Calibrating input display data for seamless transitions between multiple display refresh rates - Patents.com

Abstract

The method may include measuring optical characteristics of the display panel for an input gray level at a first refresh rate. The method may also include measuring optical characteristics for a plurality of candidate gray levels at a second refresh rate. The method may further include selecting a gray level from the plurality of candidate gray levels that corresponds to the input gray level based on the measured optical characteristics of the display panel. The method may also include storing the gray level corresponding to the input gray level in the device, the device being configured to adjust the input display data using the gray level corresponding to the input gray level after the storing step when the display panel is transitioning from the first refresh rate to the second refresh rate.

Description

[Background technology]

[0001] background Refresh rate may refer to the number of times per second that an image on a device's display panel is refreshed. For example, a refresh rate of 60 Hertz (Hz) means that the image is refreshed 60 times per second. A higher refresh rate typically results in a better user experience, but also results in higher power consumption for the device.

[0002] Sometimes a display panel can operate at multiple refresh rates. For example, the refresh rate of a device's display panel may be set to 90 Hz when running a video streaming application and 60 Hz when running a word processing application. Summary of the Invention [Means for solving the problem]

[0003] overview The present disclosure generally relates to a display panel of a device. The display panel can be configured to operate at a first refresh rate or a second refresh rate. The device can be configured to adjust input display data when the display panel transitions from the first refresh rate to the second refresh rate according to optical characteristics of the display panel measured at the first refresh rate and the second refresh rate.

[0004] In a first aspect, a computer-implemented method is provided. The method may include measuring, from a device having a display panel configured to operate at multiple refresh rates, optical characteristics of the display panel for an input gray level at a first refresh rate. The method may further include measuring, from the device, optical characteristics of the display panel for a plurality of candidate gray levels at a second refresh rate. The method may also include selecting a gray level from the plurality of candidate gray levels corresponding to the input gray level based on the measured optical characteristics of the display panel for the input gray level and the plurality of candidate gray levels. The method may further include storing the gray level corresponding to the input gray level in the device, wherein, after the storing step, the device is configured to adjust input display data using the gray level corresponding to the input gray level when the display panel is transitioning from the first refresh rate to the second refresh rate.

[0005] In a second aspect, a system is provided. The system may include one or more processors. The system may also include data storage having stored therein computer-executable instructions that, when executed by the one or more processors, cause the system to perform operations. The operations may include measuring, from a device having a display panel configured to operate at multiple refresh rates, optical characteristics of the display panel for an input gray level at a first refresh rate. The operations may further include measuring, from the device, optical characteristics of the display panel for a plurality of candidate gray levels at a second refresh rate. The operations may also include selecting, from the plurality of candidate gray levels, a gray level corresponding to the input gray level based on the measured optical characteristics of the display panel for the input gray level and the plurality of candidate gray levels. The operations may further include storing, in the device, the gray level corresponding to the input gray level, wherein, after the storing step, the device is configured to adjust input display data using the gray level corresponding to the input gray level when the display panel is transitioning from the first refresh rate to the second refresh rate.

[0006] In a third aspect, a device is provided. The device includes one or more processors operable to perform operations. The operations may include measuring, from a device having a display panel configured to operate at multiple refresh rates, optical characteristics of the display panel for an input gray level at a first refresh rate. The operations may further include measuring, from the device, optical characteristics of the display panel for a plurality of candidate gray levels at a second refresh rate. The operations may also include selecting a gray level from the plurality of candidate gray levels corresponding to the input gray level based on the measured optical characteristics of the display panel for the input gray level and the plurality of candidate gray levels. The operations may further include storing the gray level corresponding to the input gray level in the device, and the device is configured, after the storing step, to adjust input display data using the gray level corresponding to the input gray level when the display panel is transitioning from the first refresh rate to the second refresh rate.

[0007] In a fourth aspect, an article of manufacture is provided. The article may include a non-transitory computer-readable medium having stored thereon program instructions that, when executed by one or more processors of the computing device, cause the computing device to perform operations. The operations may include measuring, from a device having a display panel configured to operate at multiple refresh rates, optical characteristics of the display panel for an input gray level at a first refresh rate. The operations may further include measuring, from the device, optical characteristics of the display panel for a plurality of candidate gray levels at a second refresh rate. The operations may also include selecting, from the plurality of candidate gray levels, a gray level corresponding to the input gray level based on the measured optical characteristics of the display panel for the input gray level and the plurality of candidate gray levels. The operations may further include storing, in the device, the gray level corresponding to the input gray level, wherein, after the storing step, the device is configured to adjust input display data using the gray level corresponding to the input gray level when the display panel is transitioning from the first refresh rate to the second refresh rate.

[0008] A fifth aspect provides a computer-implemented method. The method may include identifying an input gray level while a display panel of a device is operating at a first refresh rate. The method may further include retrieving, from storage on the device, a gray level corresponding to the input gray level, the corresponding gray level selected from a plurality of candidate gray levels based on measured optical characteristics of the display panel of the device for the input gray level and the plurality of candidate gray levels at the first refresh rate and a second refresh rate. The method may also include adjusting input display data using the gray level corresponding to the input gray level. The method may further include transitioning the display panel from the first refresh rate to the second refresh rate based on the adjusted input display data.

[0009] In a sixth aspect, a system is provided. The system may include one or more processors. The system may also include data storage having stored thereon computer-executable instructions that, when executed by the one or more processors, cause the system to perform operations. The operations may include identifying an input gray level while a display panel of a device is operating at a first refresh rate. The operations may further include retrieving, from storage on the device, a gray level corresponding to the input gray level, the corresponding gray level selected from a plurality of candidate gray levels based on measured optical characteristics of the display panel of the device for the input gray level and the plurality of candidate gray levels at the first refresh rate and the second refresh rate. The operations may also include adjusting input display data using the gray level corresponding to the input gray level. The operations may further include transitioning the display panel from the first refresh rate to the second refresh rate based on the adjusted input display data.

[0010] In a seventh aspect, a device is provided. The device includes one or more processors operable to perform operations. These operations may include identifying an input gray level while a display panel of the device is operating at a first refresh rate. These operations may further include retrieving, from storage in the device, a gray level corresponding to the input gray level, the corresponding gray level selected from a plurality of gray level candidates based on measured optical characteristics of the display panel of the device for the input gray level and the plurality of gray level candidates at the first refresh rate and a second refresh rate. These operations may also include adjusting input display data using the gray level corresponding to the input gray level. These operations may further include transitioning the display panel from the first refresh rate to the second refresh rate based on the adjusted input display data.

[0011] In an eighth aspect, an article of manufacture is provided. The article may include a non-transitory computer-readable medium having program instructions stored thereon, which, when executed by one or more processors of the computing device, cause the computing device to perform operations. The operations may include identifying an input gray level while a display panel of the device is operating at a first refresh rate. The operations may further include retrieving, from storage on the device, a gray level corresponding to the input gray level, the corresponding gray level selected from a plurality of candidate gray levels based on measured optical characteristics of the display panel of the device for the input gray level and the plurality of candidate gray levels at the first refresh rate and the second refresh rate. The operations may also include adjusting input display data using the gray level corresponding to the input gray level. The operations may further include transitioning the display panel from the first refresh rate to the second refresh rate based on the adjusted input display data.

[0012] Other aspects, embodiments, and implementations will become apparent to those skilled in the art from a reading of the following detailed description, taken in conjunction with the accompanying drawings where appropriate. [Brief explanation of the drawings]

[0013] [Figure 1] 10 is a table illustrating brightness values ​​for various gray levels, according to an example embodiment. [Figure 2] FIG. 10 is a diagram illustrating luminance values ​​for various gray levels at 60 Hz and 90 Hz according to an example embodiment. [Figure 3] 10 is a graph illustrating the relationship between luminance values ​​and gray levels, according to an example embodiment. [Figure 4] 10 is a graph illustrating adjustment of input data, according to an example embodiment. [Figure 5] 10 is a table illustrating luminance value increments before and after calibration according to an example embodiment. [Figure 6] FIG. 10 illustrates a lookup table in accordance with an example embodiment. [Figure 7] 10 is another graph illustrating adjustment of input data in accordance with an example embodiment. [Figure 8] 10 is a graph illustrating the increment in luminance values ​​before and after calibration according to an example embodiment. [Figure 9] FIG. 10 depicts an offset table in accordance with an example embodiment. [Figure 10] FIG. 1 illustrates a computing device according to an example embodiment. [Figure 11A] 1 is a graph illustrating a 60 Hz gamma curve for various display brightness value (DBV) bands, according to an example embodiment. [Figure 11B] 10 is a graph illustrating a 90 Hz gamma curve for DBV band 6, according to an example embodiment. [Figure 12] FIG. 1 illustrates a method according to an example embodiment. [Figure 13]FIG. 10 illustrates another method according to an example embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Detailed Description Example methods, devices, products, and systems are described herein. As used herein, the words "exemplary" and "exemplary" should be understood to mean "serving as an example, instance, or illustration." Any embodiment or feature described herein as "exemplary" or "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or features. Other embodiments may be utilized, and other changes may be made, without departing from the scope of the subject matter presented herein.

[0015] Accordingly, the exemplary embodiments described herein are not meant to be limiting, and the aspects of the present disclosure as generally described and illustrated in the figures herein can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are contemplated herein.

[0016] Furthermore, unless the context suggests otherwise, the features shown in each of the figures may be used in combination with one another. Thus, the figures should generally be viewed as components of aspects of one or more overall embodiments, with the understanding that each embodiment does not require all of the features shown. I. Overview A high display refresh rate (e.g., 90 Hz or 120 Hz) for a computing device's display panel can be desirable when running visually complex software applications, such as video or gaming applications. However, a higher refresh rate also increases the computing device's power consumption. To strike a good balance between performance and battery life, some display panels are capable of operating at one of several different refresh rates (e.g., 10 Hz, 30 Hz, 60 Hz, 90 Hz, and 120 Hz). That is, the display panel can switch between several refresh rates depending on the application being run.

[0017] However, different refresh rates can result in different optical characteristics. Specifically, the brightness and color of a display panel can differ between 60 Hz and 90 Hz. When the display panel switches from 60 Hz to 90 Hz (or from 90 Hz to 60 Hz), this optical difference can manifest as visual flicker on the display panel. As a result, if the refresh rate of a display panel frequently switches between 60 Hz and 90 Hz, the visual flicker can become noticeable, potentially disrupting the user experience. Furthermore, because the human eye is very sensitive to changes in low brightness settings, visual flicker is particularly noticeable when the brightness of the display panel is low and / or when there is little ambient light in the environment surrounding the display panel.

[0018] Some solutions attempt to solve this "flicker problem" by disabling transitions between 60 Hz and 90 Hz when the display panel's brightness is low. However, a problem with these solutions is that the definition of what is considered "low display brightness" can be quite high. In some exemplary computing devices, the ideal transition threshold for mitigating all flicker has been found to be 75%. In other words, when the display panel's brightness is equal to or greater than 75% of the display panel's total possible brightness, transitions between 60 Hz and 90 Hz are acceptable. When the display panel's brightness is less than 75% of the total possible brightness, transitions between 60 Hz and 90 Hz are not acceptable. However, users often keep the display panel's brightness below 75%, thereby minimizing the benefits of using multiple refresh rates.

[0019] One way to achieve a smooth transition from a first refresh rate to a second refresh rate of a display panel is to minimize differences in the optical properties of the display panel at all gray levels and brightness settings during the transition. As used herein, the term "optical properties" may refer to any measurable characteristic of an image displayed by a device. For example, optical properties may refer to the color or brightness values ​​of a display panel when the device displays an image or when the device transitions between different refresh rates. Also, for example, optical properties may refer to properties such as levels of refraction, absorption, scattering, and reflection.

[0020] Typically, values ​​for optical characteristics (e.g., color and brightness) may be calibrated at the factory and stored in a display driver integrated circuit (DDIC). In practice, this is performed for high brightness and high gray levels. However, such calibration for low brightness and low gray levels may require additional time ("takt time"). Generally, takt time refers to the time a manufacturer has per unit to produce enough goods to meet customer demand. Therefore, manufacturers tend to be reluctant to perform such calibration given the long takt time. Therefore, optical distortions may appear during transitions at low brightness and low gray levels. In some implementations, a blocking zone may be applied when the display is at low brightness and low gray levels, preventing the display panel from transitioning between refresh rates. However, it is desirable to eliminate the blocking zone and enable transitions for all brightness and gray levels.

[0021] Some techniques described herein address these issues by adjusting input display data using a gray level corresponding to the input gray level when a display panel of a device is transitioning from a first refresh rate to a second refresh rate. After applying these adjustments, the optical characteristics (e.g., color, brightness, etc.) of the display panel when operating at 60 Hz may be similar to the optical characteristics of the display panel when operating at 90 Hz, and therefore visual flicker that occurs when switching between 60 Hz and 90 Hz may be less noticeable. To facilitate this, the optical characteristics of the display panel with respect to the input gray level at the first refresh rate may be measured. The optical characteristics of the display panel with respect to a plurality of candidate gray levels at the second refresh rate may also be measured. A gray level corresponding to the input gray level may then be selected based on the measured optical characteristics of the display panel with respect to the input gray level and the plurality of candidate gray levels. The corresponding gray level may be selected from the plurality of candidate gray levels. The corresponding gray level may be stored in the device. The device may then be configured to adjust the input display data using a gray level corresponding to the input gray level when the display panel is transitioning from the first refresh rate to the second refresh rate.

[0022] Using the techniques described herein, multiple refresh rates may be utilized, reducing or eliminating the effects of any flicker. Other benefits are contemplated and should be understood from the discussion herein. II. EXEMPLARY TECHNIQUES FOR DETERMINING ADJUSTED INPUT DISPLAY DATA FIG. 1 is a table 100 illustrating brightness values ​​for various gray levels, according to an example embodiment. Table 100 illustrates seven Display Brightness Value (DBV) bands, DBV Band 1 through DBV Band 7. The DBVs control brightness settings of a display panel. Each DBV band corresponds to a brightness level setting. For example, Band 7 controls brightness settings from 81 nits to 500 nits of brightness, Band 6 controls brightness settings from 51 nits to 80 nits of brightness, Band 5 controls brightness settings from 26 nits to 50 nits of brightness, and so on. Generally, each pixel of a digital image may have a numerical value that represents the brightness (e.g., lightness or darkness) of the digital image at a particular spot on the display. These numerical values ​​may be referred to as "gray levels." The number of gray levels may depend on the number of bits used to represent the numerical values. For example, if 8 bits are used to represent the numerical values, a display panel may provide 256 gray levels, with a numerical value of 0 corresponding to full black and a numerical value of 255 corresponding to full white. As a more specific example, the controller may provide a display component with a digital image stream containing 24 bits, with 8 bits corresponding to gray levels for each of the red, green, and blue color channels of a pixel group.

[0023] To allow precise control of brightness levels, each DBV band may also have multiple gray levels called gamma correction points ("tap points"). For example, as shown in Table 100, each DBV band has register tap points at gray level G7, gray level G12, gray level G24, gray level G37, etc. The tap points may be at gray levels G255 through G7. For each tap point, the device may be configured with controls or knobs to control the red, green, and blue (RGB) pixel values. The RGB ratio may be balanced between 60 Hz and 90 Hz. Each DBV band and gray level corresponds to a brightness value.

[0024] For example, in DBV band 7 and gray level G7, the luminance value is 0.184 nit, and in DBV band 6 and gray level G7, the luminance value drops to 0.029 nit. In DBV band 1 and gray level G7, the luminance value drops to 0.001 nit.

[0025] There are three types of cells in table 100 based on brightness setting; the first type of cell is for high levels of brightness and is shown without shading. The brightness settings of these cells can be precisely configured (e.g., by the device manufacturer). For example, in DBV band 7, the brightness is 500 nits and the brightness level can be precisely configured for the device at all tap points except for the G7 tap point. Similarly, in DBV band 6, the brightness is 80 nits and the brightness level can be precisely configured for the device at all tap points except for the G7 and G15 tap points.

[0026] The second type of cells are those with mid-level brightness. These cells generally have brightness values ​​greater than 0.055 nits and are shaded with vertical lines. For example, in DBV band 6, tap point G15 corresponds to a mid-brightness setting. As another example, in DBV band 5, tap points G15 and G23 correspond to mid-brightness settings. For these DBV bands and tap points, the manufacturer may not have configured the brightness levels accurately, and the respective gamma values ​​at 90 Hz need to be adjusted to reduce optical defects (this is explained in more detail below). The adjusted gamma values ​​can then be stored in the device (e.g., as a lookup table) and used at runtime to change the brightness settings when the device transitions from a first refresh rate (e.g., 60 Hz) to a second refresh rate (e.g., 90 Hz).

[0027] The third type of cells are those with low brightness levels. These cells typically have luminance values ​​below 0.055 nits and are shaded with horizontal lines. For example, in DBV bands 5 and 6, tap point G7 corresponds to a low brightness setting. As another example, in DBV band 4, tap points G15 and G7 correspond to a low brightness setting. For these DBV bands and tap points, the manufacturer may not have configured the brightness levels accurately, and gamma adjustment is not possible due to the long takt time. Typically, these low brightness settings are blocked during a transition from a first refresh rate (e.g., 60 Hz) to a second refresh rate (e.g., 90 Hz). However, as described below, a device can be configured to transition smoothly between these settings by determining the luminance values ​​of the input gray levels for different refresh rates (e.g., 60 Hz and 90 Hz) and then selecting corresponding gray levels at 90 Hz for each input gray level at 60 Hz so that their optical characteristics (e.g., luminance values) are similar. These techniques can also be applied to the second type of cells. This reduces optical defects for all brightness settings and eliminates the need to block brightness settings.

[0028] For larger DBV bands and larger brightness values, the device can be accurately configured with brightness settings, and transitions can occur without difficulty. As shown in Table 100, for small DBV bands and low gray levels, brightness values ​​are very small. For example, when brightness values ​​are less than 0.055 nits, factory equipment generally cannot accurately measure such brightness levels. Therefore, for such small brightness values ​​and small DBV bands, transitions between refresh rates may be prevented in order to reduce optical defects such as flicker.

[0029] FIG. 2 illustrates luminance values ​​for various gray levels at 60 Hz and 90 Hz, according to an example embodiment. For example, an image capture device such as a colorimeter may be used to capture images of various gray levels for a fixed DBV band and various refresh rates. As shown in image 200, images may be captured at 60 Hz and 90 Hz refresh rates for gray levels 5 to 32 in an 80 nit DBV band (corresponding to band 6). In some embodiments, for a device having a display panel configured to operate at multiple refresh rates, the optical characteristics of the display panel may be measured with respect to input gray levels at a first refresh rate.

[0030] For example, a device may display an image with a fixed DBV band and gray level at a first refresh rate (e.g., 60 Hz), and a colorimeter may capture the image and measure the luminance value. Then, optical characteristics of the display panel may be measured for the image at a second refresh rate (90 Hz). For example, while the image is displayed at 60 Hz, the refresh rate for the device may be switched to 90 Hz, and the colorimeter may capture a second image and measure the luminance value at 90 Hz. The respective brightness levels at each gray level may be determined from a cross-section of each image. In some cases, depending on the calibration method of the colorimeter, the brightness level measurements may be relative values ​​between the two refresh rates rather than absolute brightness levels. In some embodiments, one or more optical characteristics may be measured at each refresh rate, and these measurements may be used individually or in combination to determine a gray level corresponding to an input gray level. For example, the corresponding gray level may be determined based on the brightness value, the color, and / or a combination of the two. Additional and / or alternative optical characteristics may be used. Also, for example, various measurements may be determined for various optical viewing distances and / or viewing angles, and such measurements may be appropriately normalized and / or averaged. For clarity, the following examples refer to specific optical properties such as luminance.

[0031] As shown in image 200, region 205 displays luminance values ​​for gray levels 13 to 32 at 60 Hz, and region 210 displays luminance values ​​for gray levels 13 to 32 at 90 Hz. As shown, there is negligible visible difference in luminance.

[0032] Region 215 displays the luminance values ​​for gray levels 5-13 at 60 Hz, and region 220 displays the luminance values ​​for gray levels 5-13 at 90 Hz. As can be seen, there are clear differences in luminance. These differences can be further analyzed graphically.

[0033] FIG. 3 is a graph illustrating the relationship between luminance values ​​and gray levels depicted in FIG. 2 , according to an example embodiment. Graph 300 is a graphical representation of the luminance values ​​displayed for DBV band 6 in FIG. 2 . The vertical axis corresponds to the measured luminance values ​​(nits), and the horizontal axis corresponds to gray levels from 5 to 32. The measured luminance values ​​for image 200 in FIG. 2 are displayed for each gray level and refresh rate at 60 Hz (corresponding points are represented by circles) and 90 Hz (corresponding points are represented by squares). As can be seen from FIG. 2 for gray levels from 13 to 32 (corresponding to regions 205 and 210 in FIG. 2 ), the luminance values ​​for the two refresh rates are nearly identical (e.g., the circles and squares nearly overlap). However, for gray levels from 5 to 13 (corresponding to regions 215 and 220 in FIG. 2 , indicated by bounding box 305), the luminance values ​​for the two refresh rates are different (e.g., the circles and squares are at distinct points).

[0034] One way to quantitatively measure the difference in luminance values ​​is to determine the luminance increment value. For example, the luminance increment can be expressed as:

[0035]

number

[0036] or

[0037]

number

[0038] It can be calculated as: 3, bounding box 305 corresponds to a brightness increment value of approximately 160%, indicating a large difference in brightness values ​​when a display panel transitions from 60 Hz to 90 Hz. Such a large brightness increment can result in optical defects such as flicker. Generally, a brightness increment percentage below a threshold is desirable to minimize flicker.

[0039] 4 is a graph illustrating adjustment of input data according to an example embodiment. Graph 400 has luminance values ​​on the horizontal axis and gray levels on the vertical axis. Luminance values ​​for various gray levels at 60 Hz are represented by circles, and luminance values ​​for gray levels at 90 Hz are represented by squares. To minimize optical artifacts, luminance increments can be reduced. One way to achieve this is to adjust the gray levels of the display to output similar luminance values ​​at different refresh rates.

[0040] As shown in graph 400, the luminance value of gray level G9 410 measured at 60 Hz is 0.028, and the luminance value measured at 90 Hz is 0.056. However, the luminance of gray level G7 405 measured at 90 Hz is 0.030. Therefore, when gray level 9 410 transitions from 60 Hz to 90 Hz, the 90 Hz gray level can be adjusted (as indicated by arrow 415) to gray level 7 405, which has a luminance value of 0.030, which is close to the luminance value of gray level 9 410 at 60 Hz, 0.028. Therefore, when the display panel of the device transitions from 60 Hz to 90 Hz, the change in luminance value is from 0.028 nits to 0.030 nits, resulting in only slight flicker. However, when the luminance value changes from 0.028 to 0.056 during the transition, the luminance increment becomes so large that it may result in a perceptible level of flicker.

[0041] As another example, the luminance value of gray level G11 420 measured at 60 Hz is 0.058, and the luminance value measured at 90 Hz is 0.081. However, the luminance of gray level G9 410 measured at 90 Hz is 0.056. Therefore, when gray level 11 420 transitions from 60 Hz to 90 Hz, the 90 Hz gray level may be adjusted (as indicated by arrow 425) to gray level 9 410, which has a luminance value of 0.056, which is close to the luminance value of gray level 11 420 at 60 Hz, 0.058. Therefore, when the display panel of the device transitions from 60 Hz to 90 Hz, the change in luminance value is from 0.058 nit to 0.056 nit, resulting in only slight flicker. However, when the luminance value changes from 0.058 to 0.081 during the transition, the luminance increment becomes so large that it may result in a perceptible level of flicker.

[0042] 5 is a table showing the increments in brightness values ​​before and after calibration, according to an example embodiment. Table 500 displays gray levels G7-G14 in column 505, along with brightness values ​​at 60 Hz (column 510) and 90 Hz (column 515). The corresponding brightness increments are displayed as percentages in column 520. Column 530 shows the brightness values ​​of the gray levels adjusted at 90 Hz. Column 535 displays the brightness increments after adjustment or calibration.

[0043] In some embodiments, the DBV band and / or input gray level may be identified as requiring adjustment and / or calibration. For example, for the gray level G14, the luminance at 60 Hz is 0.126 and the luminance at 90 Hz is 0.131. Therefore, the corresponding luminance increment may be determined to be 4.42%, which is less than the threshold percentage of luminance increment (e.g., 7%). Therefore, the gray level of G14 at 90 Hz may be determined not to require calibration.

[0044] Row 525 displays values ​​for the gray level G9. As shown in columns 510, 515, and 520, respectively, the luminance at 60 Hz is 0.028 and the luminance at 90 Hz is 0.056, resulting in a luminance increase of 95.80%. Such a large luminance increase would cause noticeable optical defects. Therefore, it can be determined that the gray level of G9 at 90 Hz requires calibration.

[0045] Calibration may be performed as shown with respect to FIG. 4. Referring to FIG. 5, optical characteristics (e.g., luminance values ​​or colors) of the display panel for a plurality of candidate gray levels at a second refresh rate (e.g., 90 Hz) are displayed in column 515. Thus, a gray level corresponding to an input gray level (e.g., G9) may be selected from the plurality of candidate gray levels. For example, for the gray level G9, the closest luminance value of 0.028 at 60 Hz among all luminance values ​​in column 515 is the luminance value 0.030 in column 510 for the gray level G7 at 90 Hz. Thus, the gray level G7 may be selected as the gray level corresponding to the input gray level of G9. Thus, as shown in row 525, the entries in column 530 are “0.030” and “G7,” and when the display panel transitions from 60 Hz to 90 Hz at the input gray level G9, the device may be calibrated to adjust the input display data using the corresponding gray level G7. After such adjustment, the brightness increment becomes 6.75%, as shown by the entry in row 525 and column 535. As used herein, the term "input display data" generally refers to values ​​used for display. For example, if the optical value is brightness, the input display data may be brightness values ​​(or lightness settings) at various gray levels. As another example, if the optical characteristic is color, the input display data may be the respective values ​​assigned to each pixel for red, blue, and green. Each optical characteristic may be associated with input display data, and such data may be adjusted and / or calibrated.

[0046] FIG. 6 illustrates a lookup table according to an example embodiment. Lookup table 600 may be determined by the process described with reference to FIG. 5. Lookup table 600 includes seven columns, designated herein as C1, C2, ..., C7. Column C1 displays a plurality of input gray levels at 60 Hz. The displayed gray levels range from 11 to 50. Column C2 displays a luminance value for each input gray level at 60 Hz, and column C3 displays a plurality of potential gray levels for each input gray level at 90 Hz. The luminance values ​​displayed in columns C2 and C3 may be determined by measurements using a colorimeter described herein. While luminance values ​​are used to provide concreteness for this description, values ​​for other optical properties may also be used. Column C4 displays a luminance value at 90 Hz after calibration, and column C5 displays the corresponding gray level at 90 Hz for each input gray level at 60 Hz. Columns C6 and C7 display the luminance increment values ​​before and after calibration, respectively.

[0047] Block 610 displays, for each input gray value in block 605, how the 60 Hz gray level value in block 605 is adjusted to obtain a corresponding gray level of 90 Hz. Similarly, block 620 displays, for each input gray value in block 615, how the 60 Hz gray level value in block 615 is adjusted to obtain a corresponding gray level of 90 Hz, and block 630 displays, for each input gray value in block 625, how the 60 Hz gray level value in block 625 is adjusted to obtain a corresponding gray level of 90 Hz. It may be noted that such adjustments depend on the optical characteristics of the device's display panel.

[0048] As described with reference to FIG. 5 , for an input gray level, a gray level corresponding to the input gray level may be selected based on the measured optical characteristics of the display panel for the input gray level and multiple candidate gray levels. The corresponding gray level is selected from multiple candidate gray levels. For example, considering block 605 as an example, for input gray level 48 in column C1 and row 635, the corresponding luminance value at 60 Hz is 0.1302 (column C2), and the luminance value at 90 Hz is 0.1171 (column C3). The luminance increment value before calibration is 10.04% (column C6). Therefore, gray level 48 may be identified as an input gray level whose luminance value at 90 Hz needs to be adjusted. In the exemplary implementation, the luminance value at 90 Hz closest to the luminance value of 0.1302 for input gray level 48 at 60 Hz is selected from the luminance values ​​of multiple candidate gray levels (column C3). Therefore, a luminance value of 0.1281 (column C4) is selected, which in turn selects 50 (column C5) as the corresponding gray level. A comparison of the luminance increment values ​​in columns C6 and C7 shows that the luminance increment has decreased from 10.04% before calibration to 1.61% after calibration. This results in the desired reduction in optical defects when adjusting the input display data using the corresponding gray levels during the transition of the display panel from 60 Hz to 90 Hz.

[0049] As another example, continuing to consider block 605, for an input gray level of 33 in column C1 and row 640, for example, the corresponding luminance value at 60 Hz is 0.0543 (column C2), and the luminance value at 90 Hz is 0.0476 (column C3). The luminance increment value before calibration is 12.34% (column C6). Therefore, gray level 33 can be identified as another input gray level whose luminance value at 90 Hz needs to be adjusted. In the example implementation, the luminance value at 90 Hz is selected from the luminance values ​​of multiple candidate gray levels (column C3) by the luminance value that is closest to the luminance value of 0.0543 for input gray level 33 at 60 Hz. Therefore, the luminance value 0.0545 (column C4) is selected, thereby selecting 35 (column C5) as the corresponding gray level. A comparison of the luminance increment values ​​in columns C6 and C7 indicates that the luminance increment has decreased from 12.34% before calibration to 0.39% after calibration. This results in the desired reduction of optical defects when adjusting the input display data using the corresponding gray levels while transitioning the display panel from 60 Hz to 90 Hz.

[0050] Considering the input gray levels in block 615, input gray level 21 having a luminance value of 0.0190 at 60 Hz is mapped to corresponding gray level 23 having a luminance value of 0.0194 at 90 Hz, thereby reducing the corresponding luminance increment from 15.79% to 1.86%. As another example, input gray level 20 having a luminance value of 0.0171 at 60 Hz is mapped to corresponding gray level 21 having a luminance value of 0.0160 at 90 Hz, thereby reducing the corresponding luminance increment from 11.81% to 6.09%. Also, for example, input gray level 19 having a luminance value of 0.0153 at 60 Hz is mapped to corresponding gray level 20 having a luminance value of 0.0151 at 90 Hz, thereby reducing the corresponding luminance increment from 10.51% to 1.49%.

[0051] Considering the input gray levels in block 625, an input gray level 17 having a luminance value of 0.0122 at 60 Hz is mapped to a corresponding gray level 17 having a luminance value of 0.0119 at 90 Hz, thereby leaving the corresponding luminance increment unchanged at 2.65%. As shown in block 630, for each input gray level at 60 Hz in block 625, the corresponding gray level at 90 Hz remains unchanged.

[0052] In some embodiments, at least one difference in an optical characteristic (e.g., luminance increment) of the display panel between the first refresh rate and the second refresh rate for a second input gray level may be measured from the device. It may be determined that the at least one difference exceeds an optical threshold. In such a case, selection of a corresponding gray level for the second input gray level may be initiated. For example, adjustment of the input display data for the input gray level may be determined by determining whether the pre-calibration luminance increment (column C6) exceeds a predetermined threshold (e.g., 6%). For example, for input gray levels from 18 to 50, it may be determined that the pre-calibration luminance increment exceeds 6%, so that the input display data is adjusted. However, for input gray levels from 11 to 17, it may be determined that the pre-calibration luminance increment does not exceed 6%, so that the input display data is not adjusted.

[0053] FIG. 7 is another graph illustrating adjustment of input data, according to an example embodiment. Graph 700 is a graphical representation of luminance values ​​for a 25-nit DBV band at 60 Hz and 90 Hz before and after calibration. For example, these values ​​may correspond to the luminance values ​​displayed in lookup table 600 of FIG. 6. The horizontal axis corresponds to input gray levels from 11 to 50 (column C1 of lookup table 600 of FIG. 6), and the vertical axis corresponds to luminance values ​​(nits). Luminance values ​​at 60 Hz (corresponding to column C2 of lookup table 600 of FIG. 6) are represented by triangles, pre-calibration luminance values ​​at 90 Hz (corresponding to column C3 of lookup table 600 of FIG. 6) are represented by circles, and post-calibration luminance values ​​at 90 Hz (corresponding to column C4 of lookup table 600 of FIG. 6) are represented by crosses. For input gray levels 11-17 (corresponding to the gray levels in block 625 of FIG. 6), the luminance values ​​at 60 Hz, the pre-calibration luminance values ​​at 90 Hz, and the post-calibration luminance values ​​at 90 Hz are identical, as indicated by the corresponding triangles, circles, and crosses that coincide. However, for gray levels 18-50, the luminance values ​​at 60 Hz and the luminance values ​​at 90 Hz appear distinct. Therefore, the luminance values ​​at 90 Hz are adjusted for these input gray levels so that the corresponding crosses and triangles appear identical, indicating that the adjusted luminance values ​​at 90 Hz are close to the luminance values ​​at 60 Hz for these input gray levels.

[0054] FIG. 8 is a graph showing the increment in luminance values ​​before and after calibration, according to an example embodiment. Graph 800 is a graphical representation of the luminance increment values ​​for a 25 nit DBV band before and after calibration. For example, these values ​​may correspond to the luminance increment values ​​displayed in lookup table 600 of FIG. 6. The horizontal axis corresponds to input gray levels 11-50 (column C1 of lookup table 600), and the vertical axis corresponds to the luminance increment value (%). The luminance increment values ​​before calibration at 90 Hz (corresponding to the values ​​in column C6 of lookup table 600 of FIG. 6) are represented by triangles, and the luminance increment values ​​after calibration at 90 Hz (corresponding to the values ​​in column C7 of lookup table 600 of FIG. 6) are represented by squares. As shown, for input gray levels 11-17 (corresponding to the gray levels in block 625 of FIG. 6), the luminance values ​​at 90 Hz are not adjusted and the luminance increment values ​​remain unchanged. However, the luminance values ​​before and after calibration at 90 Hz appear different for gray levels 18-50. The threshold (e.g., 6%) indicated by line 805 shows how gray levels that have luminance increment values ​​above the threshold (e.g., 6%) at 90 Hz can be adjusted to reduce the luminance increment values ​​below the desired threshold.

[0055] Similar techniques may be used when the display panel transitions from the second refresh rate to the third refresh rate. For example, the optical characteristics of the display panel for input gray levels at the third refresh rate may also be measured. For example, when transitioning from 90 Hz to 120 Hz, luminance values ​​at 120 Hz may be measured for the input gray levels, and a column of values ​​similar to column C3 in FIG. 6 may be generated. This results in a second plurality of candidate gray levels. Similar to the process described herein, for a given input gray level, the luminance value at 120 Hz may be compared with the luminance value at 90 Hz, and a second corresponding gray level for the input gray level may be selected based on the gray level corresponding to the input gray level (e.g., at 90 Hz) and the second plurality of candidate gray levels at the third refresh rate (e.g., 120 Hz). A mapping between the input gray levels corresponding to the gray levels and the second corresponding gray levels may be stored. During execution, the device is configured to adjust the input display data using a second gray level corresponding to the input gray level when the display panel is transitioning from the second refresh rate to a third refresh rate. III. Illustrative Gamma Correction For a particular DBV band, optical characteristics at input gray levels and candidate gray levels may be measured. In some embodiments, such measurements may be performed for all input gray levels in the selected DBV band. Also, for example, in some embodiments, a luminance increment value may be determined after the measurements, and DBV bands and input gray levels may be identified based on the luminance increment value exceeding a predetermined threshold.

[0056] 1, some brightness settings in a particular DBV band may remain unchanged. For example, unshaded cells in table 100 correspond to brightness levels that do not need to be changed. Typically, such brightness levels correspond to larger DBV bands and larger gray level tap points. For example, tap point 255 has no brightness settings that need to be adjusted.

[0057] In some embodiments, the input gray level may be based on a determination that the optical characteristic is below an optical threshold. Referring again to FIG. 1, the optical threshold may be a luminance value of 0.055 nits. Thus, at tap point G7, the input gray levels in DBV bands 1-6 may be identified for adjustment. Similarly, at tap point G15, the input gray levels in DBV bands 1-4 may be identified for adjustment, at tap point G23, the input gray levels in DBV bands 1-3 may be identified for adjustment, and so on. These cells correspond to a third type of cells having a low brightness setting and are indicated by shading with horizontal lines.

[0058] In some embodiments, when an optical characteristic exceeds an optical threshold, another technique may be applied for adjustment. Referring again to FIG. 1 , at tap point G7 and DBV band 7, the brightness value is 0.184, exceeding the exemplary optical threshold of 0.055. As another example, in DBV band 5, tap points G15 and G23 have brightness values ​​of 0.098 and 0.251, respectively, exceeding the exemplary optical threshold of 0.055. These cells correspond to a second type of cell with an intermediate brightness setting and are shown with shading including vertical lines. Therefore, the techniques disclosed herein may be applied to input gray levels at these brightness settings. However, as described below, another set of techniques may also be applied to calibrate the optical characteristic.

[0059] To vary the refresh rate between 60 Hz and 90 Hz without being noticeable to the user, it may be desirable to change the gamma values ​​in a gamma table (e.g., table 100 in FIG. 1) so that the brightness increment between 60 Hz and 90 Hz decreases, on average, over the selected input gray level. Because the human eye is very sensitive to changes in low brightness settings, some embodiments may involve changing the gamma values ​​only for low input gray level thresholds, e.g., G48 and below.

[0060] To change the gamma value of a tap point in table 100, some implementations involve changing one or more register values ​​in the display adjustment circuit 1020 of FIG. 9. For example, the display adjustment circuit 1020 may include a set of hardware registers for each tap point in table 100. The display adjustment circuit 1020 may use the values ​​in these registers to change the input gray level signal sent from the controller 1060 to the display panel 1010. Generally, the number of hardware registers for a given tap point corresponds to the number of color channels used by the display panel 1010. For example, if the display panel 1010 uses RGB color channels, the display adjustment circuit 1020 may contain three hardware registers for the given tap point, with each of the three registers corresponding to one of the RGB color channels.

[0061] To modify the gamma values ​​in table 100, an offset may be applied to a given color channel so that the register value at a refresh rate (60 Hz) is similar to the register value at a refresh rate (90 Hz). The magnitude of this offset may be determined based on the luminance increment. For example, if the luminance increment between 60 Hz and 90 Hz for an input gray level is 25%, the register value for the green color channel at 90 Hz will be significantly larger than the register value for the green color channel at 60 Hz. Therefore, a larger offset may be applied. Alternatively, if the luminance increment between 60 Hz and 90 Hz for an input gray level is 10%, the register value for the green color channel at 90 Hz will be relatively similar to the register value for the green color channel at 60 Hz, and therefore a smaller offset may be applied.

[0062] In some embodiments, at least one difference in an optical characteristic of the display panel between the first refresh rate and the second refresh rate for an input gray level may be measured. In general, the magnitude of the gamma offset may vary depending on the luminance increment (or another measured difference in optical characteristic) for the input gray level. Some embodiments may include a series of offset tables that list offset values ​​to apply to various luminance increments. In some implementations, these offset tables are determined based on an analysis of devices containing display panels similar to display panel 1010 (perhaps devices developed by the manufacturer that developed display panel 1010).

[0063] 9 includes various example offset tables according to example embodiments. That is, FIG. 9 includes four offset tables: offset table 910, offset table 920, offset table 930, and offset table 940. Each of these offset tables may be used to identify an offset value to apply to various brightness increments in brightness increment table 900.

[0064] In some embodiments, when the display panel is operating at a second refresh rate, an offset value may be applied to a default gamma value used by the device for input gray levels based on at least one measured difference, thereby generating a new gamma value. In some embodiments, the display panel may include multiple color channels, and the default gamma value may include respective register values ​​for the multiple color channels. In such cases, the offset value may include an offset for at least one of the register values ​​of the default gamma value. The multiple color channels may include red, green, and blue (RGB) color channels. For example, when the value of the brightness increment 902 is determined to be −15.446, the offset table 920 may be used to determine that the value of −15.446 is in the range [−15.5, −13], and therefore an offset value of 1 should be applied to the green color channel register value for DVB band 4 / input gray level G15 at 90 Hz. As another example, luminance increment 904 is the luminance increment for DVB band 2 / input gray level G15. When the value of luminance increment 904 is determined to be 12.67, offset table 940 may be used to determine that the value of 12.67 is in the range of [7,14], and therefore an offset value of −1 should be applied to the green color channel register for DVB band 2 / input gray level G15 at 90 Hz, an offset value of 1 should be applied to the red color channel register for DVB band 2 / input gray level G15 at 90 Hz, and an offset value of 1 should be applied to the blue color channel register for DVB band 2 / input gray level G15 at 90 Hz.

[0065] In some embodiments, the device is configured to store the new gamma value and subsequently replace the default gamma value for the second input gray level with the new gamma value when the display panel operates at the second refresh rate. In some embodiments, a process occurs in which the register value for the input gray level is updated until the luminance increment for the input gray level is less than a predetermined threshold. In some examples, the predetermined threshold is between 5% and 95%. For example, the predetermined threshold may be 5%, 10%, or 90%.

[0066] In certain embodiments, a process of updating register values ​​for input gray levels occurs until (i) the increment in luminance for the input gray level is below a predetermined threshold, and (ii) the increment in color difference for the input gray level is below a predetermined color threshold, where color difference is measured as a linear combination of the squared difference between u' at 90 Hz and u' at 60 Hz and the squared difference between v' at 90 Hz and v' at 60 Hz, where u' and v' are color coordinates in the CIELUV color space. For example, color difference can be expressed as:

[0067]

number

[0068] It can be measured as: In some cases, the predetermined color threshold may be 0.4%, i.e., it may be desirable to keep Δ(u′,v′) below 0.004. In some cases, even with small luminance increments, the color difference is large and the optical defect remains perceptible. Therefore, in some embodiments, both luminance and color may need to be adjusted to achieve better results. During the measurement of the optical properties, both luminance and color changes may be recorded and / or monitored. The color difference may be measured in a manner similar to the measurement of the luminance increment. IV. Exemplary Devices 10 illustrates a computing device 1000 according to an example embodiment. The computing device 1000 includes a display panel 1010, a display adjustment circuit 1020, one or more ambient light sensors 1030, one or more other sensors 1040, a network interface 1050, and a controller 1060. In some examples, the computing device 1000 may take the form of a desktop device, a server device, or a mobile device. The computing device 1000 may be configured to interact with an environment. For example, the computing device 1000 may obtain measurements of environmental conditions associated with the environment around the computing device 1000 (e.g., temperature measurements, ambient light measurements, etc.).

[0069] The display panel 1010 may be configured to provide output signals to a user as a display using one or more screens (including touch screens), cathode ray tubes (CRTs), liquid crystal displays (LCDs), light emitting diodes (LEDs), digital light processing (DLP) technology, and / or other similar technologies. The display panel 1010 may also be configured to generate audible output, such as with speakers, speaker jacks, audio output ports, audio output devices, earphones, and / or other similar devices. The display panel 1010 may further be configured with one or more tactile components capable of generating tactile output, such as vibrations and / or other outputs detectable upon touch and / or physical contact with the computing device 1000.

[0070] In an exemplary embodiment, the display panel 1010 is configured to provide an output signal at a given refresh rate. The refresh rate may correspond to the number of times per second that the display panel 1010 updates with new content. For example, a refresh rate of 60 Hz may mean that the display panel 1010 updates 60 times per second. In an exemplary embodiment, the display panel 1010 may operate at refresh rates of 60 Hz, 90 Hz, or 120 Hz, among others.

[0071] In certain embodiments, the display panel 1010 may be a color display that utilizes multiple color channels to generate an image. For example, the display panel 1010 may utilize red, green, and blue (RGB) color channels, or cyan, magenta, yellow, and black (CMYK) color channels, among others. As described herein, the display adjustment circuit 1020 may adjust the input display data using a gray level corresponding to the input gray level when the display panel is transitioning from a first refresh rate to a second refresh rate. As further described herein, the display adjustment circuit 1020 may adjust the gamma characteristics for each of the color channels of the display panel 1010, as described with reference to FIG. 9 .

[0072] In some embodiments, the display panel 1010 may include a plurality of pixels arranged in a pixel array defining a plurality of rows and columns. For example, if the display panel 1010 has a resolution of 1024x600, each column of the array may include 600 pixels, and each row of the array may include 1024 pixel groups, with each group including a red pixel, a blue pixel, and a green pixel, for a total of 3072 pixels per row. In an example embodiment, the color of a particular pixel may depend on a color filter disposed over the pixel.

[0073] In an exemplary embodiment, the display panel 1010 may receive image data from the controller 1060 and, in response, send signals to the pixel array of the display panel 1010 to display the image data. To send the image data to the display panel 1010, the controller 1060 may first convert the digital image into numerical data that the display panel 1010 can interpret. For example, the digital image may contain various image pixels corresponding to each pixel of the display panel 1010. Each pixel of the digital image may have a numerical value that represents the brightness (e.g., lightness or darkness) of the digital image at a particular spot. These numerical values ​​may be referred to as "gray levels." The number of gray levels may depend on the number of bits used to represent the numerical values. For example, if 8 bits are used to represent the numerical values, the display panel 1010 may provide 256 gray levels, with a numerical value of 0 corresponding to full black and a numerical value of 255 corresponding to full white. As a more specific example, the controller 1060 may provide the display panel 1010 with a digital image stream containing 24 bits, with 8 bits corresponding to gray levels for each of the red, green, and blue color channels of a pixel group.

[0074] In some cases, the brightness characteristics of an image displayed by the display panel 1010 may be inaccurately represented as perceived by a user. Such inaccuracies may arise from the nonlinear response of the human eye and may cause an inaccurate depiction of color / brightness on the display panel 1010 from the user's perspective. To compensate for such inaccuracies, the computing device 1000 may use a display adjustment circuit 1020.

[0075] The display adjustment circuit 1020 may include circuitry that can compensate for inaccuracies that occur when displaying images on the display panel 1010. To do this, the display adjustment circuit may include a memory for storing one or more gamma curves / tables, the values ​​of each curve / table being determined based on the transmission sensitivity of the display panel 1010 over a range of input gray levels.

[0076] As an illustrative example, FIG. 11A shows a graph 1100 including various gamma curves. Each gamma curve may correspond to a display brightness value (DBV) band. Based on user input, a particular DBV band (and therefore a particular gamma curve) may be used. For example, a user may select a maximum brightness for the display panel 1010, perhaps by interacting with a brightness adjustment bar. Based on that maximum brightness, the display panel 1010 may select a corresponding DBV band (and therefore a corresponding gamma curve) to compensate for inaccuracies that occur when displaying an image.

[0077] As shown in graph 1100, each gamma curve includes a relationship between input gray level (x-axis) and the luminance (y-axis) of the visible image displayed on the display panel 1010. These relationships are nonlinear. For example, in band 7, an input gray level of 1100 corresponds to a luminance value of 300 nits. By adjusting the input gray level using a gamma curve, the image displayed on the display panel 1010 may result in a luminance that has a nonlinear relationship to the input gray level. However, when a user views the displayed image, the human eye response may still perceive it as having a linear relationship between luminance and the input gray level. Therefore, by using a gamma curve, the display panel 1010 can generate an image that a user may perceive as having an overall linear relationship between input gray level and luminance.

[0078] The display panel 1010 may use different gamma curves depending on whether it operates at a first refresh rate (e.g., 60 Hz) or a second refresh rate (e.g., 90 Hz). For example, when operating at 60 Hz, the display panel 1010 may utilize the gamma curve shown in graph 1100. On the other hand, when operating at 90 Hz, the display panel 1010 may utilize the gamma curve shown in graph 1110 of FIG. 11B. For clarity, graph 1110 only includes the gamma curve for DBV band 6. However, it should be noted that graph 1110 may also include other gamma curves for other DBV bands.

[0079] The gamma curve for 60 Hz may differ from the gamma curve for 90 Hz. For example, the gamma curve for DBV band 6 in graph 1100 differs from the gamma curve for DBV band 6 in graph 1110. More specifically, the gamma curve for DBV band 6 in graph 1110 has, on average, a larger luminance value for the input gray level than the gamma curve for DBV band 6 in graph 1100. In line with the above discussion, this difference may cause visual flicker to appear on the display panel 1010 when the display panel 1010 transitions from 60 Hz to 90 Hz (and also when transitioning from 90 Hz to 60 Hz). Consequently, if the refresh rate of the display panel 1010 frequently switches between 60 Hz and 90 Hz, the visual flicker may become noticeable, potentially detracting from the user's experience. Furthermore, because the human eye is very sensitive at low brightness settings, the visual flicker is particularly noticeable when the brightness of the display panel 1010 is low.

[0080] 10 , the ambient light sensor 1030 may be configured to receive light from the environment (e.g., within 1 meter, within 5 meters, or within 10 meters) of the computing device 1000. The ambient light sensor 1030 may include one or more single-photon avalanche detectors (SPADs), avalanche photodiodes (APDs), complementary metal-oxide semiconductor (CMOS) detectors, and / or charge-coupled devices (CCDs). For example, the ambient light sensor 1030 may include an indium gallium arsenide (InGaAs) APD configured to detect light at a wavelength of approximately 1550 nm. Other types of ambient light sensors 1030 are possible and contemplated herein.

[0081] In some embodiments, the ambient light sensor 1030 may include multiple light-sensing elements arranged in a one-dimensional or two-dimensional array. For example, the ambient light sensor 1030 may include 16 detector elements arranged in a single row (e.g., a linear array). The detector elements may be arranged along or at least parallel to a major axis.

[0082] In some embodiments, computing device 1000 may include one or more other sensors 1040. Other sensors 1040 may be configured to measure conditions internal to computing device 1000 and / or conditions of the environment (e.g., within 1 meter, within 5 meters, or within 10 meters) and provide data regarding these conditions.For example, the other sensors 1040 may include: (i) sensors for obtaining data regarding the computing device 1000, such as, but not limited to, a thermometer for measuring the temperature of the computing device 1000, a battery sensor for measuring the power of one or more batteries of the computing device 1000, and / or other sensors for measuring the condition of the computing device 1000; (ii) identification sensors for identifying other objects and / or devices, such as, but not limited to, a radio frequency identification (RFID) reader, a proximity sensor, a one-dimensional barcode reader, a two-dimensional barcode (e.g., a quick response (QR) code) reader, and / or a laser tracker, which may be configured to read an RFID tag, a barcode, a QR code, and / or an identifier configured to be read from other devices and / or objects, etc., to provide at least identification information; and (iii) a location and / or a position of the computing device 1000. (iv) sensors such as, but not limited to, tilt sensors, gyroscopes, accelerometers, Doppler sensors, global positioning system (GPS) devices, sonar sensors, radar devices, laser displacement sensors, and / or compasses to measure movement; (iv) environmental sensors such as, but not limited to, infrared sensors, light sensors, biosensors, capacitive sensors, touch sensors, temperature sensors, wireless sensors, radio sensors, motion sensors, proximity sensors, radar receivers, microphones, sound sensors, ultrasonic sensors, and / or smoke detectors to obtain data indicative of the environment of computing device 1000; and (v) force sensors such as, but not limited to, one or more sensors measuring force in one or more dimensions, torque, gravity, friction, and / or a zero moment point (ZMP) sensor to identify the ZMP and / or its location to measure one or more forces (e.g., inertial forces and / or G-forces) acting about computing device 1000. Many other examples of other sensors 1040 are possible as well.

[0083] Data collected from the ambient light sensor 130 and other sensors 1040 may be communicated to a controller 1060, which uses the data to perform one or more actions.

[0084] The network interface 1050 may include one or more wireless and / or wired interfaces configurable to communicate over a network. The wireless interface may include one or more wireless transmitters, receivers, and / or transceivers, such as a Bluetooth™ transceiver, a Zigbee™ transceiver, a Wi-Fi™ transceiver, a WiMAX™ transceiver, and / or other similar types of wireless transceivers configurable to communicate over a wireless network. The wired interface may include one or more wired transmitters, receivers, and / or transceivers, such as an Ethernet transceiver, a Universal Serial Bus (USB) transceiver, or similar transceiver, configurable to communicate over twisted pair wire, coaxial cable, fiber optic link, or similar physical connection to a wired network.

[0085] In some embodiments, the network interface 1050 may be configured to provide reliable, secure, and / or authenticated communications. For each communication described herein, information (e.g., packet / message sequencing information, encapsulation headers and / or footers, size / time information, and transmission verification information such as cyclic redundancy check (CRC) and / or parity check values) may be provided, perhaps as part of the message header and / or footer, to facilitate reliable communications (e.g., guaranteed message delivery). Communications may be secured (e.g., encoded or encrypted) and / or decrypted / decoded using one or more cryptographic protocols and / or algorithms, such as, but not limited to, the Data Encryption Standard (DES), the Advanced Encryption Standard (AES), the Rivest-Shamir-Adelman (RSA) algorithm, the Diffie-Hellman algorithm, a secure socket protocol such as Secure Sockets Layer (SSL), Transport Layer Security (TLS), and / or the Digital Signature Algorithm (DSA). Other cryptographic protocols and / or algorithms may be used to secure (and then decrypt / decrypt) communications similar to or in addition to those enumerated herein.

[0086] The controller 1060 may include one or more processors 1062 and a memory 1064. The processor 1062 may include one or more general-purpose processors and / or one or more special-purpose processors (e.g., display driver integrated circuits (DDICs), digital signal processors (DSPs), tensor processing units (TPUs), graphics processing units (GPUs), application-specific integrated circuits (ASICs), etc.). The processor 1062 may be configured to execute computer-readable instructions contained in the memory 1064 and / or other instructions as described herein.

[0087] The memory 1064 may include one or more non-transitory computer-readable storage media that can be read and / or accessed by the processor(s) 1062. The one or more non-transitory computer-readable storage media may include volatile and / or non-volatile storage components, such as optical, magnetic, organic, or other memory or disk storage, that may be integrated in whole or in part with at least one of the processors 1062. In some examples, the memory 1064 may be implemented using a single physical device (e.g., one optical, magnetic, organic, or other memory or disk storage unit), while in other examples, the memory 1064 may be implemented using two or more physical devices.

[0088] In the illustrated embodiment, processor 1062 is configured to execute instructions stored in memory 1064 to perform operations.

[0089] These operations may include identifying an input gray level while the display panel 1010 is operating at a first refresh rate.

[0090] These operations may further include retrieving a gray level corresponding to the input gray level from storage (e.g., memory 1064) of computing device 1000. The corresponding gray level may be selected from a plurality of candidate gray levels based on measured optical characteristics of display panel 1010 for the input gray level and a plurality of candidate gray levels at the first refresh rate and the second refresh rate. For example, the optical characteristics of display panel 1010 for the input gray level at the first refresh rate may have been measured. For example, the optical characteristics of display panel 1010 for the plurality of candidate gray levels at the second refresh rate may also have been measured. This may involve measurements by an image capture device (e.g., a spectrophotometer or colorimeter) separate from computing device 1000 and configured to measure optical characteristics. In some embodiments, one or more optical characteristics may be measured.

[0091] These operations may also include adjusting the input display data using a gray level corresponding to the input gray level.

[0092] These operations may also include transitioning the display panel 1010 from a first refresh rate to a second refresh rate based on the adjusted input display data. For example, the controller 1060 may transition the refresh rate of the display panel 1010 from 60 Hz to 90 Hz, or from 90 Hz to 60 Hz.

[0093] These operations may further include identifying a rate change triggering event while the display panel 1010 is operating at the first refresh rate. Transitioning the display panel 1010 from the first refresh rate to the second refresh rate may be performed in response to identifying the rate change triggering event. In some embodiments, the rate change triggering event may be initiated by a process running on the device (e.g., brightness settings for various applications, time of day specification, etc.). In some embodiments, the rate change triggering event may include a user interaction with the display panel 1010 (e.g., a fingerprint detection event in which the computing device 1000 attempts to authenticate the user's fingerprint). In some embodiments, the rate change triggering event may be based on environmental condition measurements (e.g., by the ambient light sensor 1030 and / or other sensors 1040) related to the environment around the computing device 1000.

[0094] The operations may further include detecting an end of the rate change triggering event after the display panel 1010 transitions from the first refresh rate to the second refresh rate. The operations may then include transitioning the display panel 1010 from the second refresh rate to the first refresh rate in response to detecting an end of the rate change triggering event. V. Illustrative Methods 12 illustrates a method 1200 according to an example embodiment. The method 1200 may include various blocks or steps. The blocks or steps may be performed individually or in combination. The blocks or steps may be performed in any order and / or sequentially or in parallel. Additionally, the method 1200 may omit or add blocks or steps.

[0095] Some or all of the blocks of method 1200 may be performed by various elements of computing device 1000. Alternatively, or in addition, some or all of the blocks of method 1200 may be performed by a computing device communicatively coupled to computing device 1000. Moreover, some implementations of method 1200 may utilize relationships represented in the graphs and / or tables shown and described in connection with FIGS.

[0096] Block 1210 includes, for a device having a display panel configured to operate at multiple refresh rates, measuring optical characteristics of the display panel with respect to input gray levels at a first refresh rate.

[0097] Block 1220 includes measuring optical characteristics of the display panel for the device for a plurality of candidate gray levels at the second refresh rate.

[0098] Block 1230 includes selecting a gray level from the plurality of candidate gray levels that corresponds to the input gray level based on the input gray level and candidate measured optical characteristics of the display panel for the plurality of candidate gray levels.

[0099] Block 1240 includes a step of storing a gray level corresponding to the input gray level in a device, the device being configured, after the storing step, to adjust the input display data using the gray level corresponding to the input gray level when the display panel is transitioning from the first refresh rate to the second refresh rate.

[0100] In some embodiments, the measuring step may be performed for a given display brightness band of the display panel.

[0101] Some embodiments include determining a display brightness band. Such embodiments may also include determining an input gray level in the determined display brightness band. In some embodiments, the input gray level is based on determining that the optical characteristic is below an optical threshold.

[0102] In some embodiments, the second input gray level may be determined based on a determination that the optical characteristic is greater than an optical threshold. Such embodiments may also include measuring, from the device, at least one difference in the optical characteristic of the display panel between the first refresh rate and the second refresh rate for the second input gray level. Such embodiments may further include applying an offset value based on the at least one measured difference to a default gamma value used by the device for the second input gray level when the display panel operates at the second refresh rate, thereby generating a new gamma value. Such embodiments may also include storing the new gamma value in the device, wherein, after the storing step, the device is configured to replace the default gamma value for the second input gray level with the new gamma value when the display panel operates at the second refresh rate.

[0103] In some embodiments, the display panel may have multiple color channels. The default gamma value may include respective register values ​​for the multiple color channels. The offset value may include an offset for at least one of the register values ​​for the default gamma value. In some embodiments, the multiple color channels may include red, green, and blue (RGB) color channels.

[0104] In some embodiments, the offset value may be determined based at least in part on a default gamma value that the device uses for input gray levels when the display panel is operating at the first refresh rate.

[0105] In some embodiments, the measuring step may be performed by an image capture device configured to measure the optical property.

[0106] In some embodiments, the first refresh rate may be 60 Hz and the second refresh rate may be 90 Hz.

[0107] In some embodiments, the optical property may be one of the brightness or color of the display panel.

[0108] In some embodiments, the storing step may include storing, for a plurality of input gray levels, a plurality of corresponding gray levels in a boot image of the device.

[0109] Some embodiments include measuring, for the device, optical characteristics of the display panel for the second plurality of gray level candidates at the third refresh rate. Such embodiments may further include selecting a second gray level corresponding to the input gray level from the second plurality of gray level candidates based on the gray level corresponding to the input gray level and the second plurality of gray level candidates at the third refresh rate. Such embodiments may also include storing the second gray level corresponding to the input gray level in the device, wherein after the storing step, the device is configured to adjust input display data using the second gray level corresponding to the input gray level when the display panel is transitioning from the second refresh rate to the third refresh rate.

[0110] Some embodiments include measuring, from the device, at least one difference in an optical characteristic of the display panel between the first refresh rate and the second refresh rate for a second input gray level. Such embodiments may further include determining that the at least one difference exceeds an optical threshold. Such embodiments may also include initiating a step of selecting a gray level corresponding to the second input gray level.

[0111] 13 illustrates a method 1300 according to an example embodiment. The method 1300 may include various blocks or steps. The blocks or steps may be performed individually or in combination. The blocks or steps may be performed in any order and / or sequentially or in parallel. Additionally, the method 1300 may have blocks or steps omitted or added.

[0112] Some or all of the blocks of method 1300 may be performed by various elements of computing device 1000. Alternatively, or in addition, some or all of the blocks of method 1300 may be performed by a computing device communicatively coupled to computing device 1000. Moreover, some implementations of method 1300 may utilize relationships depicted in the graphs and / or tables shown and described in connection with FIGS.

[0113] Block 1310 includes identifying an input gray level while a display panel of a device is operating at a first refresh rate.

[0114] Block 1320 includes retrieving, from storage on the device, a gray level corresponding to the input gray level, the corresponding gray level selected from the plurality of gray level candidates based on measured optical characteristics of the display panel for the input gray level and the plurality of gray level candidates at the first refresh rate and the second refresh rate.

[0115] Block 1330 includes adjusting the input display data using a gray level corresponding to the input gray level.

[0116] Block 1340 includes transitioning the display panel from the first refresh rate to the second refresh rate based on the adjusted input display data.

[0117] Some embodiments include identifying a rate-change triggering event while the display panel is operating at the first refresh rate, and transitioning the display panel from the first refresh rate to the second refresh rate can be performed in response to identifying the rate-change triggering event.

[0118] In some embodiments, the triggering event for the rate change may be initiated by a process running on the device.

[0119] In some embodiments, the triggering event for the rate change may include a user interaction with the display panel.

[0120] In some embodiments, the triggering event for the rate change may be based on a measurement of an environmental condition associated with the environment around the device.

[0121] Some embodiments include detecting an end of the rate change triggering event after the display panel has transitioned from the first refresh rate to the second refresh rate. Such embodiments may include transitioning the display panel from the second refresh rate to the first refresh rate in response to detecting an end of the rate change triggering event.

[0122] The particular features shown in the figures should not be seen as limiting. It should be understood that other embodiments may include more or fewer elements than each element shown in a given figure. Moreover, some of the elements shown may be combined or omitted. Still further, example embodiments may include elements not shown in the figures.

[0123] Steps or blocks representing the processing of information may correspond to circuitry that can be configured to perform specific logical functions of the methods or techniques described herein. Alternatively, or in addition, steps or blocks representing the processing of information may correspond to modules, segments, or portions of program code (including associated data). The program code may include one or more instructions executable by a processor to implement specific logical functions or actions in the method or technique. The program code and / or associated data may be stored on any type of computer-readable medium, such as a storage device, including a disk, hard drive, or other storage medium.

[0124] Computer-readable media may also include transient computer-readable media, such as register memory, processor cache, and random access memory (RAM), which store data for a short period of time. Computer-readable media may also include non-transitory computer-readable media, which store program code and / or data for a longer period of time. Thus, computer-readable media may include secondary or persistent long-term storage, such as read-only memory (ROM), optical or magnetic disks, and compact disc-based read-only memory (CD-ROM). Computer-readable media may also be other volatile or non-volatile storage systems. Computer-readable media may be considered computer-readable storage media, such as tangible storage devices.

[0125] While various examples and embodiments have been disclosed, other examples and embodiments will be apparent to those skilled in the art. The various disclosed examples and embodiments are for purposes of illustration and not limitation, the true scope being indicated by the following claims.

Claims

1. 1. A method comprising: measuring optical characteristics of a display panel from a device having a display panel configured to operate at multiple refresh rates for an input gray level at a first refresh rate, the input gray level representing a luminance of a digital image displayed on the display panel, the gray level at which the optical characteristics of the display panel change when the display panel transitions from the first refresh rate to a second refresh rate; The method further includes measuring, from the device, the optical characteristics of the display panel for a plurality of candidate gray levels at the second refresh rate, the candidate gray levels representing luminances of a digital image displayed on the display panel and being gray levels surrounding the input gray level; The method further includes selecting a gray level corresponding to the input gray level based on the input gray level and the measured optical characteristics of the display panel for the plurality of gray level candidates, wherein the corresponding gray level is selected from the plurality of gray level candidates at the second refresh rate as a gray level having optical characteristics that are less different from the measured optical characteristics of the display panel for the input gray level at the first refresh rate; the method further comprising storing in the device a mapping between the input gray levels and the corresponding gray levels, the device being configured, after the storing step, to adjust input display data representing luminance values ​​and / or color values ​​of each pixel displayed on the display panel using the mapping between the input gray levels and the corresponding gray levels when the display panel is transitioning from the first refresh rate to the second refresh rate.

2. The method of claim 1 , wherein the measuring step is performed for a given display brightness band of the display panel.

3. determining a display brightness band; determining input gray levels in said determined display lightness band; 3. The method of claim 1 or 2, further comprising:

4. The method of claim 3 , wherein the input gray level is based on a determination that the optical property is below an optical threshold.

5. a second input gray level based on a determination that the optical characteristic is greater than an optical threshold value; is determined, and the method further comprises: measuring, from the device, at least one difference in the optical characteristic of the display panel between the first refresh rate and the second refresh rate for the second input gray level; applying an offset value based on the at least one measured difference to a default gamma value used by the device for the second input gray level when the display panel is operating at the second refresh rate, thereby generating a new gamma value; 4. The method of claim 3, further comprising: storing the new gamma value in the device; and wherein, after the storing step, the device is configured to replace the default gamma value for the second input gray level with the new gamma value when the display panel operates at the second refresh rate.

6. 6. The method of claim 5, wherein the display panel has multiple color channels, the default gamma value includes respective register values ​​for the multiple color channels, and the offset value includes an offset to at least one of the register values ​​of the default gamma value.

7. The method of claim 6 , wherein the plurality of color channels includes red, green, and blue (RGB) color channels.

8. 8. The method of claim 5, wherein the offset value is determined based at least in part on a default gamma value that the device uses for the input gray levels when the display panel is operating at the first refresh rate.

9. The method of any one of claims 1 to 8, wherein the measuring step is performed by an image capture device configured to measure the optical property.

10. The method of any one of claims 1 to 9, wherein the first refresh rate is 60 Hz and the second refresh rate is 90 Hz.

11. The method of any one of claims 1 to 10, wherein the optical property is one of the brightness or color of the display panel.

12. The method of any one of claims 1 to 11, wherein the storing step comprises storing, for a plurality of input gray levels, a plurality of corresponding gray levels in a boot image of the device.

13. measuring, from the device, the optical characteristics of the display panel for a second plurality of candidate gray levels at a third refresh rate; selecting a second gray level corresponding to the input gray level from the second plurality of gray level candidates based on the gray level corresponding to the input gray level and the second plurality of gray level candidates at the third refresh rate; and storing the second gray level corresponding to the input gray level in the device, wherein after the storing step, the device is configured to adjust the input display data using the second gray level corresponding to the input gray level when the display panel is transitioning from the second refresh rate to the third refresh rate.

14. measuring, from the device, at least one difference in the optical characteristic of the display panel between the first refresh rate and the second refresh rate for a second input gray level; determining that the at least one difference exceeds an optical threshold; initiating the step of selecting the gray level corresponding to the second input gray level; The method of any one of claims 1 to 3, further comprising:

15. identifying an input gray level while a display panel of a device is operating at a first refresh rate, the input gray level representing a luminance of a digital image to be displayed on the display panel, the gray level at which an optical characteristic of the display panel changes when the display panel transitions from the first refresh rate to a second refresh rate; and and retrieving a gray level corresponding to the input gray level from a storage of the device, wherein the corresponding gray level is selected from a plurality of candidate gray levels at a second refresh rate as a gray level having optical characteristics that are less different from the measured optical characteristics of the display panel for the input gray level at the first refresh rate, the plurality of candidate gray levels representing luminance of a digital image to be displayed on the display panel and being gray levels around the input gray level; and adjusting input display data representing luminance and / or color values ​​of each pixel displayed on the display panel using the mapping between the input gray levels and the corresponding gray levels; transitioning the display panel from the first refresh rate to the second refresh rate based on the adjusted input display data; A computer-implemented method for causing a computer to perform a method comprising:

16. further comprising identifying a rate change triggering event while the display panel is operating at the first refresh rate; 16. The method of claim 15, wherein transitioning the display panel from the first refresh rate to the second refresh rate is performed in response to identifying a triggering event for the rate change.

17. The method of claim 16 , wherein the rate change triggering event is initiated by a process running on the device.

18. The method of claim 16 or 17, wherein the triggering event for the rate change comprises a user interaction with the display panel.

19. The method of any one of claims 16 to 18, wherein the triggering event for the rate change is based on a measurement of an environmental condition relating to an environment around the device.

20. detecting an end of the rate change triggering event after the display panel transitions from the first refresh rate to the second refresh rate; transitioning the display panel from the second refresh rate to the first refresh rate in response to detecting an end of the rate change trigger event; The method of any one of claims 16 to 19, further comprising:

21. one or more processors; and a data storage, The data storage stores computer-executable instructions that, when executed by the one or more processors, cause the system to perform operations, including: A device having a display panel configured to operate at multiple refresh rates receives a signal from the display panel for input gray levels at a first refresh rate. measuring an optical characteristic of a display panel, the input gray level representing a brightness of a digital image to be displayed on the display panel, the input gray level being a gray level at which the optical characteristic of the display panel changes when the display panel transitions from the first refresh rate to a second refresh rate; The operations further include measuring, from the device, the optical characteristics of the display panel for a plurality of candidate gray levels at the second refresh rate, the candidate gray levels representing luminances of a digital image displayed on the display panel and being gray levels surrounding the input gray level; The operations further include selecting a gray level corresponding to the input gray level based on the input gray level and the measured optical characteristics of the display panel for the plurality of gray level candidates, wherein the corresponding gray level is selected as a gray level from the plurality of gray level candidates at the second refresh rate that has optical characteristics that are less different from the measured optical characteristics of the display panel for the input gray level at the first refresh rate, and the operations further include: storing a mapping between the input gray levels and the corresponding gray levels in the device, wherein the device is configured, after the storing step, to adjust input display data representing luminance values ​​and / or color values ​​of each pixel displayed on the display panel using the mapping between the input gray levels and the corresponding gray levels when the display panel is transitioning from the first refresh rate to the second refresh rate.

22. A computer program which, when executed by a computer, causes the computer to carry out the method of any one of claims 15 to 20.

23. A computer program comprising computer-executable instructions which, when executed by one or more processors included in a system, cause the system to perform a method according to any one of claims 1 to 14.

Images