Image processing method and image display device

Abstract

An image processing method includes calculating brightness information of multiple brightness gray levels of multiple pixels of image data, causing a first sub-gamma correction curve and a second sub-gamma correction curve to be combined with each other at a turning point to generate a target gamma correction curve, and setting a position of the turning point according to the brightness information. A first gamma value of the first sub-gamma correction curve is different from a second gamma value of the second sub-gamma correction curve, and a range of brightness gray levels corresponding to the first sub-gamma correction curve does not overlap with a range of brightness gray levels corresponding to the second sub-gamma correction curve.

Description

Technical Field

[0001] The present invention relates to an image processing method and an image display device, and more particularly to an image processing method and an image display device capable of dynamically adjusting a gamma correction curve. Background Art

[0002] Currently, for high-resolution applications of light-emitting diode (LED) video walls, such as 4K resolution or even 8K resolution applications, most are composed of multiple light boxes spliced together. However, the power consumption of the LED video wall will increase exponentially with the number of spliced light boxes. Taking the example of splicing LED light boxes with a resolution of 480×270 into an 8K resolution (7680×4320 resolution) LED video wall, assuming that the power consumption of a single LED light box in a bright scene is 80 watts, then for an 8K resolution LED video wall, 256 LED light boxes are required, and the power consumption is 20,480 watts, which is 256 times that of a single LED light box. Therefore, the power consumption in the application of existing high-resolution LED video walls is extremely high.

[0003] To improve the power consumption problem of high-resolution LED video wall applications, the common current practice is to linearly reduce the brightness gray scale value of each pixel of the LED video wall to achieve power saving. However, since the contrast between pixels in an image is highly correlated with the difference in brightness gray scale values between pixels in the image, if only the brightness gray scale value of each pixel of the LED video wall is linearly reduced, the difference in brightness gray scale values between pixels will also decrease, thereby reducing the contrast of the image. How to balance the power consumption of the LED video wall and the image contrast is an important issue in high-resolution LED video wall applications. Summary of the Invention

[0004] The present invention provides an image processing method and an image display device that can dynamically adjust the gamma correction curve according to the brightness information of the input image data, so as to balance the power consumption of the display screen and the contrast of the display image.

[0005] The image processing method of the present invention includes calculating the luminance information of multiple luminance gray levels of multiple pixels of image data, combining a first sub-gamma correction curve and a second sub-gamma correction curve at a turning point, and setting the position of the turning point according to the luminance information. The first sub-gamma correction curve has a first gamma value, the second sub-gamma correction curve has a second gamma value, and the first gamma value is different from the second gamma value. The first sub-gamma correction curve corresponds to a first luminance gray level range, and the second sub-gamma correction curve corresponds to a second luminance gray level range. The first luminance gray level range and the second luminance gray level range do not overlap, and any luminance gray level in the first luminance gray level range is less than any luminance gray level in the second luminance gray level range.

[0006] The image display device of the present invention includes a display screen and a controller. The display screen is used to display an output image, and the controller is coupled to the display screen. The controller is configured to receive image data, calculate the luminance information of multiple luminance gray levels of multiple pixels of the image data, combine a first sub-gamma correction curve and a second sub-gamma correction curve at a turning point, set the position of the turning point according to the luminance information, convert multiple luminance gray levels of the image data into multiple output luminance gray levels according to a target gamma correction curve, and convert the image data into an output image according to the image data and the multiple output luminance gray levels, and output the output image to the display screen. The first sub-gamma correction curve has a first gamma value, the second sub-gamma correction curve has a second gamma value, and the first gamma value is different from the second gamma value. The first sub-gamma correction curve corresponds to a first luminance gray level range, and the second sub-gamma correction curve corresponds to a second luminance gray level range. The first luminance gray level range and the second luminance gray level range do not overlap, and any luminance gray level in the first luminance gray level range is less than any luminance gray level in the second luminance gray level range.

[0007] Based on the above, the image processing method and the image display device of the present invention can dynamically adjust the gamma correction curve according to the luminance information of the input image data, so as to dynamically adjust the corresponding gamma correction curve according to different luminance information in image data with various luminance information, so as to save power consumption and improve the contrast when displaying the output image. Description of the Drawings

[0008] Figure 1 is a flowchart of an embodiment of the image processing method of the present invention.

[0009] Figure 2 is a combined schematic diagram of the target gamma correction curve of an embodiment of the image processing method of the present invention.

[0010] Figure 3A and Figure 3BIn an embodiment of the image processing method of the present invention, it is a schematic diagram of setting the position of the turning point according to different brightness information.

[0011] Figure 4 It is a block diagram of an embodiment of the image display device of the present invention.

[0012] Figure 5A 、 Figure 5B In an embodiment of the image processing method of the present invention, it is a schematic diagram of calculating brightness information for different image data.

[0013] Figure 6A 、 Figure 6B In an embodiment of the image processing method of the present invention, it is a schematic diagram of setting the turning point according to different brightness information.

[0014] Figure 7A 、 Figure 7B In an embodiment of the image processing method of the present invention, it is a schematic diagram of setting the gamma value according to different brightness information.

[0015] Figure 8A 、 Figure 8B In an embodiment of the image processing method of the present invention, it is a schematic diagram of setting the turning point and the gamma value according to different brightness information.

[0016] Figures 9A - 9C In an embodiment of the image display device of the present invention, it is a comparison of the histograms of the input image data and the brightness gray-scale values of the output image.

[0017] Among them, the reference numerals are explained as follows:

[0018] 400: Image display device

[0019] 401: Display screen

[0020] 402: Controller

[0021] C1: First sub-gamma correction curve

[0022] C1_1~C1_4: Candidate first sub-gamma correction curves

[0023] C2: Second sub-gamma correction curve

[0024] C2_1~C2_4: Candidate second sub-gamma correction curves

[0025] IIM: Image data

[0026] L1, L1’: First average brightness gray-scale value

[0027] L2, L2’: Second average brightness gray-scale value

[0028] Lall, Lall’: Global average luminance gray scale value

[0029] LD, LD’: Luminance level

[0030] S101~S103: Steps

[0031] TC, TC’, TC_sel, TC_sel’, TC_fix, TC_fix’: Target gamma correction curve

[0032] TP, TP’: Turning point

[0033] TP_I, TP_I’: Input luminance gray scale value

[0034] VIM: Output image Detailed implementation manners

[0035] Now, please refer to Figure 1 , Figure 1 , which is a flowchart of an image processing method according to an embodiment of the present invention. The image processing method of the present invention can be used in a display device or a controller for controlling the display device to display an image. In step S101, the display device calculates the luminance information of multiple luminance gray scale values of multiple pixels of the image data. The image data is the image data of the input image to be displayed, and there are multiple pixel data in the image data. The image processing method of the present invention can calculate multiple luminance gray scale values of multiple pixels to obtain the luminance information. The luminance information can be the related information of the luminance gray scale values of multiple pixels in the image data, such as the magnitude of the luminance gray scale value, the distribution histogram of the luminance gray scale value, or various statistical values of multiple luminance gray scale values of multiple pixels, or it can also be the overall luminance state of the image to be displayed of the input image data, such as the information that the image to be displayed is a bright scene or a dark scene.

[0036] In step S102, the display device combines the first gamma sub-correction curve and the second sub-gamma correction curve at the turning point to generate a target gamma correction curve. The first gamma sub-correction curve and the second sub-gamma correction curve have different gamma values. In other words, the gamma correction curve (target gamma correction curve) generated by the image processing method of the present invention is formed by combining two curves with different gamma values. Please refer to the illustration of Figure 2 simultaneously. Figure 2 is a combined schematic diagram of the target gamma correction curve according to an embodiment of the present invention. It should be noted that the first sub-gamma correction curve C1 and the second sub-gamma correction curve C2 can correspond to different gamma values. Therefore, as Figure 2As shown, the curvature performances of the first sub-gamma correction curve C1 and the second sub-gamma correction curve C2 are different. The first sub-gamma correction curve C1 and the second sub-gamma correction curve C2 are combined at the turning point TP to generate the target gamma correction curve TC. In this embodiment, the brightness gray scale value ranges of the target gamma correction curve TC formed by the first sub-gamma correction curve C1 and the second sub-gamma correction curve C2 do not overlap, and in this embodiment, any brightness gray scale value in the brightness gray scale value range of the first sub-gamma correction curve C1 is less than any brightness gray scale value in the brightness gray scale value range of the second sub-gamma correction curve C2.

[0037] In step S103, the display device sets the position of the turning point TP according to the brightness information of the image data calculated in step S101. Refer to Figure 3A 、 Figure 3B for examples, Figure 3A 、 Figure 3B are schematic diagrams of generating a target gamma correction curve for different brightness information in an image processing method according to an embodiment of the present invention. Taking Figure 3A 、Figure Figure 3B as an example, in the embodiment of Figure 3A , the display device sets the position of the turning point TP according to the brightness information of an image data. As Figure 3A shown, the position of the turning point TP corresponds to the input brightness gray scale value TP_I; correspondingly, in the embodiment of Figure 3B , the display device sets the position of the turning point TP' according to the brightness information of another image data. As Figure 3B shown, the position of the turning point TP' corresponds to the input brightness gray scale value TP_I'.

[0038] From the above Figure 1 step S103 and Figure 3A 、 Figure 3B , it can be seen that since Figure 3A 、 Figure 3B determine the positions of the turning points TP and TP' according to different brightness information, the target gamma correction curves TC and TC' are different. Since the turning points TP and TP' are the places where the first sub-gamma correction curve and the second sub-gamma correction curve with different gamma values are combined, the target gamma correction curves TC and TC' have different turning performances. For example, Figure 3A the input brightness gray scale value TP_I corresponding to the position of the turning point TP is a relatively high first value. Therefore, the first brightness gray scale value range corresponding to the first sub-gamma correction curve of the target gamma correction curve TC is larger than the second brightness gray scale value range corresponding to the second sub-gamma correction curve. Since the brightness gray scale values of the larger range part corresponding to the first sub-gamma correction curve on the left side of the turning point TP, such asFigure 3A As shown, in the target gamma correction curve, the output luminance gray level value is suppressed, so the target gamma correction curve TC has a better power saving effect. And in Figure 3A the embodiment, near the turning point TP, since the output luminance gray level value of the target gamma correction curve TC rises steeply with the input luminance gray level value, good contrast is maintained near the turning point TP (the high luminance gray level value area). For another example Figure 3B in the embodiment, the input luminance gray level value TP_I' corresponding to the position of the turning point TP' is a relatively low second value. Since the output luminance gray level value near the turning point TP' as Figure 3B shown rises steeply with the increase of the input luminance gray level value, the target gamma correction curve TC' has better contrast in the darker luminance gray level value area (near the turning point TP').

[0039] It is worth mentioning that since the position of the turning point of the target gamma correction curve in the present invention is determined by the luminance information, the image processing method of the present invention can determine the appropriate turning point position according to the luminance information. For example, if the luminance information indicates that the input image data is a bright scene picture, the image processing method of the present invention can be like Figure 3A shown to set the turning point TP at a high value corresponding to the input luminance gray level value TP_I, so that the target gamma correction curve TC will make the overall display picture have a better power saving effect and maintain good contrast in the high luminance area of the picture. If the luminance information indicates that the input image data is a dark scene picture, the image processing method of the present invention can be like Figure 3B shown to set the turning point TP' at a low value corresponding to the input luminance gray level value TP_I', so that the target gamma correction curve TC' will improve the contrast of the low luminance area of the picture.

[0040] Now please refer to Figure 4 , Figure 4 which is a block diagram of an embodiment of the image display device of the present invention. In the Figure 4 image display device 400, it includes a display screen 401 and a controller 402 coupled to the display screen 401. The display screen 401 is used to display the output image VIM. The controller 402 can receive the input image data IIM through wired or wireless means, and can execute the image processing methods of various embodiments of the present invention, such as Figure 1The steps of S101 to S103 are not described herein again. After the controller 402 executes the image processing method of the present invention to generate the target gamma correction curve, the controller 402 can convert multiple luminance gray scale values of multiple pixels in the input image data IIM into corresponding multiple output luminance gray scale values according to the generated target gamma correction curve. The controller 402 can convert the input image data into the output image VIM according to the color information of multiple pixels in the image data IIM and the output luminance gray scale values. The controller 401 also outputs the output image VIM to the display screen 401 in a wired or wireless manner.

[0041] According to the above Figure 1 image processing method and Figure 4 image display device, the image processing method and image display device of the present invention can generate a corresponding target gamma correction curve according to the luminance information, so as to save power consumption and improve the contrast when displaying the output image based on the luminance information of the input image data.

[0042] In an embodiment of the present invention, the controller 402 can calculate multiple luminance gray scale values of multiple pixels of the image data IIM according to various color space models. For example, in an embodiment of the present invention, when the controller 402 calculates the luminance gray scale value according to the Hue, Saturation, Value (HSV) color space model, it can calculate the Value (V) value as the luminance gray scale value. In another embodiment of the present invention, when the controller 402 calculates the luminance gray scale value according to the Hue, Saturation, Lightness (HSL) color space model, it can calculate the Lightness (L) value as the luminance gray scale value. In another embodiment of the present invention, when the controller 402 calculates the luminance gray scale value according to the Hue, Saturation, Intensity (HSI) color space model, it can calculate the Intensity (I) value as the luminance gray scale value. In another embodiment of the present invention, when the controller 402 calculates the luminance gray scale value according to the YCbCr color space model, it can calculate the Y value representing the Luminance value as the luminance gray scale value. In another embodiment of the present invention, when the controller 402 calculates the luminance gray scale value according to the CIELAB color space model, it can calculate the L* value representing the black and white luminance value as the luminance gray scale value. In the present invention, the calculation of the luminance gray scale value is not limited to the above embodiments, and the chromaticity intensity values of the pixels in the image data can also be calculated according to any color space model to obtain the luminance gray scale value.

[0043] In an embodiment of the present invention, as Figure 2As shown, the first sub-gamma correction curve C1 corresponding to the low input luminance gray scale value has a concave-up curvature performance, and the second sub-gamma correction curve C2 corresponding to the high input luminance gray scale value has a concave-down curvature performance. In this way, near the turning point TP, the target gamma correction curve TC has the characteristic that the output luminance gray scale value rises steeply with the increase of the input luminance gray scale value. That is to say, near the turning point TP, the target gamma correction curve TC will enhance the contrast of the output luminance gray scale value. In an embodiment of the present invention, the gamma value of the first sub-gamma correction curve is greater than 1, and the gamma value of the second sub-gamma correction curve is less than 1.

[0044] In an embodiment of the present invention, as Figure 3A , Figure 3B shown, the input luminance gray scale value TP_I corresponding to the turning point TP will be equal to the output luminance gray scale value corresponding to the turning point TP, and the input luminance gray scale value TP_I' corresponding to the turning point TP' will be equal to the output luminance gray scale value corresponding to the turning point TP'. That is to say, the turning points TP and TP' will be located at the intersection points of the target gamma correction curves TC and TC' and the straight line where the input is equal to the output (such as the slanted dotted line shown in Figure 3A , Figure 3B ). That is to say, near the turning point TP, the target gamma correction curve TC will make the numerical values of the output luminance gray scale value and the input luminance gray scale value close to each other.

[0045] In an embodiment of the present invention, as Figure 3A , Figure 3B shown for the target gamma correction curves TC and TC', at the maximum value of the input luminance gray scale value (such as the ends of TC and TC' shown in the figure), the output luminance gray scale values corresponding to the target gamma correction curves TC and TC' are equal to the input luminance gray scale value. That is to say, the ends of the target gamma correction curves TC and TC' will intersect with the straight line where the input is equal to the output (such as the slanted dotted line shown in Figure 3A , Figure 3B ). In this way, even after the conversion of the target gamma correction curve of the image processing method of the present invention, the maximum luminance gray scale value of the output image will be equal to the maximum luminance gray scale value of the input image data, and the image processing method of the present invention can not change the maximum luminance of the image data.

[0046] Now please refer to Figure 1In step S101, in an embodiment of the present invention, the step S101 of calculating the luminance information of the gray-scale values of the pixels of the image data may include calculating the global average luminance gray-scale value Lall of the luminance gray-scale values, calculating the first average luminance gray-scale value L1 of a plurality of luminance gray-scale values that are less than the global average luminance gray-scale value Lall, calculating a second average luminance gray-scale value L2 of a plurality of luminance gray-scale values that are not less than the global average luminance gray-scale value Lall, and calculating the first average luminance gray-scale value L1 and the second average luminance gray-scale value L2 to obtain a luminance state and a luminance degree, where the luminance state includes a first luminance state and a second luminance state.

[0047] In an embodiment of the present invention, the first luminance state may be a dark scene state of the image frame of the input image data, and the second luminance state may be a bright scene state of the image frame of the image data; the luminance degree may be the degree of being brighter or darker of the image frame of the image data. The microcontroller or the image display device may obtain the luminance state as the first luminance state or the second luminance state and the luminance degree according to the calculation of the first average luminance gray-scale value L1 and the second average luminance gray-scale value L2.

[0048] Now please refer to Figure 5A 、 Figure 5B , Figure 5A 、 Figure 5B are schematic diagrams for calculating luminance information for different image data according to an embodiment of the present invention. Figure 5A is a luminance gray-scale histogram of a bright scene image data, Figure 5B is a luminance gray-scale histogram of a dark scene image data. In Figure 5A the bright scene embodiment, the controller or the image display device may calculate the global average luminance gray-scale value Lall, for example, 216. The controller or the image display device also calculates the average of the luminance gray-scale values on the left side of the global average luminance gray-scale value Lall to obtain the first average luminance gray-scale value L1 of the low luminance gray-scale part, for example, 173, and calculates the average of the luminance gray-scale values on the right side of the global average luminance gray-scale value Lall to obtain the second average luminance gray-scale value L2 of the high luminance gray-scale part, for example, 237. Similarly, in Figure 5B the dark scene embodiment, the controller or the image display device may calculate the global average luminance gray-scale value Lall’, for example, 76, the first average luminance gray-scale value L1’, for example, 37, and the second average luminance gray-scale value L2’, for example, 119. It can be seen from the above embodiments that the controller or the image display device may judge the scene state according to the calculation of the average luminance gray-scale values L1, L1’, and the second average luminance gray-scale values L2, L2’.

[0049] In an embodiment of the present invention, the steps for a controller or an image display device to calculate a first average luminance gray level value and a second average luminance gray level value to obtain the luminance state include: comparing the magnitude of the first average luminance gray level value with a first threshold value and comparing the magnitude of the second average luminance gray level value with a second threshold value to obtain the luminance state. In an embodiment of the present invention, the first threshold value may be a threshold value of the average luminance gray level value of the low-luminance gray level portion. The first threshold value may be, for example, 80. The second threshold value may be a threshold value of the average luminance gray level value of the high-luminance gray level portion. The second threshold value may be, for example, 160. In an embodiment of the present invention, if the first average luminance gray level value is less than the first threshold value and the second average luminance gray level value is less than the second threshold value, a first luminance state of a dark scene state may be obtained for the luminance state; if the first average luminance gray level value is greater than the first threshold value and the second average luminance gray level value is greater than the second threshold value, a second luminance state of a bright scene state may be obtained for the luminance state.

[0050] According to the above embodiment, taking the Figure 5A 、 Figure 5B image data of the scene as an example, in the Figure 5A scene, the first average luminance gray level value L1 is 173, which is greater than the first threshold value of 80, and the second average luminance gray level value L2 is 237, which is also greater than the second threshold value of 160. Therefore, it can be determined that Figure 5A the scene of the image data is a bright scene. Therefore, the controller or the image display device can calculate the first average luminance gray level value L1 and the second average luminance gray level value L2 to determine that the scene is a bright scene, thereby obtaining Figure 5A the luminance state of the image data as the second luminance state. Similarly, in the scene of 5B, the controller or the image display device can calculate the first average luminance gray level value L1' and the second average luminance gray level value L2' to determine that the scene is a dark scene, thereby obtaining Figure 5B the luminance state of the image data as the first luminance state.

[0051] In an embodiment of the present invention, the luminance degree LD can be obtained by calculating the first average luminance gray level value and the second average luminance gray level value. The luminance degree LD is information related to whether the image data is brighter or darker. In a specific embodiment of the present invention, the luminance degree LD = W1×L1 + W2×L2, where L1 is the first average luminance gray level value, L2 is the second average luminance gray level value, and W1 and W2 are the first weight value and the second weight value respectively. The system designer or developer can set the first weight value W1 and the second weight value W2 according to actual requirements or experience to effectively quantify the luminance degree LD.

[0052] In an embodiment of the present invention, Figure 1In step S103, the step of setting the position of the turning point according to the luminance information may further include setting the position of the turning point according to the global average luminance gray level value, the luminance state, and the luminance degree. That is, the controller or the image display device may select the position of the turning point TP of the appropriate target gamma correction curve TC according to the luminance information of the scene. In an embodiment of the present invention, when the luminance state of the image data is the first luminance state, the input luminance gray level value TP_I corresponding to the position of the turning point TC is Lall - LD, where Lall is the global average luminance gray level value and LD is the luminance degree. That is, when the scene of the image data is a dark scene, the position of the turning point TP will shift to a lower luminance gray level value relative to the global average luminance gray level value, and the amount of the shift is determined according to the degree of darkness of the scene. In another embodiment of the present invention, when the luminance state of the image data is the second luminance state, the input luminance gray level value TP_I corresponding to the position of the turning point TC is Lall + LD, where Lall is the global average luminance gray level value and LD is the luminance degree. That is, when the scene of the image data is a bright scene, the position of the turning point TP will shift to a higher luminance gray level value relative to the global average luminance gray level value, and the amount of the shift is determined according to the degree of brightness of the scene.

[0053] The above-described embodiments can be embodied in Figure 6A , Figure 6B in the illustration of Figure 6A , Figure 6B is a schematic diagram of setting turning points according to different luminance information according to an embodiment of the present invention. In Figure 6A the embodiment, the luminance state is the second luminance state, that is, the image data is a bright scene. Under this condition, the input luminance gray level value TP_I corresponding to the turning point TP of the target gamma correction curve TC is the value obtained by adding the global average luminance gray level value Lall to the luminance degree LD. Similarly, in Figure 6B the embodiment, the luminance state is the first luminance state, that is, the image data is a dark scene. Under this condition, the input luminance gray level value TP_I' corresponding to the turning point TP' of the target gamma correction curve TC' is the value obtained by subtracting the luminance degree LD from the global average luminance gray level value Lall'.

[0054] In an embodiment of the present invention, the image processing method and the image display device may further set a first gamma value of the first sub-gamma correction curve and a second gamma value of the second sub-gamma correction curve according to the luminance information. In an embodiment of the present invention, the controller or the image display device may select an appropriate first sub-gamma correction curve from a plurality of candidate first sub-gamma correction curves according to the luminance information. Among them, the plurality of candidate first sub-gamma correction curves all have a curvature performance with an upward notch, and the plurality of first gamma values corresponding to the plurality of candidate first sub-gamma correction curves are greater than 1; the plurality of candidate second sub-gamma correction curves all have a curvature performance with a downward notch, and the plurality of second gamma values corresponding to the plurality of candidate second sub-gamma correction curves are less than 1. Please refer to the following Figure 7A , Figure 7B for an illustration, Figure 7A , Figure 7B which is a schematic diagram of setting gamma values according to different luminance information in an embodiment of the present invention.

[0055] Figure 7A Draw a plurality of candidate first sub-gamma correction curves C1_1 to C1_4, where the plurality of candidate first sub-gamma correction curves C1_1 to C1_4 each have corresponding first gamma values Gamma1_1 to Gamma1_4, and the first gamma values Gamma1_1 to Gamma1_4 are all greater than 1 and Gamma1_4>Gamma1_3>Gamma1_2>Gamma1_1. In an embodiment of the present invention, for example, if there are four different first to fourth image data, where the luminance of the scene of each image data is arranged from the darkest to the brightest as the first image data to the fourth image data. In this embodiment, the controller or the image display device may select the corresponding candidate first sub-gamma correction curves C1_1 to C1_4 according to different luminance information. In this embodiment, the gamma value of the selected first gamma correction curve may be positively correlated with the luminance of the input image data, that is, when the scene is brighter, the controller or the image display device will select a candidate first sub-gamma correction curve with a higher gamma value. For example, when the input image data are the first, second, third, and fourth image data respectively, the corresponding selected candidate first sub-gamma correction curves are the candidate first sub-gamma correction curves C1_1, C1_2, C1_3, and C1_4 respectively. The candidate first sub-gamma correction curves C1_1 to C1_4 of the present invention are only examples, and the number is not limited to 4. That is, in the embodiments of the present invention, there may be multiple candidate first sub-gamma correction curves to more conveniently set the target gamma correction curve for image data with different luminance information.

[0056] Figure 7BMultiple candidate second sub - gamma correction curves C2_1 to C2_4 are plotted. Among them, multiple candidate second sub - gamma correction curves C2_1 to C2_4 each have corresponding second gamma values Gamma2_1 to Gamma2_4. The second gamma values Gamma2_1 to Gamma2_4 are all less than 1 and Gamma2_4 > Gamma1_3 > Gamma1_2 > Gamma2_1. In an embodiment of the present invention, for example, if there are four different first to fourth image data, and the brightness of the scenes of each image data is arranged from the darkest to the brightest as the first image data to the fourth image data. In this embodiment, the controller or the image display device can select the corresponding candidate second sub - gamma correction curves C2_1 to C2_4 according to different brightness information. In this embodiment, the gamma value of the selected second gamma correction curve can be positively correlated with the brightness of the input image data. That is to say, when the scene is brighter, the controller or the image display device will select a candidate first sub - gamma correction curve with a higher gamma value. For example, when the input image data are the first, second, third, and fourth image data respectively, the corresponding selected candidate second sub - gamma correction curves are the candidate second sub - gamma correction curves C2_1, C2_2, C2_3, and C2_4 respectively. The candidate second sub - gamma correction curves C2_1 to C2_4 of the present invention are only examples, and the number is not limited to 4. That is to say, in the embodiments of the present invention, there can be multiple candidate second sub - gamma correction curves to more conveniently set the target gamma correction curve for image data with different brightness information.

[0057] It is worth mentioning that in Figure 7A and Figure 7B In the illustrated embodiment, for the selection methods of the first gamma correction curve and the second gamma correction curve in the target gamma correction curve, under the condition that the image data is a bright scene, as the brightness increases, the first gamma correction curve expands outwards and the second gamma correction curve contracts inwards to achieve a better power - saving effect. And under the condition that the image data is a dark scene, as the brightness decreases, the second gamma correction curve expands outwards, so that the display screen has a better contrast.

[0058] It should be noted that in the embodiments of the present invention, the display screen brightness of the input image data can be obtained according to the brightness state and the brightness degree. In the first brightness state where the display screen is a dark scene, the darker the scene of the display screen, the higher the brightness degree; in the second brightness state where the display screen is a bright scene, the brighter the scene of the display screen, the higher the brightness degree. Therefore, in the present invention, the controller and the image display device can determine the selected candidate first gamma correction curve and candidate second gamma correction curve according to the brightness state and the brightness degree. For example, when the brightness state is the first brightness state, both the first gamma value and the second gamma value are negatively correlated with the brightness degree; when the brightness state is the second brightness state, both the first gamma value and the second gamma value are positively correlated with the brightness degree.

[0059] In an embodiment of the present invention, it can be combined with Figure 6A 、 Figure 6B the setting method of the turning point TP, and Figure 7A 、 Figure 7B the selection methods of the first gamma correction curve and the second gamma correction curve of Figure 8A 、 Figure 8B to set the target gamma correction curve. Now, please refer to Figure 8A 、 Figure 8B which are schematic diagrams for setting the turning point, the first gamma correction curve, and the second gamma correction curve according to different brightness information in accordance with this embodiment.

[0060] In Figure 8A 's embodiment, the display screen of the input image data is a dark scene. In this embodiment, the position of the input brightness gray level value TP_I corresponding to the turning point TP can be determined according to the global average brightness gray level value Lall, the brightness state, and the brightness degree LD. For example, in Figure 8A the input image data, the brightness state is the first brightness state. Therefore, the input brightness gray level value TP_I corresponding to the turning point TP is located at the global average brightness gray level value Lall minus the brightness degree LD. In an embodiment of the present invention, after determining the position of the turning point TP, if the gamma values of the first gamma correction curve and the second gamma correction curve are preset fixed values, the target gamma correction curve can be, for example, Figure 8A the target gamma correction curve TC_fix shown by the dotted curve in Figure 7A 、 Figure 7B In another embodiment of the present invention, after determining the position of the turning point TP, if the first gamma correction curve and the second gamma correction curve are selected according to the embodiments of Figure 8A the controller and the display device can select the first gamma correction curve and the second gamma correction curve with smaller gamma values according to the first brightness state and the brightness degree LD, and obtain Figure 8A the target gamma correction curve TC_sel shown by the solid curve inFigure 8A As shown, the target gamma correction curve TC_sel will be more extended to the right of the turning point TP compared to the target gamma correction curve TC_fix. Therefore, if the first gamma correction curve and the second gamma correction curve are selected according to the embodiments of Figure 7A and Figure 7B , the target gamma correction curve TC_sel will further improve the contrast of the output image.

[0061] In Figure 8B 's embodiment, the display screen of the input image data is a bright scene. In this embodiment, the position of the input luminance gray level value TP_I' corresponding to the turning point TP' can be determined according to the global average luminance gray level value Lall', the luminance state, and the luminance degree LD'. For example, in Figure 8B 's input image data, the luminance state is the second luminance state. Therefore, the input luminance gray level value TP_I' corresponding to the turning point TP' is located at the global average luminance gray level value Lall' plus the luminance degree LD'. In an embodiment of the present invention, after determining the position of the turning point TP, if the gamma values of the first gamma correction curve and the second gamma correction curve are preset fixed values, the target gamma correction curve can be, for example, Figure 8B the target gamma correction curve TC_fix' shown by the dashed curve in Figure 7A and Figure 7B 's embodiment, after determining the position of the turning point TP, if the first gamma correction curve and the second gamma correction curve are selected according to the embodiments of Figure 8B , the controller and the display device can select the first gamma correction curve and the second gamma correction curve with larger gamma values according to the second luminance state and the luminance degree LD', and obtain Figure 8B the target gamma correction curve TC_sel' shown by the solid curve in Figure 7A and Figure 7B 's embodiment. As shown in

[0062] Please refer to Figures 9A - 9C and Figures 9A - 9C is a comparison of the luminance gray level histograms of the output image and the input image data generated by the image display device according to the present invention. Among them, in Figure 9A and Figure 9B , the display screen of the input image data is a bright scene. In Figure 9CAmong them, the display screen of the input image data is a dark scene. In Figures 9A - 9C Among them, the solid contour is a schematic diagram of the luminance gray scale histogram of the input image data, and the graph filled with oblique lines is a schematic diagram of the luminance gray scale histogram of the output image. As Figure 9A , Figure 9B shown, the luminance gray scale histogram of the output image moves more towards the lower luminance gray scale value relative to the luminance gray scale histogram of the input image data. Therefore, in Figure 9A , Figure 9B cases, the image processing method and the image display device of the present invention can reduce the power consumption of the output image. As Figure 9C shown, the luminance gray scale histogram of the output image moves more towards the higher luminance gray scale value relative to the luminance gray scale histogram of the input image data. Therefore, the distribution of the luminance gray scale values of the output image is more uniform. Therefore, in Figure 9C cases, the image processing method and the image display device of the present invention can improve the contrast of the output image.

[0063] In summary, the image processing method and the image display device of the present invention can generate a corresponding target gamma correction curve according to the luminance information, so as to save power consumption and improve the contrast when displaying the output image based on the luminance information of the input image data. More specifically, the image processing method and the image display device of the present invention can reduce the overall brightness of the output image without changing the maximum brightness to achieve the power-saving effect when the input image data is a bright scene with a relatively bright light, and can improve the contrast of the display screen of the output image when the input image data is a dark scene with a relatively dark light.

Claims

1. An image processing method, comprising: Calculate the luminance information of multiple luminance gray levels of multiple pixels of an image data; Combine a first sub-gamma correction curve and a second sub-gamma correction curve at a turning point to generate a target gamma correction curve, where a first gamma value of the first sub-gamma correction curve and a second gamma value of the second sub-gamma correction curve are different; and Set the position of the turning point according to the luminance information, where the first sub-gamma correction curve corresponds to a first luminance gray level range, the second sub-gamma correction curve corresponds to a second luminance gray level range, the first luminance gray level range and the second luminance gray level range do not overlap, and any luminance gray level value in the first luminance gray level range is less than any luminance gray level value in the second luminance gray level range, where the step of calculating the luminance information of the luminance gray levels of the pixels of the image data includes: Calculate a global average luminance gray level value of the luminance gray levels; Calculate a first average luminance gray level value of the luminance gray levels less than the global average luminance gray level value; Calculate a second average luminance gray level value of the luminance gray levels not less than the global average luminance gray level value; and Calculate the first average luminance gray level value and the second average luminance gray level value to obtain a luminance state and a luminance degree, where the luminance state includes a first luminance state and a second luminance state.

2. The image processing method according to claim 1, wherein the step of calculating the first average luminance gray scale value and the second average luminance gray scale value to obtain the luminance state and the luminance degree further comprises: Compare the size of the first average luminance gray level value with a first threshold and compare the size of the second average luminance gray level value with a second threshold to obtain the luminance state, where, When the first average luminance gray level value is less than the first threshold and the second average luminance gray level value is less than the second threshold, obtain that the luminance state is the first luminance state; When the first average luminance gray level value is greater than the first threshold and the second average luminance gray level value is greater than the second threshold, obtain that the luminance state is the second luminance state.

3. The image processing method according to claim 1, wherein the luminance degree LD = W1 × L1 + W2 × L2, wherein L1 is the first average luminance gray scale value, L2 is the second average luminance gray scale value, and W1 and W2 are a first weight value and a second weight value respectively.

4. The image processing method according to claim 1, wherein the step of setting the position of the turning point according to the luminance information comprises: Set the position of the turning point according to the global average luminance gray level value, the luminance state and the luminance degree, where, When the luminance state is the first luminance state, an input luminance gray level value TP_I corresponding to the position of the turning point = Lall - LD; When the luminance state is the second luminance state, the input luminance gray level value TP_I corresponding to the position of the turning point = Lall + LD, where Lall is the global average luminance gray level value and LD is the luminance degree.

5. The image processing method according to claim 1, wherein the image processing method further comprises: Set the first gamma value and the second gamma value according to the luminance information, where the first gamma value is greater than 1 and the second gamma value is less than 1.

6. The image processing method according to claim 5, wherein the step of setting the first gamma value and the second gamma value according to the luminance information comprises: Set the first gamma value and the second gamma value according to the luminance state and the luminance degree, where When the luminance state is the first luminance state, the first gamma value is negatively correlated with the luminance degree and the second gamma value is negatively correlated with the luminance degree, When the luminance state is the second luminance state, the first gamma value is positively correlated with the luminance degree and the second gamma value is positively correlated with the luminance degree.

7. The image processing method according to claim 1, wherein the first gamma value is greater than 1 and the second gamma value is less than 1.

8. The image processing method according to claim 1, wherein an input luminance gray level value corresponding to the position of the turning point is equal to an output luminance gray level value corresponding to the position of the turning point.

9. The image processing method according to claim 1, wherein based on the target gamma correction curve, a maximum input luminance gray level value is equal to a maximum output luminance gray level value.

10. An image display device, comprising: A display screen for displaying an output image; And A controller coupled to the display screen and configured to: Receive an image data, and calculate a luminance information of a plurality of luminance gray levels of the plurality of pixels of the image data; Cause a first sub-gamma correction curve and a second sub-gamma correction curve to be combined with each other at a turning point to generate a target gamma correction curve, wherein a first gamma value of the first sub-gamma correction curve and a second gamma value of the second sub-gamma correction curve are different; Set the position of the turning point according to the luminance information; Convert the luminance gray levels of the image data into a plurality of output luminance gray levels according to the target gamma correction curve; And Convert the image data into the output image according to the image data and the output luminance gray levels, and output the output image to the display screen, wherein the first sub-gamma correction curve corresponds to a first luminance gray level range, the second sub-gamma correction curve corresponds to a second luminance gray level range, the first luminance gray level range and the second luminance gray level range do not overlap, and any luminance gray level in the first luminance gray level range is less than any luminance gray level in the second luminance gray level range, wherein the controller is configured to: Calculate a global average luminance gray level of the luminance gray levels; Calculate a first average luminance gray level of a plurality of luminance gray levels less than the global average luminance gray level among the luminance gray levels; Calculate a second average luminance gray level of a plurality of luminance gray levels not less than the global average luminance gray level among the luminance gray levels; And Calculate the first average luminance gray level and the second average luminance gray level to obtain a luminance state and a luminance degree, wherein the luminance state includes a first luminance state and a second luminance state.

11. The image display device according to claim 10, wherein the controller is configured to: compare the first average luminance gray level value with a first threshold value and compare the second average luminance gray level value with a second threshold value to obtain the luminance state, wherein, When the first average luminance gray level is less than the first threshold and the second average luminance gray level is less than the second threshold, obtain the luminance state as the first luminance state; When the first average luminance gray level is greater than the first threshold and the second average luminance gray level is greater than the second threshold, obtain the luminance state as the second luminance state.

12. The image display device according to claim 10, wherein the luminance degree LD = W1 × L1 + W2 × L2, wherein L1 is the first average luminance gray level value, L2 is the second average luminance gray level value, and W1 and W2 are a first weight value and a second weight value, respectively.

13. The image display device according to claim 10, wherein the controller is configured to: set the position of the turning point according to the global average luminance gray level value, the luminance state, and the luminance degree, wherein, When the luminance state is the first luminance state, an input luminance gray level TP_I corresponding to the position of the turning point = Lall - LD; When the luminance state is the second luminance state, the input luminance gray level TP_I corresponding to the position of the turning point = Lall + LD, wherein Lall is the global average luminance gray level and LD is the luminance degree.

14. The image display device according to claim 10, wherein the controller is configured to: Set the first gamma value and the second gamma value according to the luminance information, wherein the first gamma value is greater than 1 and the second gamma value is less than 1.

15. The image display device according to claim 14, wherein the controller is configured to: Set the first gamma value and the second gamma value according to the luminance state and the luminance level, wherein, When the luminance state is the first luminance state, the first gamma value is negatively correlated with the luminance degree and the second gamma value is negatively correlated with the luminance degree, When the luminance state is the second luminance state, the first gamma value is positively correlated with the luminance degree and the second gamma value is positively correlated with the luminance degree.

16. The image display device according to claim 10, wherein the first gamma value is greater than 1 and the second gamma value is less than 1.

17. The image display device according to claim 10, wherein an input luminance gray scale value corresponding to the position of the turning point is equal to an output luminance gray scale value corresponding to the position of the turning point.

18. The image display device according to claim 10, wherein based on the target gamma correction curve, a maximum input luminance gray scale value is equal to a maximum output luminance gray scale value.

Images