screen can be evenly transitioned, so that the human eye can adapt better.

[0034] Optionally, the maximum brightness value supported by the screen at the specified level is greater than the maximum brightness value supported by the screen at the current level of brightness adjustment. In this way, no matter which level the screen brightness adjustment level is adjusted to, the brightness value corresponding to the pixel at that level will be included in the gamma correction relationship between the pixel display brightness value and the input grayscale value at the specified level of the screen.

[0035] Optionally, specify the maximum level supported for brightness adjustment.

[0036] Optionally, the first Gamma module is specifically used to: first determine the initial input grayscale value of the screen when the brightness value displayed on the screen is the first brightness value corresponding to the current brightness adjustment level; and then replace the initial input grayscale value with the input grayscale value determined based on the Gamma correction lookup table as the first input grayscale value corresponding to the first brightness value.

[0037] Optionally, the correspondence between multiple grayscale values ​​and multiple display brightness values ​​in the Gamma correction lookup table conforms to the Gamma correction formula, wherein the display brightness value is the input of the Gamma correction formula and the grayscale value is the output of the Gamma correction formula; and the control device also includes: a Gamma correction lookup table acquisition module, which is specifically used to calculate multiple grayscale values ​​corresponding to the multiple display brightness values ​​based on the multiple display brightness values ​​and the correction formula.

[0038] In this way, only one set of preset gamma correction lookup tables is needed to determine the corresponding gamma correction lookup tables for different brightness adjustment levels of the screen, saving storage space and reducing hardware costs; and because this set of discrete values ​​includes the correspondence between all integer grayscale values ​​and the corresponding display brightness values, the determined input grayscale values ​​are more accurate and the screen brightness adjustment is also more accurate.

[0039] Optionally, the gamma correction formula is: f = B 1 / γ *(N-1); wherein f is the first input grayscale value corresponding to the first brightness value at the current gear of the normalized brightness adjustment, γ is the Gamma value in the preset Gamma correction lookup table, and N is the total number of grayscales.

[0040] Optionally, when the first brightness value at the current gear of the brightness adjustment is not included in the Gamma correction lookup table, the first Gamma correction module is also used to: first obtain the display brightness value in the Gamma correction lookup table that is closest to the first brightness value at the current gear of the brightness adjustment; and then use the grayscale value corresponding to the display brightness value that is closest to the first brightness value at the current gear of the brightness adjustment as the first input grayscale value corresponding to the first brightness value.

[0041] Optionally, when the first brightness value at the current gear of the brightness adjustment is not included in the Gamma correction lookup table, the first Gamma correction module is specifically used to: first determine two display brightness values ​​directly adjacent to the first brightness value at the current gear of the brightness adjustment based on the Gamma correction lookup table; then establish a linear interpolation equation based on the two directly adjacent display brightness values ​​and their corresponding grayscale values; finally, obtain a first input grayscale value corresponding to the first brightness value according to the linear interpolation equation and the first brightness value at the current gear of the brightness adjustment.

[0042] In this way, the current hardware can be used to store and express the correspondence between a finite number of integer grayscale values ​​and the corresponding display brightness values, which can not only more accurately represent the correspondence between the input grayscale value and the display brightness value, but also save hardware resources such as memory space or processing power.

[0043] In a third aspect, the present application provides a terminal device, the terminal device comprising: a processor, a first gamma selector, a first gamma correction controller and a screen. The processor is used to determine a first brightness value corresponding to the screen at a current brightness adjustment level. The first gamma selector is used to determine a first input grayscale value corresponding to the first brightness value based on a preset gamma correction lookup table, the gamma correction lookup table being a gamma correction relationship between the brightness value of the screen and the initial input grayscale value of the screen at a specified level of brightness adjustment. The first gamma correction controller is used to control the display brightness value of the screen according to the first input grayscale value.

[0044] In this way, when adjusting the brightness of the screen, the corresponding relationship between the brightness value and the input grayscale value at other gears of the brightness adjustment can be obtained by relying on the gamma correction relationship between the brightness value and the input grayscale value at the specified gear of the brightness adjustment. Therefore, gamma correction can be implemented for the brightness of the screen display at other gears of the brightness adjustment based on the gamma correction relationship at the specified gear, and there is no need to store the gamma correction relationships at other gears, thereby effectively saving hardware resources.

[0045] Optionally, the screen includes an uneven Mura area. If the brightness values ​​corresponding to each pixel of the screen at the initial brightness adjustment level are all second brightness values, the terminal device also includes a second Gamma selector and a second Gamma correction controller; the second Gamma selector is used to determine a second input grayscale value corresponding to the second brightness value based on a preset Gamma correction lookup table before Demura is performed on the screen; the second Gamma correction controller is also used to control the display brightness values ​​of each pixel of the screen according to the second input grayscale value.

[0046] In this way, before demura is performed on the screen, gamma correction is performed on the screen containing the mura area, and gamma correction is performed on the screen after demura operation during the brightness adjustment process. This can not only ensure the uniformity of the screen, but also enable the screen to always achieve correct brightness display during the brightness adjustment process. In addition, the gamma correction before demura is based on the same gamma correction lookup table in the brightness adjustment process, which can achieve better hardware integration, save storage space, reduce hardware costs, and have better hardware integration.

[0047] Optionally, the terminal device also includes a memory for storing a preset Gamma correction lookup table.

[0048] Optionally, the gamma correction controller includes: a voltage generator and a brightness controller, the voltage generator is used to generate a reference voltage according to an input grayscale value; the brightness controller is used to control the screen to display a display brightness value corresponding to the input grayscale value based on the reference voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a flowchart of a method for controlling screen brightness provided in an embodiment of the present application;

[0050] Figure 2 This is a schematic diagram of the Gamma curve under different brightness adjustment levels;

[0051] Figure 3 It is a schematic diagram of a process for determining a first input grayscale value corresponding to a first brightness value at a current gear of brightness adjustment provided by an embodiment of the present application;

[0052] Figure 4 It is a schematic diagram of a Gamma curve corresponding to a Gamma correction lookup table in a method for controlling screen brightness provided in an embodiment of the present application;

[0053] Figure 5 is a flow chart of another method for controlling screen brightness provided in an embodiment of the present application;

[0054] Figure 6 is a structural schematic diagram of a screen brightness control device provided in an embodiment of the present application;

[0055] Figure 7 is a structural schematic diagram of another screen brightness control device provided in an embodiment of the present application;

[0056] Figure 8 It is a schematic diagram of the hardware structure of a terminal device provided in an embodiment of the present application;

[0057] Fig. 9It is a schematic diagram of the hardware structure of another terminal device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0058] When the screen is displaying, due to the inconsistency of the sensitivity of the human eye to different brightness, or the photoelectric characteristics of the screen itself, the brightness of the image displayed on the screen is usually not consistent with the original brightness of the original input image, but there is a certain deviation. At this time, the image output by the screen will be distorted compared with the input image, resulting in a large difference between the color of the screen display and the color of the input image, or the screen displays the image too bright or too dark. Exemplarily, when the color displayed on the screen changes from black to white, the grayscale value input to the screen also changes, but this change is not linear. The physical characteristics of the screen display determine that if the input grayscale value changes linearly, the output brightness value is not linear. In order to ensure that there is no deviation between the displayed brightness value and the brightness value that the screen wants to present, it is necessary to correct the grayscale value input to the screen, that is, to perform a Gamma correction process on the screen so that it displays the desired brightness. Among them, performing Gamma correction on the screen can make the change relationship between the grayscale value input to the screen and the output brightness satisfy a corresponding relationship curve, which is the Gamma curve. When the screen input grayscale value and output brightness value satisfy the Gamma curve, the screen can display the preset brightness and color.

[0059] When using the Gamma curve to calibrate the brightness of the screen, when the overall brightness of the screen changes, or the input and output characteristics of individual pixels on the screen change, it will affect the overall display of the screen brightness. Therefore, the screen brightness needs to be calibrated to make it display normal brightness.

[0060] Figure 1 1 is a flow chart of a method for controlling screen brightness provided in the first embodiment of the present application. Figure 1 As shown, the screen brightness control method provided in this embodiment may specifically include the following steps:

[0061] S101. Determine a first brightness value corresponding to a current brightness adjustment level of a screen.

[0062] Specifically, in order to adapt to different application scenarios, the screen can optionally have multiple different gears for adjusting the brightness. The range of brightness values ​​that can be displayed on the screen is different under different brightness adjustment gears. The following is an example of the brightness adjustment gear of the screen. The maximum brightness value that the screen itself can display is 500 nits. If the screen has 5 different brightness adjustment gears, the first brightness adjustment gear, the range of brightness values ​​that can be displayed on the screen is 0-100nit, and the second brightness adjustment gear, the range of brightness values ​​that can be displayed on the screen is 0-100nit. The range of brightness values ​​is 0-200nit, ..., the range of brightness values ​​that can be displayed on the screen under the fifth brightness adjustment level is 0-500nit. Correspondingly, the 5 brightness adjustment levels of the screen can correspond to the 5 scales on the brightness bar of the screen. For example, the rightmost scale on the screen brightness bar corresponds to the fifth brightness adjustment level, and one scale to the left corresponds to the fourth brightness adjustment level. By analogy, the leftmost scale on the screen brightness bar corresponds to the first brightness adjustment level (that is, the displayable brightness range is the smallest and the screen brightness is also the darkest). Corresponding to different levels for adjusting brightness, when the original image of the screen displays a fixed light and dark relationship, the brightness values ​​corresponding to the areas of the same brightness will also change accordingly. It should be understood that the data listed above are only examples of the levels of brightness adjustment of the screen, and do not limit the levels of brightness adjustment of the screen and the corresponding range of displayable brightness values.

[0063] Since the image is displayed based on the relative light and dark relationship between the pixels in the screen, when the screen brightness is adjusted to different levels, based on the same displayed image, the pixels on the screen will still maintain the same light and dark ratio, so that the entire displayed image can maintain the original texture and pattern and other screen features when the reference brightness value changes. Specifically, when the screen brightness adjustment level changes, the brightness value displayed by each pixel at this level will also change along with the change in level. In an optional situation, there is a positive correlation between the screen brightness adjustment level and the brightness value displayed by each pixel, so that the image can complete the overall light and dark adjustment without damaging the details of the image itself, such as the pattern and texture. Therefore, when the brightness is adjusted to the current level, the first brightness value corresponding to each pixel on the screen at the current level can be determined.

[0064] Since each pixel on the screen is independent of each other, the brightness value of each pixel is also independent of each other, and will only change with the change of the brightness adjustment level of the screen. Therefore, when the screen is at a certain brightness adjustment level, such as the current brightness adjustment level, each pixel on the screen will have an independent first brightness value, and when the screen displays different images, the brightness values ​​displayed by each pixel may be the same or different. Specifically, when displaying the same image, if the brightness adjustment level of the screen is adjusted, the brightness value displayed when the grayscale value input to the screen is the largest can be determined first, and the display brightness value adjusted to each pixel to display other grayscale values ​​can be determined based on a specific ratio or other positive correlation. It is easy to understand that the first brightness value displayed by each pixel point can be positively correlated with the brightness adjustment level of the screen, that is, the first brightness value will change in the same direction as the change direction of the display brightness adjustment level of the screen. When the level of the screen changes from the level representing a darker picture to the benchmark representing a brighter picture, the first brightness value of each pixel point will increase accordingly; and when the level of the screen brightness adjustment changes from the level representing a brighter picture to the level representing a darker picture, the first brightness value of each pixel point will decrease accordingly.

[0065] S102. Determine a first input grayscale value corresponding to a first brightness value based on a preset gamma correction lookup table, wherein the gamma correction lookup table is a gamma correction relationship between a brightness value of a screen and an initial input grayscale value of the screen at a specified level of brightness adjustment.

[0066] Specifically, when the screen is displaying, when a certain grayscale value is input to a pixel, a certain brightness value will be displayed accordingly by applying different driving voltages, so that the image can be displayed normally on the screen. When the screen is displaying, due to the sensitivity of the human eye or the photoelectric characteristics of the screen itself, there will be distortion between the image output by the screen and the input image, for example, the color of the screen display is very different from the color of the input image, or the brightness of the screen display is different from the original brightness of the input image. In order to avoid the deviation between the brightness value displayed on the screen and the brightness value of the original image, it is necessary to correct the grayscale value input to the screen; optionally, the grayscale value input of the screen can be changed by changing the voltage input to the screen, and optionally, the voltage input to the screen can be corrected so that the brightness value of the image displayed on the screen is equal to or linearly related to the brightness value of the actual input image.

[0067] In an optional case, in order to avoid this distortion phenomenon, gamma correction can be performed on the relationship between the output brightness value of the screen display and the input grayscale value of the screen, so as to adjust the response curve between the screen input and output to correct the brightness deviation of the image actually displayed on the screen.

[0068] Among them, when the screen is at a certain brightness adjustment level, the Gamma correction relationship between the brightness value displayed by any pixel point on the screen and the input grayscale value can be either continuous or discrete. For example, when the screen is at a certain brightness adjustment level, the corresponding relationship between the brightness value displayed by any pixel point and the input grayscale value will follow the same response curve, that is, the Gamma curve. At this time, the Gamma curve can be used to represent the corresponding relationship between the brightness value displayed by the pixel point and the input grayscale value at this level, thereby forming a Gamma correction relationship between the brightness value and the input grayscale value. Exemplarily, the abscissa of the Gamma curve can represent the input grayscale value, and the ordinate of the Gamma curve can represent the displayed brightness value. At this time, no matter which brightness the pixel point displays, its corresponding input grayscale value can be found on the Gamma curve. In this way, the brightness value displayed by the pixel point and the corresponding input grayscale value are both continuous and uninterrupted. When it is necessary to obtain the corresponding input grayscale value according to the brightness value displayed by the pixel point, the corresponding accurate input grayscale value can be found.

[0069] However, due to hardware constraints such as storage space and panel accuracy, the grayscale value input on the screen panel is usually a discrete positive integer. Therefore, the correspondence between the brightness value displayed by the screen pixel and the input grayscale value is often not a continuous curve, but a number of discrete points on the Gamma curve. Therefore, the correspondence between the brightness value displayed by the pixel and the input grayscale value under a certain brightness adjustment level can be represented by a set of discrete data. Among them, each brightness value and its corresponding input grayscale value can be represented as a discrete point on the above-mentioned Gamma curve, that is, the two-dimensional coordinate points formed by the discrete grayscale value and the display brightness value corresponding to the grayscale value are all located on the Gamma curve. Here, for example, the grayscale value can still be used as the horizontal coordinate of the Gamma curve, and the displayed brightness value can be used as the vertical coordinate of the Gamma curve. Among them, the number of discrete points in the group of data can be the total number of grayscale values ​​that the screen can display. For example, when the screen is an 8-bit grayscale input, the grayscale value that the screen can display is any integer in the range of 0-255, a total of 256. At this time, the preset corresponding relationship can store 256 groups of discrete data, corresponding to 256 discrete points on the Gamma curve, and when the screen is a 10-bit grayscale input, the grayscale value that the screen can display is any integer in the range of 0-1023, a total of 1204. At this time, the preset Gamma correction relationship can store 1024 groups of discrete data, corresponding to 1024 discrete points on the Gamma curve. Exemplarily, the data format in the preset Gamma correction relationship can be (Code0, Lum), where Code0 is the grayscale value input by the pixel point, corresponding to the horizontal coordinate of the Gamma curve, and Lum is the brightness value displayed when the grayscale value input by the pixel point is Code0, corresponding to the vertical coordinate of the Gamma curve. In this way, the input grayscale value corresponding to the known brightness value can be obtained according to the Gamma correction relationship, or the corresponding display brightness value can be obtained according to the known grayscale value. In addition, when the input grayscale value of the screen pixel is a discrete integer value, the number of grayscale values ​​becomes a finite value, so the number of corresponding relationships between the displayed brightness value and the input grayscale value under a certain brightness adjustment gear will also be finite, such as 256 (corresponding to 8 bits) or 1024 (corresponding to 10 bits), etc.; in this way, the current hardware can be used to store and express the corresponding relationship between a finite number of integer grayscale values ​​and the corresponding display brightness values, which can not only more accurately represent the corresponding relationship between the input grayscale value and the display brightness value, but also save hardware resources such as memory space or processing power.

[0070] In an optional case, the preset Gamma correction relationship only includes some grayscale values ​​and their corresponding brightness values ​​among all grayscale values ​​that can be displayed on the screen. For example, for an 8-bit screen, the preset Gamma correction relationship may only include 30 groups of Gamma correction relationships between input grayscale values ​​and display brightness values. Other grayscale values ​​and corresponding brightness values ​​outside the 30 groups can be obtained by using the Gamma correction relationship between the existing brightness values ​​and grayscale values ​​in the group of data. Specifically, the remaining part of the Gamma correction relationship can be obtained by interpolation calculation and other means. Compared with the method of including all Gamma correction relationships in discrete data, since the number of Gamma correction relationships is small, the required hardware resources are further reduced, and the difference calculation and other means can be used to obtain results close to the actual corresponding relationship, so as to achieve a more accurate correction effect.

[0071] When performing gamma correction, a variety of methods can usually be used to obtain the correct gamma correction relationship between the input grayscale value and the output brightness value of the pixel point when the screen is adjusted to a certain brightness level. In an optional case, in order to perform gamma correction on the screen, a gamma correction lookup table can be used to determine the gamma correction relationship between the screen output brightness and the input grayscale value. The gamma correction lookup table usually stores the initial input grayscale value of the screen and the corresponding screen brightness value, which is actually a mapping table between the initial input grayscale value of the screen and the corresponding screen brightness value. When it is necessary to obtain the input grayscale value corresponding to a specific screen brightness value, or to obtain the brightness value that can be output by a specific grayscale value, it can be obtained through the gamma correction lookup table. Among them, the gamma correction lookup table can usually be obtained in the form of on-site measurement on the production line. Specifically, at the measuring station of the production line, an image generator or other external device can be used to input a certain preset input grayscale value to the screen, and a sampling device can be used to sample and measure the brightness value of the corresponding display on the screen. In this way, different input grayscale values ​​and corresponding display brightness values ​​are measured, so as to establish a one-to-one correspondence between the input grayscale value and the display brightness value one by one, and the obtained correspondence is written into a register or a memory, and arranged in a certain order into a list form, that is, a gamma correction lookup table. When performing gamma correction, the desired input grayscale value or display brightness value can be obtained in the gamma correction lookup table.

[0072] Specifically, the grayscale value input to the screen has different grayscale levels. For example, the input grayscale value can be any value between 0 and 255. For example, each different grayscale input corresponds to a brightness output value. At this time, the relationship between all the input grayscale values ​​of the screen and the corresponding output brightness values ​​can be stored in the gamma correction lookup table. In an optional case, according to different display characteristics of the screen, the grayscale value of the screen can be a different number of bits, such as 8 bits (8bit) or 10 bits (10bit), etc. When the grayscale value of the screen input is 8bit, the pixel points on the screen can have 2 8 = 256 different grayscale values, that is, the grayscale value of the pixel input can be any integer between 0 and 255; optionally, when the grayscale value of the screen input is 10 bits, the pixel of the screen can have 2 10 = 1024 grayscales, and correspondingly, the grayscale value of the pixel input can be any integer between 0 and 1023. Accordingly, the gamma correction lookup table can store the gamma correction relationship between different input grayscale values ​​and output brightness values, so as to find the grayscale input of the pixel according to different brightness output values, and then adjust the parameters such as the voltage of the pixel.

[0073] Optionally, limited by parameters such as hardware storage space, the gamma correction lookup table generally only includes the gamma correction relationship between the initial input grayscale value of the screen and the brightness value displayed on the screen at a brightness adjustment level of the screen. Exemplarily, the gamma correction lookup table can be the gamma correction relationship between the brightness value of the screen and the initial input grayscale value of the screen at a specified brightness adjustment level.

[0074] Among them, the brightness adjustment gear mainly refers to when the screen is in this gear, the initial input grayscale value of the screen will have a certain correspondence with the pre-specified brightness value, so that the entire screen is maintained within a certain brightness level range. When the brightness adjustment gear changes, the same initial input grayscale value corresponding to the pixel point will display different brightness values ​​under the new brightness adjustment gear. In this way, the screen can display the same picture under different brightness states. In an optional case, the Gamma correction lookup table may include two groups of data, and each data in the first group of data has a corresponding data in the second group of data. In this way, the first group of data is the grayscale value input to the screen, and the second group of data is the corresponding display brightness value. The corresponding display brightness value can be found according to the input grayscale value through the Gamma correction lookup table, or the corresponding input grayscale value can be found according to the display brightness value.

[0075] In an optional case, when the screen displays a uniform pure color image, it should be understood that the uniform pure color image is an image with the same pixel value for all pixels, and each pixel in the screen displays the same brightness value, that is, the brightness displayed by each pixel is the same; accordingly, the initial input grayscale value of each pixel is the same. In an optional case, when the screen displays a non-uniform image, different pixels in the screen usually have different grayscale value inputs, thereby presenting the light and dark texture of the image. At this time, different grayscale values ​​will also display different brightness values ​​accordingly, so that different pixels on the screen have different brightness. It should be understood that a non-uniform image is an image with more than one color. Optionally, the non-uniform image can have richer texture features.

[0076] The following is a description of the general process of determining the input grayscale value corresponding to the brightness value of the screen at the specified level of brightness adjustment based on the preset gamma correction lookup table when the screen displays a uniform pure color image, such as a uniform pure white image. For example, assuming that the brightness value currently displayed on the screen is the brightness value corresponding to the maximum grayscale value that the screen can display, at this time, since the screen display is uniform, all pixels on the screen will have the same input grayscale value, and the brightness value displayed by each pixel on the screen is also equal to the brightness value corresponding to the maximum grayscale value, and the brightness bar on the screen for adjusting the screen brightness is located at the maximum scale (for example, it can be located at the rightmost side of the brightness bar). Therefore, the grayscale value input corresponding to the pixel when the brightness value is displayed is determined in the gamma correction lookup table, and the grayscale value found is used as the grayscale value actually input by each pixel on the screen, that is, the grayscale value that each pixel on the screen should have when displaying the brightness value corresponding to the specified level of brightness adjustment, so that the brightness actually displayed on the screen has no deviation from the brightness desired to be displayed. Exemplarily, in the embodiment of the present application, since the screen displays a uniform pure color image, the brightness value displayed by each pixel of the screen is equal under ideal conditions; the initial input grayscale value corresponding to the brightness value output under the ideal condition is determined in the Gamma correction lookup table, and the grayscale value is used as the input of each pixel, so that the actual brightness value displayed by the screen is equal to the brightness value under the ideal condition. In an optional case, the grayscale value input of each pixel can be adjusted by changing the voltage value used to drive each pixel of the screen to emit light, for example, the input voltage of the screen can be increased or decreased to increase or decrease the grayscale value of the pixel input.

[0077] After Gamma correction, the screen can avoid the phenomenon of the image being too dark, too bright or uneven in brightness.

[0078] In an optional case, when the screen displays a non-uniform image, when the brightness displayed by the pixels of the screen is different, the corresponding grayscale value input is also different. In this case, the brightness that each pixel in the screen is expected to display is determined, and the grayscale value input corresponding to the brightness value that each pixel is expected to display is searched in the Gamma correction lookup table, and the grayscale value input found is used as the grayscale value actually input to the screen. Optionally, the driving voltage of the pixel of the screen is controlled so that the grayscale value input to the screen is the grayscale value found in the Gamma correction lookup table. After the screen is Gamma corrected, the brightness value displayed by each pixel of the screen is the same as the brightness value of the input image, and there will be no brightness value deviation, such as the displayed picture appears too dark, too bright, or the brightness is uneven.

[0079] When the brightness adjustment level of the screen changes, the current brightness value of the screen at the current brightness adjustment level and the previous brightness value at the previous brightness adjustment level usually need to meet certain preset conditions, where the current brightness value and the previous brightness value correspond to the same input grayscale value. This can avoid visual discomfort to the human eye due to the obvious change in brightness when the screen is adjusted from the brightness value corresponding to the previously specified level to the brightness value corresponding to the current level of brightness adjustment.

[0080] Specifically, in order to achieve a uniform transition effect of screen brightness changes when the screen brightness is adjusted, as an optional method, the ratio of the brightness value difference between adjacent gears to the previous brightness value satisfies Weber's law (Web-Fechner Law). The brightness value difference is the difference between the current brightness value and the previous brightness value.

[0081] Specifically, when the brightness is adjusted, the brightness of the screen can change within a certain brightness adjustment range. Among them, due to hardware and other limitations, the brightness of the screen is not adjusted smoothly, but the brightness adjustment range is divided into several brightness adjustment points at equal intervals, each brightness adjustment point corresponds to an independent brightness value, and the screen will pass through different brightness adjustment points in sequence when adjusting, so the brightness of the screen will also be displayed in sequence as the brightness values ​​corresponding to different brightness adjustment points. It can be understood that when the brightness adjustment gear of the screen is adjusted from the original brightness adjustment gear, that is, the gear before the brightness adjustment to the current gear of the brightness adjustment, the brightness value of the screen corresponding to the same input grayscale value at two different gears, that is, the current brightness value at the current gear and the previous brightness value of the previous gear can be the brightness value of the two adjacent brightness adjustment points. In this way, if the difference in the brightness value of the screen at two different brightness adjustment gears is too large, then when the screen is adjusted between the two adjacent brightness adjustment points, the difference in the brightness value will be too large, so that the brightness of the screen will show a jump effect, which seriously affects the user's visual experience. According to Weber's law, the difference threshold of human eye perception will change with the change of the original stimulus amount. Therefore, in order to avoid flickering and other phenomena when the screen is adjusted, the brightness change between two adjacent brightness adjustment points needs to be reduced to a level that the human eye will not feel drastic changes, that is, the brightness value difference, that is, the difference between the current brightness value and the previous brightness value, and the ratio between the previous brightness value of the screen in the previous gear of the brightness adjustment is less than a certain threshold. At this time, the size of the brightness value difference between the brightness values ​​of the screen under two different brightness adjustment gears changes with the size of the brightness value of the same grayscale value corresponding to the gear before adjustment. When the brightness value of the screen is large, the brightness of the screen is brighter. At this time, even if the brightness change is large, it is not easy for the naked eye to feel it; when the brightness value of the screen is small, the screen is at a darker brightness. At this time, the naked eye is more sensitive to changes in brightness, so it is necessary to keep a small brightness value difference. Generally, the current brightness value and the previous brightness value are usually the maximum brightness corresponding to the screen at this gear of brightness adjustment.

[0082] Specifically, according to empirical data, the threshold can be 0.017, that is, when the screen realizes brightness adjustment, the ratio between the brightness value difference between two adjacent brightness adjustment points and the previous brightness value of the screen at the previous gear of the brightness adjustment is less than or equal to 0.017, which can make the screen realize a relatively smooth brightness change process when adjusting the brightness, making it difficult for the naked eye to detect the jump of the unit brightness change. For example, when the maximum brightness value corresponding to the gear before the brightness adjustment is L, the ratio between the brightness value difference △L and L is △L / L≤0.017, and the changed brightness value L'=L-△L≥0.983.

[0083] It is understandable that when the screen is adjusting the brightness, it may need to go through several brightness adjustment points to adjust to the desired brightness value, and at this time, the brightness difference between each two adjacent brightness adjustment points should be less than or equal to 0.017 times the brightness value of the same preset grayscale value corresponding to the gear before the brightness adjustment, that is, L N -L N-1 ≤0.017*L N , so that the brightness change between each two brightness adjustment points is not easily felt by the naked eye. In this way, during the entire process of adjusting the screen from the initial brightness to the expected brightness, the naked eye is not easily aware of the drastic change in screen brightness, thus ensuring the user's visual experience.

[0084] When the brightness adjustment level of the screen changes, the brightness displayed by each pixel on the screen changes accordingly. In an optional case, the maximum brightness value that the screen can display at the current brightness adjustment level is 0.983 times the maximum brightness value of the level before the brightness adjustment. Correspondingly, other brightness values ​​that the screen can display are also 0.983 times the brightness values ​​corresponding to the level before the brightness adjustment.

[0085] In order to determine the grayscale value of any pixel on the screen when the brightness adjustment level of the screen changes to any brightness adjustment level, the Gamma correction relationship under a certain brightness adjustment level or the Gamma correction lookup table can be used to determine the grayscale value of any pixel on the screen when the brightness displayed by the pixel is the current brightness adjustment level. Specifically, the maximum brightness value supported by the screen at the specified level can be greater than the maximum brightness value that the screen can display at the current brightness adjustment level. Optionally, the specified level can be the maximum level supported during brightness adjustment. In this way, since the maximum brightness value supported by the screen at the specified level reflects the maximum brightness value that the screen can reach, no matter which level the brightness adjustment level of the screen is adjusted to, the brightness value corresponding to the pixel at the level will be included in the Gamma correction relationship between the brightness value displayed by the pixel at the specified level and the input grayscale value.

[0086] However, when the screen brightness is adjusted to the current level, the same screen hardware is always used for display before and after the brightness adjustment. Therefore, due to the inconsistent sensitivity of the human eye to different brightness or the optoelectronic characteristics of the screen itself, the nonlinear change between the displayed image brightness and the input brightness of the original image (i.e., the grayscale value of the pixel) should still conform to the Gamma curve to ensure that the picture has normal brightness and color. It should be understood that the Gamma curve after the brightness adjustment level is changed is not the same as the Gamma curve before the brightness adjustment. For example, Figure 2As shown in FIG. 1 , the solid line is the Gamma curve before the brightness adjustment gear is changed, and the dotted line is the Gamma curve after the brightness adjustment gear is changed. Figure 2 It can be concluded that when the same grayscale value is input to a pixel (i.e. the same x-coordinate), different brightness values ​​(corresponding to different y-coordinates) will be generated on different gamma curves. However, in theory, when the same grayscale value is input, only the same brightness value can be displayed on the same screen hardware. Therefore, it is necessary to calibrate the gamma correction relationship between the grayscale value input to each pixel on the screen and the displayed brightness value, so that the gamma correction relationship between the grayscale value input and the displayed brightness value at different brightness adjustment levels always conforms to the gamma curve, that is, when the same initial grayscale value is input to the pixel on the screen, different brightness values ​​will be displayed at different brightness adjustment levels. For example, if the grayscale value input by the pixel is 1023, and the brightness value displayed by the pixel is 500nit under the original brightness adjustment gear (the corresponding y coordinate in the solid line is 500), after changing the brightness adjustment gear of the screen, the brightness value displayed when the grayscale value input is 1023 under the adjusted gear of the brightness adjustment needs to be adjusted accordingly, so that the input grayscale value and the displayed brightness value also meet the gamma curve under the adjusted benchmark (corresponding to Figure 2 In an optional case, the adjusted brightness value is 0.983 times the original brightness value. At this time, when the input grayscale value is 1023, the displayed brightness value is 491.5nit (the corresponding y coordinate in the dotted line is 491.5).

[0087] It should be understood that the above only lists the Gamma curves under two different brightness adjustment gears. Figure 2Only two Gamma curves under different brightness adjustment levels are drawn. In actual situations, each brightness adjustment level of the screen will correspond to a different Gamma curve. In order to make the Gamma correction relationship between the grayscale value input by the screen pixel point and the displayed brightness value conform to the Gamma curve under different brightness adjustment levels, it is theoretically necessary to measure the screen under each brightness adjustment level to obtain the Gamma curves corresponding to the different levels and store them in registers or memories respectively. However, this approach will occupy multiple production lines for measurement, occupy measurement resources, and occupy a large amount of storage space, increasing hardware costs. In an embodiment of the present application, only the Gamma curve corresponding to the grayscale value input by the screen pixel point and the displayed brightness value under a specified brightness adjustment level can be measured, and based on the curve, the Gamma curve corresponding to the input grayscale value and the displayed brightness value under other brightness adjustment levels can be calculated, saving production line measurement resources and hardware storage resources. In an optional situation, the gear corresponding to the maximum brightness value that the screen can display can be selected as the designated gear for brightness adjustment, and the Gamma correction relationship between the grayscale value input to the screen and the displayed brightness value can be measured under the brightness adjustment gear to obtain a set of Gamma curves. The Gamma curve includes all brightness values ​​of the screen from the minimum brightness value to the maximum brightness value. After adjusting the gear, the brightness value displayed on the screen will be smaller than the brightness value under the designated gear for brightness adjustment. Therefore, the brightness value displayed on the screen and the corresponding input grayscale value can still be found in the Gamma curve. Therefore, the Gamma curve under the brightness adjustment gear corresponding to the maximum brightness value can be pre-stored in a memory or register. After the brightness adjustment gear is changed, the Gamma curve of the input grayscale value and the displayed brightness value under other brightness adjustment gears is calculated based on the pre-stored Gamma curve to achieve correction of the corresponding relationship between the input grayscale value and the displayed brightness value under other gears.

[0088] Because the corresponding relationship between the brightness value displayed by any pixel on the screen and the input grayscale value can be either continuous or discrete when the screen is at a certain brightness adjustment level. Therefore, when the screen is at a certain brightness adjustment level, the corresponding relationship between the brightness value displayed by any pixel and the input grayscale value can follow the same curve, that is, the above-mentioned Gamma curve. At this time, the Gamma curve can be used to represent the Gamma correction relationship between the brightness value displayed by the pixel and the output grayscale value at the brightness adjustment level. At this time, no matter which brightness the pixel displays, its corresponding input grayscale value can be found on the Gamma curve.

[0089] In addition, when the Gamma correction relationship between the brightness value displayed by the screen pixel and the input grayscale value is limited by hardware and other constraints and cannot be expressed by a continuous curve, the Gamma correction lookup table between the brightness value displayed by the pixel and the input grayscale value under a certain brightness adjustment gear can also be represented by discrete data. Among them, each brightness value and its corresponding input grayscale value can be characterized by a discrete point on the above-mentioned Gamma curve. Specifically, the Gamma correction lookup table may include multiple discrete grayscale values ​​and multiple display brightness values, wherein the number of grayscale values ​​is equal to the number of display brightness values, and the grayscale values ​​correspond to the display brightness values ​​one by one, and the number of discrete grayscale values ​​is equal to the total number of grayscale values ​​of the screen. In this way, the input grayscale value corresponding to the known brightness value can be obtained according to the Gamma correction lookup table, or the corresponding display brightness value can be obtained according to the known grayscale value. Among them, when a certain brightness value is not included in the corresponding relationship represented by the group of discrete data, the existing brightness value and grayscale value can be used, and the input grayscale value corresponding to the brightness value can be obtained by interpolation calculation and other means.

[0090] In addition, when using discrete data to express the Gamma correction relationship between the brightness value displayed by the screen pixel point and the input grayscale value in the Gamma correction lookup table, a set of discrete data is also used for representation, but the set of discrete data only includes some of the corresponding relationships among all the corresponding relationships, and the remaining unknown corresponding relationships among all the corresponding relationships can be obtained by using the corresponding relationship between the existing brightness value and grayscale value in the set of data. Specifically, the Gamma correction lookup table also includes multiple discrete grayscale values ​​and multiple display brightness values. The number of grayscale values ​​and display brightness values ​​is equal and one-to-one corresponding, but the number of discrete grayscale values ​​is less than the total number of grayscale values ​​of the screen. At this time, interpolation calculation and other means can be used to obtain the remaining corresponding relationships. Generally, the partial Gamma correction relationship contained in the set of discrete data is usually discrete points set at equal intervals on the Gamma curve.

[0091] For the sake of explanation, Figure 2Take as an example to illustrate. The solid line is the Gamma curve corresponding to the input grayscale value and the display brightness value under the specified gear of the brightness adjustment measured on the production line. In an optional case, the maximum brightness value that the screen can display is 500nit, so the brightness adjustment gear corresponding to 500nit is selected as the specified gear for brightness adjustment. Since the maximum brightness value of the screen at this time corresponds to the maximum input grayscale value, for example, the grayscale value is 1023, the Gamma curve under the specified gear of the brightness adjustment at this time will satisfy the above-mentioned Gamma correction relationship between the grayscale value 1023 and the brightness value 500nit. After adjusting the brightness adjustment gear, the maximum brightness value that the screen can display becomes 491.5nit. At this time, the Gamma correction relationship between the initial input grayscale value and the display brightness value should be as follows Figure 2 The Gamma curve shown by the dotted line does not actually exist (i.e. it has not been actually measured and is not stored in the memory or register). At this time, it can be observed that the brightness value of 491.5nit after the brightness adjustment is adjusted can find the corresponding input grayscale value in the Gamma curve represented by the solid line, so the grayscale value required to display the brightness value of 491.5nit can be found in the solid line. Figure 2 In the solid line, the input grayscale value corresponding to the displayed brightness value of 491.5nit should be 1015. The found 1015 is used as the actual input grayscale value of the pixel point with an initial input grayscale value of 1023, that is, 1023 is replaced by 1015, and the brightness value displayed under the adjusted gear is 491.5nit.

[0092] It is understandable that the Gamma curve after the brightness adjustment gear changes is not actually measured, nor stored in the memory, but is only obtained through a series of calculations. Optionally, in actual use, it is only necessary to obtain a Gamma correction relationship between a finite number of input grayscale values ​​and display brightness values. In this case, the corresponding relationship between the input grayscale value and the display brightness value is a number of discrete points on the Gamma curve.

[0093] It should be understood that after the brightness adjustment gear changes, the initial input grayscale value of 1023 cannot make the displayed brightness value 491.5nit. For example, the original input image source is a photo of a giant panda, and the input grayscale value of the white fur area of ​​the giant panda is 1023. Before the brightness adjustment gear changes, the white area with the initial input grayscale value of 1023 displays a brightness value of 500nit. After the brightness adjustment gear changes, the brightness value displayed by the white area with the initial input grayscale value of 1023 should become 491.5nit. If no correction is performed, the white area with the initial input grayscale value of 1023 cannot actually display a brightness of 491.5nit. Based on the Gamma curve corresponding to the solid line, it can be obtained that the grayscale value required to output 491.5nit is 1015. At this time, 1015 is input to the pixel points of the screen as the actual grayscale value of the white area in the image source, so that the area with the grayscale value of 1023 in the image source can display a brightness value of 491.5nit. 1023 is the initial input grayscale value of the white area in the image source, and 1015 is the actual input grayscale value of the white area. In an optional case, assuming that the initial input grayscale value is Code0 and the actual input grayscale value is Code1, the function f(.) can be used to characterize the correspondence between the original grayscale value in the image source and the actual input grayscale value, that is, Code1 = f(Code0). Further, the correspondence between the actual input grayscale value Code1 and the displayed brightness value can be characterized by the function G(.). Assuming that the displayed brightness value is Lum, then Lum = G(Code1). It should be understood that Figure 2 The horizontal axis of the Gamma curve shown in is the grayscale value Code0 of the original input of the image source, and the vertical axis is the displayed brightness value Lum. The correspondence between the initial input grayscale value and the displayed brightness value can be represented by a composite function, that is, Lum = G (Code1) = G (f (Code0)). Therefore, after the brightness adjustment gear is changed, first determine the brightness value Lum that needs to be displayed corresponding to the originally input grayscale value Code0, and then obtain the grayscale value Code1 that should be input when the brightness value is Lum before the gear change (for ease of understanding, the brightness adjustment gear of the measured Gamma curve is taken as the gear before the brightness adjustment gear is changed) based on the pre-stored Gamma curve. Code1 is used as the actual input grayscale value of the pixel corresponding to Code0, that is, the first input grayscale value, so that the brightness value displayed by the pixel is Lum, that is, the first brightness value corresponding to the first input grayscale value.

[0094] In this way, it can be determined that when the screen changes the brightness adjustment level and the pixel displays the first brightness value corresponding to the current brightness adjustment level, the corresponding first grayscale value should be the grayscale value that should actually be input to the pixel, that is, Code 1. Since different input grayscale values ​​correspond to different driving voltages, different brightness will be displayed on the screen. Therefore, the voltage used to drive the pixel is not the voltage value corresponding to Code 0, but the voltage value corresponding to Code 1.

[0095] For example, assuming that the screen is 10-bit and always displays a white uniform picture, the brightness values ​​displayed by each pixel on the screen are the same and are equal to the maximum brightness value of the screen at the specified brightness adjustment level, that is, the pixel display brightness is 500nit, and the corresponding input grayscale value is the maximum grayscale value of 1023. When the screen brightness is adjusted, the difference in the screen brightness value when the screen changes from the specified brightness adjustment level to the current level can be a fixed value. For example, the fixed value can be 0.017 times the maximum brightness value before the brightness adjustment level changes, that is, the threshold value of △L=L*0.017. Correspondingly, the brightness adjustment point on the brightness bar on the screen will also move one grid position scale accordingly.

[0096] When the brightness adjustment gear of the screen is changed to the current brightness adjustment gear, the maximum brightness of the screen can be adjusted to 500*(1-0.017)=491.5nit, that is, when the brightness adjustment point moves one scale on the brightness bar, the maximum brightness value of the screen will change from 500nit to 491.5nit. At this time, the initial input grayscale value Code0 of the screen remains unchanged, and the actual corresponding input grayscale value Code1 needs to be changed to other grayscale values ​​to display the corresponding brightness value.

[0097] Specifically, since the gamma correction relationship between the initial input grayscale value and the display brightness value of the screen at a specified brightness adjustment level has been pre-stored in a memory or a register, the gamma correction relationship can be a gamma correction lookup table. Optionally, the gamma correction lookup table can be a continuous gamma curve or a partially discrete point on the gamma curve. Therefore, when the screen is at the current brightness adjustment level, in order to find out the actual input grayscale value that each pixel point should have to display the brightness value corresponding to the current brightness adjustment level, the preset gamma correction lookup table can also be used to obtain the first input grayscale value required for each pixel point on the screen to display the first brightness value corresponding to the current brightness adjustment level.

[0098] S103: Control the display brightness value of the screen according to the first input grayscale value.

[0099] After redetermining the grayscale value that should actually be input for each pixel of the screen in order to display the correct image, the grayscale value can be used as the actual input grayscale value that each pixel of the screen should have in order to display the first brightness value corresponding to the current level of brightness adjustment, that is, the first input grayscale value. When displaying, the original grayscale value of each pixel in the source image is replaced by the actual grayscale value. In this way, after being processed by the preset gamma correction lookup table, the screen display output at the current level of brightness adjustment can be obtained.

[0100] After the above steps, when the screen brightness adjustment gear changes, for example, when the brightness adjustment gear is adjusted from the specified gear to the current gear, as the overall brightness of the screen changes, each pixel on the screen can display a new brightness value, so that the screen can display the image normally under the new overall brightness. In order to make the pixel display a new brightness value, the input grayscale value corresponding to the pixel when displaying the new brightness value can be found based on the previously preset Gamma correction lookup table, and the input grayscale value can be used to replace the initial grayscale value of the source image on the screen, so as to achieve the change of the overall brightness of the image while maintaining the texture and pattern of the source image. In this process, the same Gamma correction lookup table is always used for the Gamma correction process. Compared with the prior art, by pre-storing a plurality of Gamma correction lookup tables corresponding to different screen brightness preset points in the hardware, and calling the corresponding Gamma correction lookup table to perform the Gamma correction process when the screen is adjusted to different brightness, the screen brightness control method in this embodiment can significantly reduce the hardware storage space, thereby reducing the manufacturing cost. In addition, compared with the method of interpolating the gamma correction lookup table corresponding to other brightness values ​​based on several known preset brightness values, the screen brightness method in this embodiment can obtain the corresponding input through calculation through the preset gamma correction lookup table regardless of which brightness adjustment level the screen is adjusted to, and thus has higher correction accuracy.

[0101] In this embodiment, the method for controlling the screen brightness includes first determining the brightness value corresponding to the current gear of the screen brightness adjustment; then determining the input grayscale value corresponding to the brightness value based on a preset gamma correction lookup table, the gamma correction lookup table is the gamma correction relationship between the brightness value of the screen and the initial input grayscale value of the screen at the specified gear of the brightness adjustment; finally, controlling the brightness of the screen according to the input grayscale value. In this way, the corresponding relationship between the brightness value and the input grayscale value at other gears of the brightness adjustment can be obtained by relying on the gamma correction relationship between the brightness value and the input grayscale value at the specified gear of the brightness adjustment, and the gamma correction of the brightness displayed on the screen at other gears of the brightness adjustment can be realized based on the gamma correction relationship at the specified gear, without the need to store the gamma correction relationship at other gears, which effectively saves hardware resources.

[0102] During the brightness correction of the screen, due to the general limitation of hardware, the correspondence between each display brightness value of the screen pixel and the input grayscale value is usually represented by a series of discrete points. Taking the screen as 10 bits (10bit) as an example, there can be a total of 1024 discrete points used to represent the correspondence between the display brightness value and the input grayscale value, and each discrete point corresponds to a grayscale value in the grayscale value 0-1023 and the corresponding display brightness value. In this way, the correspondence between the display brightness value and the input grayscale value can be represented by a gamma correction lookup table, that is, the gamma correction lookup table can include multiple discrete grayscale values ​​and multiple display brightness values, wherein the number of grayscale values ​​is equal to the number of display brightness values, and the grayscale values ​​correspond to the display brightness values ​​one by one, and the number of discrete grayscale values ​​is equal to the total number of grayscale values ​​of the screen. In this way, when executing step S102 in the aforementioned embodiment, when determining the first input grayscale value corresponding to the first brightness value at the current gear of the brightness adjustment based on the preset gamma correction lookup table, the gamma correction relationship represented by these discrete points can be used to obtain the first input grayscale value corresponding to the first brightness value at the current gear of the brightness adjustment.

[0103] In this embodiment, the correspondence between the multiple grayscale values ​​and the multiple display brightness values ​​in the Gamma correction lookup table may conform to the Gamma correction formula, wherein the display brightness value is the input of the Gamma correction formula, and the grayscale value is the output of the Gamma correction formula. Therefore, as an optional implementation, the step of determining the first input grayscale value corresponding to the first brightness value corresponding to the current gear of the brightness adjustment based on the preset Gamma correction lookup table may specifically include the following steps:

[0104] Based on the multiple display brightness values ​​and the Gamma correction formula, multiple grayscale values ​​corresponding to the multiple display brightness values ​​are calculated.

[0105] Specifically, since the grayscale values ​​and display brightness values ​​in the Gamma correction lookup table are both on the Gamma curve, the Gamma correction formula corresponding to the Gamma curve can be used for calculation to obtain the grayscale value corresponding to the display brightness value. Among them, the Gamma correction formula corresponding to the Gamma curve is usually a power function. When obtaining according to the Gamma correction formula, multiple display brightness values ​​of the screen can be obtained first, and multiple grayscale values ​​that should be possessed for displaying each display brightness value can be obtained according to these display brightness values ​​and the Gamma correction formula.

[0106] In the above steps, for different screens, the screens will have different brightness adjustment ranges; for example, the maximum brightness value of the screen can be 500nit or 800nit. Therefore, before using the brightness value displayed by the pixel to obtain the corresponding actual input grayscale value, it is generally possible to eliminate the dimensions of each brightness value, for example, the maximum brightness value of the screen at a specified brightness adjustment level and the maximum brightness value of the screen at a current brightness adjustment level, as well as the absolute value relationship between the first brightness value of the pixel corresponding to the current brightness adjustment level and the brightness value displayed by the pixel at the specified brightness adjustment level can be transformed into a relative value relationship, thereby eliminating the influence of different dimensions, simplifying the calculation process and improving the accuracy of the results.

[0107] Specifically, in order to eliminate the dimension effect of the brightness value, after the brightness adjustment level of the screen is adjusted from the designated level of the brightness adjustment to the current level of the brightness adjustment, the first brightness value corresponding to any pixel point in each pixel at the current level of the brightness adjustment can be normalized. The brightness value after normalization is a dimensionless value, so it can be directly substituted to obtain the relative proportional relationship between the first brightness value of the pixel point at the current level of the brightness adjustment and the brightness value at the designated level.

[0108] Optionally, when normalizing the first brightness value corresponding to the current gear of the brightness adjustment, the normalized brightness value can be obtained according to formula (1).

[0109] F2=F1*B2 / B1(1)

[0110] Among them, F2 is the first brightness value corresponding to the current gear of the brightness adjustment after normalization, and F1 is the brightness value corresponding to the specified gear of the brightness adjustment after normalization, B2 is the maximum brightness value of the screen corresponding to the current gear of the brightness adjustment, and B1 is the maximum brightness value of the screen corresponding to the specified gear of the brightness adjustment.

[0111] Exemplarily, the brightness value corresponding to the specified level of brightness adjustment can be simplified to a dimensionless pure number after normalization, so as to facilitate subsequent calculations.

[0112] For example, the screen can display a pure color image. At this time, when the screen is in a specified brightness adjustment level, the brightness value displayed by each pixel on the screen can be the maximum brightness value of the screen at the specified brightness adjustment level. Specifically, when the maximum brightness value of the screen at the specified brightness adjustment level and the brightness value of each pixel are both 500nit, the brightness value is normalized, and the corresponding brightness value at the specified brightness adjustment level after normalization can be: 500 / 500=1.

[0113] In this way, when the brightness adjustment level of the screen needs to be adjusted to the current brightness adjustment level, for example, when the maximum brightness value of the screen at the current brightness adjustment level can be 491.5 nit, the first brightness value F2 corresponding to the current brightness adjustment level after normalization can be calculated according to the above formula (1): F2 = 1*491.5 / 500 = 0.983.

[0114] Afterwards, the grayscale value corresponding to the first brightness value at the current level of the normalized brightness adjustment can be determined as the first input grayscale value corresponding to any pixel point based on the preset Gamma correction lookup table.

[0115] Specifically, the first brightness value of any pixel in the current brightness adjustment gear is obtained, and normalization is performed to obtain the first brightness value of the current brightness adjustment gear after normalization, that is, 0.983. Then, the grayscale value corresponding to the dimensionless value can be calculated according to the preset Gamma correction lookup table, that is, when the screen is in the current brightness adjustment gear, the corresponding actual input grayscale value that the pixel should have to display the corresponding first brightness value, that is, the first input grayscale value.

[0116] Specifically, the input grayscale value in the gamma correction lookup table is used as the horizontal coordinate, and the corresponding output brightness value is used as the vertical coordinate, and a response curve Y=(X+e) between the input grayscale value and the output brightness value can be obtained. γ , where Y is the output brightness value, X is the input grayscale value, e is the compensation coefficient, and γ is the power value of the curve, also known as the gamma value. This curve is the Gamma curve corresponding to the Gamma correction lookup table. And the relationship between all grayscale values ​​and brightness values ​​in the preset Gamma correction lookup table satisfies the power function relationship. Therefore, the grayscale value corresponding to the second preset brightness value can be obtained through the power function relationship in the Gamma correction lookup table. For example, the curve corresponding to the Gamma correction lookup table is as follows Figure 2 As shown. Among them, Figure 2 The horizontal axis is the input grayscale value, and the vertical axis is the output brightness value. The Gamma correction curve is as follows: Figure 2 Shown by the solid line.

[0117] As an optional method, the step of determining the first input grayscale value corresponding to the first brightness value at the current gear of the brightness adjustment after normalization based on a preset gamma correction lookup table can specifically be performed by first obtaining the first input grayscale value corresponding to the first brightness value at the current gear of the brightness adjustment after normalization according to formula (2).

[0118] f=F2 1 / γ *(N-1) (2)

[0119] Among them, f is the first input grayscale value corresponding to the first brightness value at the current gear of the brightness adjustment after normalization, γ is the Gamma value in the preset Gamma correction lookup table, and N is the total number of grayscales.

[0120] After obtaining f, f can be determined as the input grayscale value corresponding to any pixel point.

[0121] Specifically, the Gamma value in the preset Gamma correction lookup table is the Gamma value of the response curve. In an optional case, γ can be taken as 2.2, etc. It should be understood that the total number of grayscales represents the total number of grayscale values ​​from black to white (corresponding to binary numbers from 0 to 1). For example, when the input grayscale value is 8 bits, there are 256 grayscale values, namely 0-255, wherein the grayscale value 0 corresponds to black, and the grayscale value 255 corresponds to white; when the input grayscale value is 10 bits, there are 1024 grayscale values, wherein the grayscale value 0 corresponds to black, and the grayscale value 1023 corresponds to white. Since different screens usually have different numbers of grayscales, for example, when the input grayscale value is 8 bits, it can have 2 8 = 256 grayscales, while a 10-bit screen can have 2 10 = 1024 gray levels, so the value of N will also vary with different screens. In this embodiment, N = 1024, that is, the screen has a total of 1024 gray levels.

[0122] In addition, as an optional method, since the result calculated by the Gamma correction formula may be a decimal, and the grayscale values ​​stored in the Gamma correction lookup table are all integers. In this way, when the first brightness value at the current gear of the brightness adjustment is not included in the Gamma correction lookup table, the step of determining the first input grayscale value corresponding to the first brightness value based on the preset Gamma correction lookup table can also specifically include: first obtaining the display brightness value in the Gamma correction lookup table that is closest to the first brightness value at the current gear of the brightness adjustment; and then using the grayscale value corresponding to the display brightness value that is closest to the preset brightness value as the first input grayscale value corresponding to the first brightness value.

[0123] Still taking an example to illustrate, after the normalized first brightness value is obtained as 0.983 using formula (1), this value can be substituted into formula (2) for calculation, and f=0.983 can be obtained. 1 / 2.2 *(1024-1)=1015.06, this value contains decimals, and in the existing discrete points used to represent the corresponding relationship between the display brightness value and the input grayscale value, the grayscale value of each discrete point is an integer, so the result is not included in the preset Gamma correction lookup table. At this time, the integer closest to the calculation result can be taken as its corresponding grayscale value, and the display brightness corresponding to the point with this grayscale value can be approximated as the corresponding brightness value under the current gear of the brightness adjustment. Here, since f=1015.06, the integer 1015 closest to the f value can be taken, and 1015 is the first input grayscale value corresponding to the first brightness value under the current gear of the brightness adjustment after normalization, and the point representing the grayscale value 1015 among all discrete points can approximately display the first brightness value under the current gear of the brightness adjustment.

[0124] When the correspondence between the display brightness value and the input grayscale value is represented by a series of discrete points, since each discrete point represents an integer grayscale value, the grayscale value result obtained by these discrete points is closer to the input grayscale value required for the brightness value at the current gear of the actual display brightness adjustment. For example, in the above calculation process, there is only a small error (0.06) between the calculated grayscale value 1015 and the first input grayscale value 1015.06 of the first brightness value at the current gear of the actual display brightness adjustment, that is, less than an integer grayscale value, and when the number of grayscale values ​​in the preset Gamma correction lookup table is large (for example, a 10-bit screen has 1024 different grayscale values), there is only a small difference between the brightness values ​​corresponding to the two adjacent grayscale values, so that the correspondence between the input grayscale value and the display brightness value can be more accurately represented while saving hardware resources such as memory space or processing power.

[0125] For example, in Figure 2 In the example, it is assumed that before the brightness is changed, the screen is displayed at the specified brightness adjustment level. At this time, the maximum brightness value of the screen is 500nit. At this time, the input grayscale value corresponding to the pixel point with a brightness value of 500nit is 1023, and the input grayscale value corresponding to the pixel point with other brightness values ​​under this level can be obtained according to the Gamma curve under this level. For example, when the specified level of the screen brightness adjustment is the level corresponding to the maximum brightness value of 500nit, its corresponding Gamma curve can be as follows: Figure 2 The solid line in the Gamma curve is shown. At this time, the ordinate of point b on the Gamma curve is the brightness value F1 of a certain pixel at the specified brightness adjustment level, which is assumed to be the same as the maximum brightness value of the screen at the specified brightness adjustment level, both of which are 500nit, and the abscissa of point a is the grayscale value corresponding to the brightness value F1 of the pixel at the specified brightness adjustment level, which is easily understood to be 1023, as shown by arrow 1.

[0126] When the brightness adjustment level of the screen is adjusted from the specified level to the current level of the brightness adjustment, at this time, the maximum brightness value is adjusted from 500nit at the specified level of the brightness adjustment to 491.5nit at the current level of the brightness adjustment. Exemplarily, the Gamma curve corresponding to the screen at this time may be the Gamma curve shown by the dotted line; it should be understood that when the brightness adjustment level of the screen changes, the Gamma curve corresponding to the input grayscale value of the pixel point and the displayed brightness value will also change, that is, different references correspond to different Gamma curves. In an embodiment of the present application, there is only one set of Gamma curves. When the brightness adjustment level of the screen changes, it is necessary to obtain the Gamma curves under other reference brightness based on the unique set of Gamma curves, and obtain the input grayscale value corresponding to each brightness value under the corresponding level. At this time, the brightness value of the pixel point will also change accordingly, and become the brightness value F2 under the current level of the brightness adjustment, such as Figure 2 As shown by arrow 2. Exemplarily, the brightness value F2 at the current level of brightness adjustment is the same as the maximum brightness value of the screen at the current level of brightness adjustment, both of which are 491.5 nit.

[0127] When the screen adjusts the current brightness level, its maximum brightness value becomes 491.5nit accordingly. At this time, when the input grayscale value is 1023, the corresponding brightness value is 491.5nit. However, the Gamma curve corresponding to the level with a maximum brightness value of 491.5nit does not actually exist. Therefore, it is necessary to use the Gamma curve corresponding to the specified level of brightness adjustment, that is, the maximum brightness value of 500nit. Figure 2When the solid line in the figure obtains the brightness value displayed as 491.5nit, what should the corresponding input grayscale value actually be, and replaces the initial input grayscale value of the source image on the screen with the actual input grayscale value, so as to display the normal brightness of the pixel point at the current level of the brightness adjustment of the screen. Specifically, when obtaining the input grayscale value corresponding to the brightness value F2 at the current level of the brightness adjustment of the pixel point, it is necessary to use the corresponding point of the brightness value F2 at the current level of the new brightness adjustment on the Gamma correction curve at the original specified level of the screen brightness adjustment, that is, point a in the figure, as shown by arrow 3.

[0128] At this time, the ordinate of point a is the brightness value F2 at the current level of brightness adjustment. For example, the maximum brightness value of the screen at the current level of brightness adjustment is 491.5 nit, and the abscissa of point a is the grayscale value f corresponding to the brightness value of the pixel at the current level of brightness adjustment after the screen reference brightness is adjusted. Therefore, the abscissa of point a can be obtained by the position of point a on the Gamma correction curve, for example, 1015, that is, the grayscale value f corresponding to the brightness value of the pixel at the current level of brightness adjustment, as shown by arrow 4. In this way, 1015 can be used as the actual input grayscale value of a certain pixel when it displays 491.5 nit. Correspondingly, at the level of brightness adjustment with the maximum brightness value of the screen being 491.5, the actual first input grayscale values ​​corresponding to the first brightness values ​​of other pixels on the screen at the current level of brightness adjustment can also be determined by the same method.

[0129] It should be noted that the grayscale value of each pixel on the screen usually has a range, that is, it will be less than or equal to a maximum grayscale value, so that the points on the curve will be located to the left of the vertical line whose horizontal axis is the maximum grayscale value max. Usually, the maximum grayscale value is usually the grayscale value input when the screen displays a full white picture.

[0130] In this embodiment, when adjusting the brightness of the screen, the correspondence between the input grayscale value of the screen and the displayed brightness value is always in accordance with the gamma curve, so as to avoid grayscale color deviation of the brightness displayed on the screen during the adjustment process. At the same time, the method only needs a set of discrete values ​​to represent the correspondence between the input grayscale value and the displayed brightness value, and based on this set of discrete values, the actual input grayscale value that the screen should have in order to display the proper brightness after the gear of the brightness adjustment is changed is determined, which saves storage space and reduces hardware costs; and because the set of discrete values ​​includes the correspondence between all integer grayscale values ​​and the corresponding displayed brightness values, the input grayscale value determined is more accurate, and the accuracy of the screen brightness adjustment is also higher.

[0131] In order to further reduce the occupied storage space and reduce the hardware cost, the preset Gamma correction lookup table usually stores a limited number of discrete values. For example, only 30 typical input grayscale values ​​and displayed brightness values ​​can be measured. At this time, the preset corresponding relationship is 30 groups of discrete points. The 30 groups of discrete points are all located on the same Gamma curve. Optionally, the preset corresponding relationship can be called a Gamma correction lookup table. Optionally, the 30 groups of discrete points can be evenly spaced on the Gamma curve. In this way, although multiple grayscale values ​​and corresponding display brightness values ​​are stored in the Gamma correction lookup table, the number of grayscale values ​​is less than the total number of grayscale values ​​that can be displayed on the screen. In this way, when the brightness adjustment gear of the screen is adjusted from the specified gear of the brightness adjustment to the current gear of the brightness adjustment, the brightness value displayed by each pixel on the screen at the current gear of the brightness adjustment may not be stored in the preset Gamma correction table. Therefore, when executing step S102 in the screen brightness control method of Example 1, that is, when determining the input grayscale value corresponding to the brightness value at the current level of brightness adjustment based on the preset Gamma correction lookup table, the linear interpolation method can also be used to obtain and calculate the grayscale value. Figure 3 1 is a flow chart of determining a first input grayscale value corresponding to a first brightness value at a current brightness adjustment level provided by an embodiment of the present application. Figure 3 As shown, in this embodiment, as another optional implementation, the step of determining the input grayscale value corresponding to the brightness value at the current gear of the brightness adjustment based on the preset Gamma correction lookup table may specifically include the following steps:

[0132] S201. Determine two display brightness values ​​directly adjacent to a first brightness value at a current brightness adjustment level based on a gamma correction lookup table.

[0133] In order to save hardware resources, only a part of all the Gamma correction relationships between the output brightness value and the input grayscale value is included in the preset Gamma correction lookup table. Therefore, if the screen is adjusted from the specified level of brightness adjustment to the current level of brightness adjustment, and the first brightness value of the pixel corresponding to the current level of brightness adjustment is not included in the part of the Gamma correction relationship, a grayscale value approximate to the first input grayscale value corresponding to the first brightness value at the current level of brightness adjustment can be obtained by linear interpolation method, and the approximate grayscale value is used as the actual input grayscale value of the screen, so that the screen can achieve normal brightness display at the current level of brightness adjustment.

[0134] Since the correspondence between each brightness value and grayscale value in the gamma correction lookup table is located on a gamma curve, when the arc length in the gamma curve is small, it can be approximated by a straight line, and the brightness value and grayscale value that satisfy the equation of the straight line can also be approximately equivalent to being located on the gamma curve.

[0135] Exemplarily, several groups of known correspondences between appropriate brightness values ​​and grayscale values ​​can be selected in the Gamma correction lookup table. For example, two groups of correspondences between output brightness values ​​and input grayscale values ​​can be selected, and linear interpolation calculations can be performed based on these correspondences. Specifically, two display brightness values ​​directly adjacent to the first brightness value at the current gear of the brightness adjustment can be selected. Since these two display brightness values ​​are directly adjacent to the first brightness value at the current gear of the brightness adjustment, the first brightness value at the current gear of the brightness adjustment is located between the two display brightness values, and the two display brightness values ​​are brightness values ​​adjacent to the first brightness value at the current gear of the brightness adjustment in the Gamma correction lookup table.

[0136] S202: Establish a linear interpolation equation based on two directly adjacent display brightness values ​​and their corresponding grayscale values.

[0137] After obtaining two display brightness values ​​directly adjacent to the first brightness value at the current gear of the brightness adjustment, a linear interpolation equation that approximately satisfies the corresponding arc segment in the Gamma curve can be established based on the two display brightness values ​​and the corresponding grayscale values, such as a straight line equation. In an optional case, the straight line equation is a univariate equation, and the number of variables and dependent variables is only one. By taking appropriate brightness values ​​and grayscale values, the straight line equation can also approximately satisfy the relationship between the first brightness value at the current gear of the brightness adjustment and the corresponding first input grayscale value, and can be used as a linear interpolation equation. For example, when the screen is adjusted from a specified gear to the current gear of the brightness adjustment, a linear interpolation equation can be established based on the two directly adjacent display brightness values ​​and the corresponding grayscale values.

[0138] Specifically, one of the brightness value and the grayscale value can be used as a variable of the equation, and the other as a dependent variable of the equation, so that multiple corresponding relationships including the maximum brightness value of the screen at the specified level of brightness adjustment and the corresponding grayscale value are substituted into the linear interpolation equation, thereby inverting the specific expression of the linear interpolation equation. Exemplarily, assuming that the maximum brightness value of the screen at the specified level is one of two directly adjacent display brightness values, the maximum brightness value of the screen at the specified level and the corresponding grayscale value can be used as the first group of variables and dependent variables, and the brightness value and the corresponding grayscale value adjacent to the first brightness value at the current level of brightness adjustment and less than the first brightness value are selected in the preset Gamma correction lookup table as the second group of variables and dependent variables; they are used as known parameters of the equation, and the original parameters in the equation are used as the quantities to be obtained. The specific values ​​of the original known parameters of the equation can be inverted through multiple groups of variables and dependent variables; after substituting the specific values ​​of the parameters into the equation, the linear interpolation equation can be obtained. The following is an example of the process of obtaining the linear interpolation equation.

[0139] As one optional implementation, when a linear interpolation equation is established based on two directly adjacent display brightness values ​​and their corresponding grayscale values, the two display brightness values ​​directly adjacent to the first brightness value at the current gear of the brightness adjustment are the maximum brightness value at the specified gear and another adjacent brightness value. Figure 4 Schematic diagram of the Gamma curve corresponding to the Gamma correction lookup table in the screen brightness control method provided in the embodiment of the present application. Figure 4 As shown, since the brightness value and grayscale value in the preset Gamma correction lookup table are located on the same Gamma curve with the input grayscale value as the horizontal axis coordinate and the displayed brightness value as the vertical axis coordinate, the maximum brightness value and the corresponding grayscale value of the screen at the specified level of brightness adjustment are the vertical coordinate and horizontal coordinate of point A on the Gamma curve, respectively, and the brightness value of each pixel point on the screen at the specified level and the grayscale value corresponding to the brightness value are the vertical coordinate and horizontal coordinate of point B on the Gamma curve, respectively. At this time, a point C can be selected on the Gamma curve, the vertical coordinate of point C is the other adjacent brightness value of the two directly adjacent display brightness values, and the horizontal coordinate is the grayscale value corresponding to the other adjacent brightness value.

[0140] Since the first brightness value of the screen pixel under the current brightness adjustment level is between two directly adjacent display brightness values, point B will also be between point A and point C. In this way, if a straight line is drawn through point A and point C, point B will also be approximately on the straight line, so the equation of the straight line can be obtained based on the coordinates of point A and point C, and the equation can be used as a linear interpolation equation to obtain the coordinates of point B.

[0141] Specifically, a and b can be determined according to the formulas Y1=a*X1+b and Y2=a*x2+b.

[0142] Among them, Y1 is the maximum brightness value of the screen under the specified brightness adjustment level, X1 is the grayscale value corresponding to the maximum brightness value of the screen under the specified brightness adjustment level, Y2 is the brightness value of point C, and X2 is the grayscale value corresponding to point C.

[0143] Since the linear interpolation equation is an equation expression of a straight line, the linear interpolation equation can be set to y=a*x+b; where x is the horizontal coordinate, that is, the grayscale value; y is the vertical coordinate, that is, the brightness value corresponding to the grayscale value, and a is the slope of the straight line represented by the linear interpolation equation, and b is the intercept of the straight line represented by the linear interpolation equation on the y-axis. Since the straight line represented by the linear interpolation equation passes through point A and point C, the horizontal and vertical coordinates of point A and point C can be substituted into the linear interpolation equation to find the values ​​of a and b.

[0144] After obtaining the specific values ​​of a and b in the previous step, a can be made to represent the slope of the line represented by the linear interpolation equation, and b can be made to represent the intercept of the line represented by the linear interpolation equation on the vertical axis, thereby establishing a linear interpolation equation based on the actual values ​​of a and b. The line represented by the linear interpolation equation can approximate the arc segment of the Gamma curve between point A and point C.

[0145] S203: Acquire a first input grayscale value corresponding to the first brightness value according to a linear interpolation equation and a first brightness value at a current gear of brightness adjustment.

[0146] After the linear interpolation equation is obtained based on the correspondence between two directly adjacent brightness values ​​and grayscale values, the first brightness value of any pixel point at the current level of brightness adjustment can be substituted into the linear interpolation equation as a variable, and the dependent variable of the obtained equation can be approximately equal to the first input grayscale value corresponding to the first brightness value of the pixel point at the current level of display brightness adjustment, as shown in step S303.

[0147] Specifically, in this step, the formula y=a*x+b can be used.

[0148] Get the input grayscale value corresponding to any pixel point, where y is the first brightness value at the current gear of brightness adjustment, and x is the first input grayscale value corresponding to the first brightness value at the current gear of brightness adjustment. In this way, the points with the first brightness value at the current gear of brightness adjustment as the vertical coordinate and the first input grayscale value corresponding to the first brightness value at the current gear of brightness adjustment as the horizontal coordinate are all located on a straight line with a as the slope and b as the intercept on the y-axis. Among them, the specific values ​​of a and b have been calculated, so the grayscale value corresponding to any pixel point in each pixel point can be directly calculated according to the formula. Perform the above processing on each pixel point on the screen to obtain the first input grayscale value that should be input for each pixel point when the gear of the screen is the current gear of brightness adjustment. In addition, a linear interpolation formula can also be established based on other linear interpolation algorithms, and the specific expression of the linear interpolation formula can be determined based on the relationship between the input grayscale value and the displayed brightness value in the preset gamma correction lookup table, and the linear interpolation formula can be used to obtain the first input grayscale value corresponding to the first brightness value at the current level of brightness adjustment, as the first input grayscale value corresponding to any pixel in each pixel when the display displays the first brightness value at the current level of brightness adjustment.

[0149] In this embodiment, when the brightness of the screen is adjusted, the input grayscale value of the screen and the displayed brightness value are always in line with the gamma curve, so that grayscale color deviation and brightness flickering of the screen display are avoided during the adjustment process; at the same time, the method only needs to specify the gamma correction relationship under the gear, and can determine the gamma correction of the screen display brightness at other gears of the brightness adjustment, and there is no need to store the gamma correction relationship under other gears, which saves storage space and reduces hardware costs; and the preset gamma correction lookup table used only includes a limited number of corresponding relationships between input grayscale values ​​and displayed brightness values, and the other corresponding relationships included in the preset gamma correction lookup table are obtained by simple linear interpolation operations. While achieving higher grayscale value input accuracy, the operation speed is faster and the processor overhead is smaller.

[0150] When the screen is an AMOLED screen, the luminous characteristics of individual pixels will change due to process reasons (such as uniformity of evaporation of the entire surface and film thickness control) during the production process of the AMOLED display panel. At this time, when the driving voltage of individual pixels is the same, the current flowing through them will be different, which will cause individual pixels on the screen to have uneven brightness (Mura) when displayed. In order to correct the Mura phenomenon of the screen, the screen also needs to compensate and eliminate the Mura phenomenon, that is, the Demura step. Therefore, on the basis of the aforementioned embodiment, a step for eliminating the Mura phenomenon can also be added to the method for controlling the screen brightness. Figure 5FIG. 1 is a flow chart of another method for controlling screen brightness provided by an embodiment of the present application. Figure 5 As shown, when the screen includes a non-uniform Mura area, and the brightness values ​​corresponding to the pixels of the screen at the initial brightness adjustment level are all the second brightness values, in the screen brightness control method provided in this embodiment, in order to correct and compensate for the screen Mura phenomenon while controlling the brightness of the screen, before determining the brightness value corresponding to the screen at the current level of the brightness adjustment, the following steps may also be included:

[0151] S301 : Before demodulating the screen, determine a second input grayscale value corresponding to a second brightness value based on a preset gamma correction lookup table.

[0152] Specifically, when the screen is displaying, due to the sensitivity of the human eye or the photoelectric characteristics of the screen itself, there will be distortion between the image output by the screen and the input image. Therefore, in order to avoid the deviation between the brightness value displayed on the screen and the brightness value of the original image, it is necessary to correct the grayscale value input to the screen. Specifically, when performing gamma correction, the pixels of the screen can be gamma compensated using a preset Gamma correction lookup table to obtain the input grayscale value corresponding to each pixel when the brightness value displayed by each pixel is the second brightness value at the specified level of the screen, thereby correcting the deviation in brightness of the image actually displayed on the screen. The specific method and steps for obtaining the input grayscale value can be seen in the specific description of step S102 in the aforementioned embodiment, which will not be repeated here.

[0153] When the second brightness values ​​displayed by each pixel of the screen at the initial brightness adjustment level are all the same value, for example, the maximum brightness value of the screen at the initial brightness adjustment level, the screen displays a uniform color image. In this way, the second input grayscale value corresponding to the maximum brightness value displayed by the pixel when the screen is at the initial brightness adjustment level can be determined based on the preset Gamma correction lookup table.

[0154] S302: Control the display brightness value of each pixel of the screen according to the second input grayscale value.

[0155] After obtaining the second input grayscale value, the input grayscale value of each pixel point can be determined as the second input grayscale value, so that the pixel point of the screen should display the second brightness value corresponding to the second input grayscale value. Therefore, the display brightness of each pixel point can be controlled according to the second input grayscale value to make the screen display.

[0156] At this time, the screen includes a Mura area, that is, each pixel includes pixels with uneven brightness values, so Demura adjustment is required to ensure that all pixels maintain uniform brightness when displaying the image.

[0157] Specifically, since there may be a Mura phenomenon in the screen, when the same grayscale value is input to each pixel on the screen, some areas or some pixels may show a different brightness output from other pixels. Therefore, a Demura step is required so that the same grayscale value input to each pixel on the screen can correspond to the same brightness value. Since mura compensation is based on the brightness data after gamma correction, the compensation step needs to perform gamma correction on the initial pixel of the screen according to the preset Gamma correction lookup table, so that the output brightness value of the screen follows the gamma curve with the input grayscale value.

[0158] There are many types of compensation methods, such as internal compensation or external compensation. When performing compensation, usually the actual brightness value corresponding to the input of the pixel when the specified grayscale value is input, exemplarily, the second input grayscale value, or the grayscale value corresponding to the input of the pixel when the pixel outputs a certain brightness value, exemplarily, the maximum brightness value of the screen under the initial brightness adjustment gear, is obtained, and compensation is performed according to the relationship between the grayscale value and the brightness value of the pixel, so that the input and output characteristics of each pixel on the screen remain consistent.

[0159] Specifically, when performing compensation, it is usually possible to input the same second input grayscale value to each pixel on the screen. At this time, if there is no mura area on the screen, the brightness output by the screen should be equal everywhere and be the second brightness value. Therefore, the screen can be photographed using a high-power camera or other equipment to obtain the actual display brightness of each pixel on the screen. If there is a Mura phenomenon on the screen, the brightness of the pixels in the area where the Mura phenomenon occurs will be different from the brightness of the pixels outside the area. In this way, after analyzing the data captured by the camera, the compensation data, such as a Mura compensation table, can be used to compensate for the brightness of each pixel, so that the entire screen can display uniform brightness. Specifically, the compensation data may include the coordinates of the pixels to be compensated on the screen and the correspondence between the grayscale values ​​before and after compensation when the pixels display uniform brightness.

[0160] In order to facilitate the subsequent brightness control, in step S301, the brightness value of each pixel in the screen can be set to the maximum brightness value corresponding to the screen at the initial brightness adjustment level, that is, the brightness of the screen when it displays full white color at the brightness adjustment level. For example, when the entire screen outputs the maximum brightness value, the Mura compensation data can be used to change or replace the input grayscale value of the pixel in the mura area, so that the pixel in the mura area can output the same display brightness value as the pixel in other areas.

[0161] In this way, after the Demura step, the Mura phenomenon of the screen can be compensated so that each pixel of the screen has uniform brightness.

[0162] S303: Determine a first brightness value corresponding to the current brightness adjustment level of the screen.

[0163] Since the screen can display uniformly after the Demura step, the first brightness value corresponding to each pixel for normal display under the current brightness adjustment level can be determined according to the current brightness adjustment level.

[0164] S304. Determine a first input grayscale value corresponding to the first brightness value based on a preset gamma correction lookup table, where the gamma correction lookup table is a gamma correction relationship between the brightness value of the screen and the initial input grayscale value of the screen at a specified level of brightness adjustment.

[0165] When the screen performs brightness control, for example, when the screen brightness adjustment level is adjusted from the original specified level to the current level, the brightness of each pixel on the screen also needs to change accordingly to ensure the correct display of the image. In order to determine the display output of the screen for the image at this time, it is necessary to re-determine the first input grayscale value that each pixel should have when the first brightness value of each pixel on the screen is displayed at the current level of brightness adjustment based on the gamma curve characteristics between the screen input and output.

[0166] Specifically, since the relationship between the input grayscale value and the output brightness value of the screen can be obtained through a preset Gamma correction lookup table, when the screen is at the current brightness adjustment level, the preset Gamma correction lookup table can also be used to obtain the first input grayscale value that each pixel on the screen needs to actually input in order to maintain the corresponding first brightness value at the current brightness adjustment level. When using the preset Gamma correction lookup table to obtain the actual input grayscale value of each pixel on the screen, it can be obtained by formula calculation. The specific steps can be found in the relevant descriptions of each step in the aforementioned embodiment, which will not be repeated here.

[0167] S305: Control the display brightness value of the screen according to the first input grayscale value.

[0168] After obtaining the actual first input grayscale value that each pixel should have in order to display the corresponding brightness in order for the screen to display the image normally after the brightness changes, the first input grayscale value can be used as the actual input of the pixel, and the preset Gamma correction lookup table can be used to achieve the correct display brightness output, so that when the screen is adjusted to the current brightness adjustment level, the image can be displayed correctly.

[0169] In this embodiment, it is first necessary to make each initial pixel point on the screen output the same second grayscale value, and then use mura compensation to make the brightness of each pixel point on the screen consistent. Finally, when the screen brightness is adjusted, the correct correspondence between the input grayscale value and the output brightness value of the pixel point after the screen brightness changes is obtained, so that the brightness of the image displayed on the screen is consistent with the brightness of the image to be displayed. In this way, the brightness of the screen is corrected based on the same preset Gamma correction lookup table before and after the mura compensation step, so that the screen brightness can be controlled while maintaining the uniformity of the screen display by using the mura compensation step. At the same time, there is a correct correspondence between the input grayscale value and the output brightness value of the screen, so that the screen image displays normal brightness and light and dark changes. Compared with the existing screen brightness control method in which the mura compensation step and the gamma correction step are performed separately, and the mura compensation step is performed by the optical manufacturer, and the gamma correction step is mainly completed by the driver chip manufacturer, it only needs to use the same preset gamma correction lookup table to operate, so it can be integrated into a same hardware architecture, and the integration is better.

[0170] In this embodiment, before demura is performed on the screen, gamma correction is performed on the screen containing the mura area, and gamma correction is performed on the screen after the demura operation during the brightness adjustment process, which can not only ensure the uniformity of the screen, but also enable the screen to always achieve correct brightness display during the brightness adjustment process. In addition, the gamma correction before demura is performed based on the same gamma correction lookup table in the brightness adjustment process, which can achieve better hardware integration, save storage space, reduce hardware costs, and have better hardware integration.

[0171] The present application also provides a device for controlling screen brightness to execute the method for controlling screen brightness in the above-mentioned embodiment. Figure 6 As shown, the screen brightness control device 100 provided in this embodiment may include:

[0172] The brightness determination module 61 is used to determine a first brightness value corresponding to a current brightness adjustment level of the screen.

[0173] The first Gamma correction module 62 is used to determine a first input grayscale value corresponding to a first brightness value based on a preset Gamma correction lookup table, wherein the Gamma correction lookup table is a Gamma correction relationship between the brightness value of the screen and the initial input grayscale value of the screen at a specified brightness adjustment level.

[0174] The brightness adjustment module 63 is used to control the display brightness value of the screen according to the first input grayscale value. For the specific functions of the brightness determination module 61, the first Gamma correction module 62 and the brightness adjustment module 63, please refer to the description of steps S101 to S103 on the method side.

[0175] Optionally, the gamma correction lookup table may include multiple discrete grayscale values ​​and multiple display brightness values, the number of grayscale values ​​is equal to the number of display brightness values, the grayscale values ​​correspond one-to-one to the display brightness values, and the number of discrete grayscale values ​​is equal to the total number of grayscale values ​​of the screen.

[0176] Alternatively, the gamma correction lookup table may also include multiple discrete grayscale values ​​and multiple display brightness values, the number of grayscale values ​​is equal to the number of display brightness values, the grayscale values ​​correspond one-to-one to the display brightness values, and the number of discrete grayscale values ​​is less than the total number of grayscale values ​​of the screen.

[0177] Optionally, two-dimensional coordinate points formed by discrete grayscale values ​​and display brightness values ​​corresponding to any of the discrete grayscale values ​​are all located on a Gamma curve, wherein the abscissa of the Gamma curve represents the grayscale value, and the ordinate of the Gamma curve represents the display brightness value.

[0178] Optionally, the current brightness value of the screen at the current gear and the previous brightness value of the previous gear of the brightness adjustment meet a preset condition, wherein the current brightness value and the previous brightness value correspond to the same input grayscale value, and the preset condition is: the ratio of the brightness value difference of adjacent gears to the previous brightness value satisfies Weber's law. The brightness value difference is the difference between the current brightness value and the previous brightness value.

[0179] Optionally, the maximum brightness value supported by the screen at the specified level is greater than the maximum brightness value supported by the screen at the current level of brightness adjustment.

[0180] Optionally, specify the maximum level supported when adjusting screen brightness.

[0181] Optionally, the first Gamma module 62 is specifically used to first determine the initial input grayscale value of the screen when the brightness value displayed on the screen is the first brightness value corresponding to the current brightness adjustment level; and then replace the initial input grayscale value with the input grayscale value determined based on the Gamma correction lookup table as the first input grayscale value corresponding to the first brightness value.

[0182] Optionally, the correspondence between multiple grayscale values ​​and multiple display brightness values ​​in the Gamma correction lookup table conforms to the Gamma correction formula, wherein the display brightness value is the input of the Gamma correction formula and the grayscale value is the output of the Gamma correction formula; in this case, the control device may further include: a Gamma correction lookup table acquisition module 66, which is used to calculate multiple grayscale values ​​corresponding to the multiple display brightness values ​​based on the multiple display brightness values ​​and the correction formula.

[0183] Optionally, when the first brightness value at the current gear of the brightness adjustment is not included in the Gamma correction lookup table, the first Gamma correction module 62 is also used to first obtain the display brightness value in the Gamma correction lookup table that is closest to the first brightness value at the current gear of the brightness adjustment; and then use the grayscale value corresponding to the display brightness value that is closest to the first brightness value at the current gear of the brightness adjustment as the first input grayscale value corresponding to the first brightness value.

[0184] Optionally, when the first brightness value at the current gear of the brightness adjustment is not included in the Gamma correction lookup table, the first Gamma correction module 62 is specifically used to first determine two display brightness values ​​directly adjacent to the first brightness value at the current gear of the brightness adjustment based on the Gamma correction lookup table; then establish a linear interpolation equation based on the two directly adjacent display brightness values ​​and their corresponding grayscale values; finally, obtain a first input grayscale value corresponding to the first brightness value according to the linear interpolation equation and the first brightness value at the current gear of the brightness adjustment.

[0185] Optionally, in order to eliminate the uneven brightness (Mura) phenomenon of individual pixels on the screen during display and ensure the uniformity of the screen display, at this time, the initial preset brightness value of each pixel on the screen is the second brightness value, and the acquisition module 62 is also used to determine the second input grayscale value corresponding to the second brightness value when the corresponding brightness value is the second brightness value under the initial brightness adjustment gear based on the preset gamma correction lookup table; then the second input grayscale value is used as the grayscale value input for each pixel of the screen.

[0186] At this time, in order to ensure the uniformity of screen display, Figure 7 Another screen brightness control device 200 is provided, and Figure 7 Similar to the screen brightness control device 100 in the embodiment, the screen brightness control device 200 also includes the above modules, and the screen brightness control device 200 may further include:

[0187] The second Gamma correction module 64 is used to determine a second input grayscale value corresponding to a second brightness value based on a preset Gamma correction lookup table before demura is performed on the screen.

[0188] The second Gamma correction module 64 is further configured to use the second input grayscale value as the input grayscale value of each pixel point on the screen.

[0189] In addition, the device further includes a Mura correction module 65 for demodulating the screen. The specific functions of the second Gamma correction module 64 and the Mura correction module 65 can be seen in the description of steps S301 to S302 of the aforementioned method.

[0190] It should be understood that Figure 6 to Figure 7 The division of the modules of the device shown is only a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or they can be physically separated. And these modules can all be implemented in the form of software calling through processing elements; they can also be all implemented in the form of hardware; some modules can also be implemented in the form of software calling through processing elements, and some modules can be implemented in the form of hardware. For example, the first Gamma correction module 62 can be a separately established processing element, or it can be integrated in a certain chip of the device for implementation. In addition, it can also be stored in the memory of the device in the form of a program, and a certain processing element of the device calls and executes the function of the first Gamma correction module 62. The implementation of other modules is similar. In addition, these modules can be fully or partially integrated together, or they can be implemented independently. The processing element described here can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each unit above can be completed by an integrated logic circuit of hardware in the processor element or instructions in the form of software.

[0191] The above modules may be one or more integrated circuits configured to implement the above methods, such as one or more application-specific integrated circuits (ASICs), or one or more digital signal processors (DSPs), or one or more field-programmable gate arrays (FPGAs). For another example, when a module above is implemented in the form of a processing element scheduler, the processing element may be a general-purpose processor, such as a central processing unit (CPU) or other processor that can call a program. For another example, these modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0192] Figure 8 Schematic diagram of the hardware structure of a terminal device provided in an embodiment of the present application. Figure 8 As shown, the terminal device 300 includes: a processor 71, a first Gamma selector 72, a first Gamma correction controller 73 and a screen 74.

[0193] The processor 71 is used to determine a first brightness value corresponding to the current brightness adjustment level of the screen 74 .

[0194] The first Gamma selector 72 is used to determine a first input grayscale value corresponding to a first brightness value based on a preset Gamma correction lookup table, wherein the Gamma correction lookup table is a Gamma correction relationship between the brightness value of the screen and the initial input grayscale value of the screen at a specified brightness adjustment level.

[0195] The first Gamma correction controller 73 is used to control the display brightness value of the screen according to the first input grayscale value.

[0196] In this way, the terminal device in this embodiment can execute the screen brightness control method in the aforementioned embodiment. The specific process and steps of the screen brightness control method have been described in detail in the aforementioned embodiment and will not be repeated here.

[0197] In this way, after the processor 71 determines the first brightness value, the first Gamma selector 72 can be used to determine the first input grayscale value corresponding to the first brightness value according to the preset Gamma correction lookup table, and then the first Gamma correction controller 73 controls the display brightness value of the screen 74 according to the first input grayscale value. Among them, the specific functions and effects performed by the first Gamma selector 72 are similar to the functions of the first Gamma correction module 62 in the aforementioned embodiment, and the specific functions and effects performed by the first Gamma correction controller 73 are similar to the functions of the brightness adjustment module 63 in the aforementioned embodiment, which will not be repeated here.

[0198] The first Gamma selector 72 may be integrated on the processor 71, or may be a hardware logic or hardware circuit independent of the processor 71. The first Gamma correction controller 73 may generally be hardware independent of the processor 71, such as a driving circuit.

[0199] In addition, optionally, the terminal device 300 may further include a memory 75, and the memory 75 is used to store a preset gamma correction lookup table.

[0200] The screen 74 is usually composed of an organic light emitting display (OLED) or an active-matrix organic light emitting diode (AMOLED). For example, the screen 74 is an OLED screen. In order to allow each pixel of the OLED screen to display the desired brightness and color output, the first Gamma correction controller in the terminal device can generate a corresponding voltage for driving according to the input grayscale value obtained by the first Gamma selector. When different voltages are applied to the screen, different brightness can be displayed, thereby displaying a display brightness value corresponding to the input grayscale value.

[0201] Specifically, the first Gamma correction controller 73 may include a voltage generator and a brightness controller, wherein the voltage generator can be used to generate a corresponding reference voltage according to an input grayscale value, and the brightness controller can be used to control the screen to display a display brightness value corresponding to the input grayscale value based on the reference voltage.

[0202] Among them, since the input grayscale value is usually a digital signal, in order to convert the input grayscale value into an analog voltage value, the voltage generator 731 can be optionally a digital to analog converter (DAC). The digital to analog converter is used to convert the input grayscale value into an analog reference voltage value, so that the brightness controller 732 can control the display brightness value of the screen according to the reference voltage, so that the screen displays the corresponding display brightness value when powered on. Specifically, the digital to analog converter can convert the input grayscale value into an actual reference voltage value after receiving the input grayscale value in the form of a digital signal. When the input grayscale value is different, the corresponding reference voltage value will also change accordingly, so that the screen can emit light of different brightness under the stimulation of different reference voltage values ​​and current values ​​to display the actual image.

[0203] The processor 71, the first Gamma selector 72, the first Gamma correction controller 73 and the memory 75 can use a communication bus or other data paths to achieve data and signal transmission. Since the memory 75 and the processor 71, the first Gamma selector 72 and the first Gamma correction controller 73 are electrically connected, the preset gamma correction lookup table stored in the memory 75 can be transmitted to the first Gamma selector 72, so that the first Gamma selector 72 can search the preset gamma correction lookup table for the input grayscale value that the pixel point should have after the gear of the brightness adjustment of the screen 74 is changed, and the first Gamma correction controller 73 can control the display brightness value of each pixel point of the screen 74 according to the input grayscale value.

[0204] The processor 71 is usually the control center of the terminal device, and can be connected to different hardware parts such as the memory 75 by a communication bus, and execute various functions of the terminal device and process data by running or executing software programs and / or modules, and calling data stored in the memory, so as to complete the brightness control operation of the screen. The processor 71 can be a microcontroller unit (MCU), a central processing unit (CPU), or an independent system-on-a-chip (SOC), or one or more integrated circuits configured to implement the above method, such as: one or more application specific integrated circuits (ASIC), or one or more microprocessors (digital singnal processors, DSP), or one or more field programmable gate arrays (FPGA), etc.

[0205] Optionally, the processor 71 may include one or more processing units; and different processing units may be used to respectively execute the above-mentioned different instructions and programs to respectively perform different functions.

[0206] The memory 75 may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 74 may exist independently and be connected to the processor 71 and the first gamma selector 72 through a bus. The memory 75 may also be integrated with the processor 71.

[0207] In addition to storing the preset gamma correction lookup table, optionally, the memory 75 can also be used to store application code for executing the solution of the present application, and the execution is controlled by the processor 71. The processor 71 is used to execute the application code stored in the memory 75, thereby realizing the screen brightness control method provided in the above embodiment of the present application.

[0208] In addition, due to the process of the OLED screen or AMOLED screen itself, the light-emitting characteristics of individual pixels often change, resulting in uneven brightness (Mura) of individual pixels on the screen when displayed. In order to eliminate the uneven brightness (Mura) phenomenon of the OLED screen, the terminal device can optionally be used to perform a Demura step to compensate for pixels with uneven brightness values. Fig. 9 Another terminal device is provided, and Figure 8 Similar to the terminal device in, the terminal device 400 also includes the above-mentioned processor 71, the first Gamma selector 72, the first Gamma correction controller 73 and the screen 74. In addition, if the brightness values ​​corresponding to each pixel of the screen 74 at the initial gear of the brightness adjustment are all the second brightness values, the terminal device 400 may also include: a second Gamma selector 76 and a second Gamma correction controller 77. Among them, the second Gamma selector 76 is used to determine the second input grayscale value corresponding to the second brightness value based on a preset Gamma correction lookup table before demura is performed on the screen 74. The second Gamma correction controller 77 is used to control the display brightness value of each pixel of the screen according to the second input grayscale value. Specifically, the functions and effects of the second Gamma selector 76 and the second Gamma correction controller 77 are the same as the functions of the second Gamma correction module in the aforementioned embodiment, and will not be repeated here.

[0209] The second Gamma selector 76 may be integrated on the processor 71, or may be hardware independent of the processor 71. The second Gamma correction controller 77 is usually hardware independent of the processor 71, such as a driving circuit.

[0210] Specifically, the terminal device 400 needs to cooperate with other external devices to obtain mura compensation data. The external device usually includes a sensing element for sensing the actual brightness of the screen 75. For example, it can be a high-power camera, etc. When the screen 75 is displayed under the drive of the test signal, the brightness value corresponding to each pixel of the screen 75 at the initial gear of the brightness adjustment is the second brightness value. At this time, the second Gamma selector 76 determines the second grayscale value corresponding to the second brightness value according to the preset Gamma correction lookup table, and the second Gamma correction controller 77 uses the second input grayscale value to control the display brightness value of each pixel. At this time, the sensing element will measure the actual brightness displayed by the screen 75, and then the terminal device 400 can obtain Mura compensation data according to the relationship between the actual brightness of the screen 75 and the input grayscale value, such as a Mura compensation table, and compensate the brightness of each pixel in the screen 75 according to the mura compensation table, so that the brightness of the entire screen 75 can be kept uniform. In this embodiment, for example, the brightness value of each pixel in the screen 75 can be kept at the second brightness value.

[0211] Exemplarily, the terminal device 400 may include a Mura correction controller 78 specifically used to obtain Mura compensation data and perform Mura compensation. The Mura correction controller 78 may be integrated with the processor 71, or may be a separate hardware or circuit.

[0212] In addition, the second Gamma correction controller 76 may also include a voltage generator and a brightness controller. The voltage generator can be used to generate a corresponding reference voltage according to the input grayscale value; and the brightness controller can be used to control the screen to display a display brightness value corresponding to the input grayscale value based on the reference voltage. The specific structure and function of the voltage generator and the brightness controller can be seen in the description of the above embodiment, and will not be repeated here.

[0213] In order to work with external devices such as high-power cameras, the terminal device may also include an I / O subsystem for connecting external devices and the terminal device itself. The I / O subsystem can be used to implement data interaction with external devices, thereby implementing the input and output of data collected by external devices, as well as controlling the working status of external devices.

[0214] In addition, the terminal device also includes a pulse width modulation (PWM) dimmer 79, which can modulate the on and off of internal switching devices such as transistor gates or MOS tube bases, thereby generating a series of pulses with equal pulse widths, and achieving different equivalent analog outputs by changing the width or duty cycle of the pulses, thereby adjusting the output brightness of the screen 75. Exemplarily, the PWM dimmer 79 is electrically connected to the screen 75, and the PWM dimmer 79 can receive digital signals from the control chip and convert the digital signals into pulses with different pulse widths or duty cycles, at which time, voltage signals with different amplitudes can be equivalently output. As the size of the voltage signal is different, each pixel on the screen 75 will also display different brightness, thereby achieving normal display of the image and brightness adjustment. Exemplarily, the PWM dimmer 79 can be electrically connected to the processor 71 or be a part of the Gamma correction controller to adjust the display brightness of the screen 75 according to data such as the input grayscale value.

[0215] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using a software program, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or may include one or more servers, data centers and other data storage devices that can be integrated with the medium. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a DVD), or a semiconductor medium (eg, a solid state disk (SSD)).

Claims

1. A method for controlling screen brightness, characterized in that: include: Determine a first brightness value corresponding to the current brightness adjustment level of the screen; Determine a first input grayscale value corresponding to the first brightness value based on a preset gamma correction lookup table, wherein the gamma correction lookup table is a gamma correction relationship between the brightness value of the screen and the initial input grayscale value of the screen at a specified brightness adjustment level; The display brightness value of the screen is controlled according to the first input grayscale value.

2. The control method according to claim 1, characterized in that: The screen includes a non-uniform Mura area, and if the brightness values ​​corresponding to each pixel of the screen at the initial level of brightness adjustment are all second brightness values, before determining the first brightness value corresponding to the screen at the current level of brightness adjustment, the method further includes: Before demura is performed on the screen, determining a second input grayscale value corresponding to the second brightness value based on the preset gamma correction lookup table; The display brightness value of each pixel point of the screen is controlled according to the second input grayscale value.

3. The control method according to claim 1, characterized in that: The gamma correction lookup table includes any one of the following: A plurality of discrete grayscale values ​​and a plurality of display brightness values, the number of the grayscale values ​​being equal to the number of the display brightness values, the grayscale values ​​corresponding to the display brightness values ​​one by one, and the number of the discrete grayscale values ​​being equal to the total number of grayscale values ​​of the screen; or, A plurality of discrete grayscale values ​​and a plurality of display brightness values, the number of the grayscale values ​​is equal to the number of the display brightness values, the grayscale values ​​correspond one to one with the display brightness values, and the number of the discrete grayscale values ​​is less than the total number of grayscale values ​​of the screen.

4. The control method according to claim 3, characterized in that: The two-dimensional coordinate points formed by the discrete grayscale values ​​and the display brightness values ​​corresponding to any of the discrete grayscale values ​​are all located on a Gamma curve, wherein the abscissa of the Gamma curve represents the grayscale value, and the ordinate of the Gamma curve represents the display brightness value.

5. The control method according to any one of claims 1 to 4, characterized in that: The maximum brightness value supported by the screen at the specified gear is greater than the maximum brightness value supported by the screen at the current gear.

6. The control method according to any one of claims 1 to 5, characterized in that: The specified gear is the maximum gear supported when adjusting the brightness.

7. The control method according to any one of claims 3 to 6, characterized in that: The correspondence between the multiple grayscale values ​​and the multiple display brightness values ​​in the Gamma correction lookup table conforms to a Gamma correction formula, wherein the display brightness value is an input of the Gamma correction formula, and the grayscale value is an output of the Gamma correction formula; The determining the first input grayscale value corresponding to the first brightness value based on a preset Gamma correction lookup table specifically includes: A plurality of first grayscale values ​​corresponding to the plurality of display brightness values ​​are calculated based on the plurality of display brightness values ​​and the correction formula.

8. The control method according to any one of claims 1 to 7, characterized in that: When the first brightness value at the current gear of the brightness adjustment is not included in the Gamma correction lookup table, determining the first input grayscale value corresponding to the first brightness value based on the preset Gamma correction lookup table includes: Obtain a display brightness value in the gamma correction lookup table that is closest to a first brightness value at a current level of the brightness adjustment; The grayscale value corresponding to the obtained display brightness value is used as the first input grayscale value corresponding to the first brightness value.

9. The control method according to any one of claims 1 to 8, characterized in that: When the first brightness value at the current gear of the brightness adjustment is not included in the Gamma correction lookup table, determining the first input grayscale value corresponding to the first brightness value based on the preset Gamma correction lookup table specifically includes: Determine two display brightness values ​​directly adjacent to the first brightness value at the current gear of the brightness adjustment based on the gamma correction lookup table; Establishing a linear interpolation equation based on the two directly adjacent display brightness values ​​and their corresponding grayscale values; A first input grayscale value corresponding to the first brightness value is acquired according to the linear interpolation equation and the first brightness value at the current gear of the brightness adjustment.

10. A screen brightness adjustment method, characterized in that: The method comprises: dividing each brightness adjustment level of the screen into a plurality of brightness adjustment points at equal intervals, each brightness adjustment point corresponding to an independent brightness value; When the screen is adjusted from a previous level before brightness adjustment to a current level after brightness adjustment, a current brightness value of the screen at the current level and a previous brightness value at the previous level satisfy a preset condition, wherein the current brightness value and the previous brightness value correspond to the same input grayscale value, and the preset condition is that a ratio of a brightness value difference corresponding to adjacent levels to the previous brightness value satisfies Weber's law, wherein the brightness value difference is the difference between the current brightness value and the previous brightness value.

11. The screen brightness adjustment method according to claim 10, characterized in that: The ratio of the brightness value difference corresponding to the adjacent gears to the previous brightness value is less than or equal to 0.

017.

12. The screen brightness adjustment method according to claim 10 or 11, characterized in that: The maximum brightness value of the screen at the current gear is 0.983 times the maximum brightness value at the previous gear.

13. The screen brightness adjustment method according to any one of claims 10 to 12, characterized in that: The different screens correspond to different brightness adjustment ranges; The absolute value relationship between the maximum brightness value corresponding to the screen at the specified brightness adjustment level and the maximum brightness value corresponding to the current level is converted into a relative value relationship, and the absolute value relationship between the first brightness value corresponding to the pixel point at the current level and the brightness value corresponding to the pixel point at the specified level is converted into a relative value relationship.

14. The screen brightness adjustment method according to claim 13, characterized in that: After the screen is adjusted from the designated gear to the current gear, the first brightness value corresponding to any pixel point at the current gear is normalized.

15. The screen brightness adjustment method according to claim 14, characterized in that: Normalizing the first brightness value corresponding to any pixel point at the current gear includes: Obtain the normalized brightness value according to the formula F2=F1*B2 / B1; Among them, F2 is the first brightness value corresponding to the current gear after the normalization processing, F1 is the brightness value corresponding to the specified gear after the normalization processing, B2 is the maximum brightness value of the screen at the current gear, and B1 is the maximum brightness value of the screen at the specified gear.

16. A terminal device, characterized in that: The terminal device comprises means for implementing at least one of the methods in claims 1-9.

17. A terminal device, characterized in that: The terminal device comprises means for implementing at least one of the methods in claims 10-15.

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