CN118645065A - Display screen brightness adjustment method and device, storage medium, terminal, and computer program product - Google Patents

Abstract

A method and device for adjusting the brightness of a display screen, a storage medium, a terminal, and a computer program product, the method comprising: obtaining an image block to be processed, and determining a block brightness value of each image block; determining a target brightness gain corresponding to each preset brightness threshold of the image block at least based on the block brightness value of the image block; performing function fitting using each brightness threshold of the image block and its corresponding target brightness gain to obtain a brightness-gain mapping function; for each target pixel to be adjusted in the image block, determining a target brightness gain corresponding to the target pixel according to the brightness-gain mapping function, and performing brightness adjustment on the brightness value of the target pixel using the target brightness gain to determine a processed image block; performing block splicing on each processed image block to obtain an adjusted display screen. The above scheme can reduce the power consumption of the display while ensuring the screen display effect.

Description

Display screen brightness adjustment method and device, storage medium, terminal, computer program product

Technical Field

The present invention relates to the field of display technology, and in particular to a method and device for adjusting the brightness of a display screen, a storage medium, a terminal, and a computer program product.

Background Art

At present, most high-end electronic devices use display technology based on organic light-emitting diodes (OLED). Compared with traditional liquid crystal display (LCD) technology, OLED has the advantages of high brightness, high contrast, and bright colors. At present, high-end electronic devices are gradually transitioning from traditional LCD display to OLED display. However, due to the high brightness of OLED display characteristics, its display power consumption is significantly higher than LCD in some scenarios. And because the display principles of LCD and OLED are different, the related display algorithms previously applicable to LCD display cannot be directly applied to OLED display. For example, the CABC algorithm used to reduce display power consumption on LCD. How to reduce the display power consumption and extend the use time of electronic devices without significantly reducing the display effect is an important application direction.

In the prior art, an automatic current limiting method for an OLED driving device is provided to reduce the display power consumption of the OLED. The method obtains the original image currently displayed and calculates the average brightness of the image; according to different average brightness, a lower limit of the brightness gain is set (i.e., the frame peak brightness ratio, which is less than 1); then the internal difference of each pixel in the image is calculated (i.e., the difference between the largest sub-pixel and the smallest sub-pixel in the three RGB sub-pixels); the larger the pixel internal difference, the greater the brightness reduction of the pixel; a mapping relationship is established based on the pixel internal difference and the brightness gain. Therefore, for each pixel, by calculating its internal difference, the corresponding brightness gain can be found, and then the current brightness value of the pixel is multiplied by the brightness gain to obtain the brightness value processed by the algorithm.

The disadvantages of the above scheme are mainly in the following aspects: (1) The lower limit of the brightness gain is set by the average brightness of the entire image. First of all, it is difficult to reflect the brightness of different blocks of the entire image only by the average brightness of the entire image. For example, for an image with a large contrast, its average brightness is large, so its brightness decreases greatly according to the setting. However, for low-grayscale pixels, excessive reduction in their brightness has a significant negative impact on the visual effect. Moreover, the brightness of different areas of an image is not consistent, and the average brightness of the entire image is not indicative; (2) After calculating the brightness gain, this method needs to multiply the RGB sub-pixel of each pixel by the gain value to adjust the grayscale. This greatly increases the amount of calculation and complexity of the algorithm, and reduces the algorithm processing efficiency and real-time performance.

Summary of the invention

The technical problem solved by the embodiment of the present invention is how to reduce the power consumption of display while ensuring the picture display effect.

To solve the above technical problems, an embodiment of the present invention provides a method for adjusting the brightness of a display screen, comprising the following steps: obtaining an image block to be processed, and determining a block brightness value of each image block, wherein the image block is obtained by dividing the display screen to be adjusted into blocks; determining a target brightness gain corresponding to each preset brightness threshold of the image block based at least on the block brightness value of the image block, wherein each image block has a plurality of preset different brightness thresholds, and the larger the brightness threshold, the smaller the corresponding target brightness gain; performing function fitting using each brightness threshold of the image block and its corresponding target brightness gain to obtain a brightness-gain mapping function of the image block; determining, for each target pixel to be adjusted in the image block, a target brightness gain corresponding to the target pixel according to the brightness-gain mapping function, and performing brightness adjustment on the brightness value of the target pixel using the target brightness gain to determine a processed image block; and performing block splicing on each processed image block to obtain an adjusted display screen.

Optionally, at least based on the block brightness value of the image block, determining the target brightness gain corresponding to each preset brightness threshold of the image block, including: searching for the brightness gain corresponding to the block brightness value of the image block from a preset brightness interval-brightness gain mapping relationship table, recorded as the brightness gain lower limit value, wherein the brightness interval-brightness gain mapping relationship table includes a one-to-one correspondence between multiple pre-divided brightness intervals and multiple preset brightness gains; between the brightness gain lower limit value and the preset brightness gain upper limit value, determining multiple target brightness gains including the brightness gain lower limit value, and corresponding the multiple target brightness gains to multiple different brightness thresholds of the image block one by one; wherein, after sorting the multiple target brightness gains, the difference between every two target brightness gains with adjacent numerical values falls within the preset brightness difference interval.

Optionally, each brightness threshold value of the image block and its corresponding target brightness gain are used to perform function fitting to obtain a brightness-gain mapping function of the image block, including: selecting at least one target brightness threshold value from each brightness threshold value of the image block; using each target brightness threshold value and its corresponding target brightness gain as the horizontal coordinate and vertical coordinate of a single segmentation point, respectively, to obtain at least one segmentation point; using each brightness threshold value of the image block and its corresponding target brightness gain as the horizontal coordinate and vertical coordinate of a fitting point, respectively, and using multiple preset target functions and each segmentation point to perform piecewise function fitting to obtain the brightness-gain mapping function.

Optionally, the multiple preset objective functions are selected from: a constant function, a linear function, and a power function.

Optionally, the multiple preset objective functions include at least two types of objective functions; wherein the first objective function in the brightness-gain mapping function is a constant function, and the remaining objective functions are all power functions.

Optionally, the target pixel to be adjusted is a pixel located in the edge area of the image block; the target brightness gain corresponding to the target pixel is determined according to the brightness-gain mapping function, including: for each pixel in a preset sub-area around the target pixel, the brightness value of each pixel is substituted into the brightness gain mapping function of the image block to which it belongs, so as to obtain the target brightness gain corresponding to each pixel, wherein the preset sub-area includes pixels of at least one image block adjacent to the position of the image block to which the target pixel belongs; and the weighted average of the target brightness gains corresponding to all pixels in the preset sub-area is used as the target brightness gain corresponding to the target pixel.

Optionally, before performing block stitching on each processed image block, the method further includes: for each target pixel located in the edge area of the processed image block, updating the adjusted brightness value of the target pixel by taking the weighted average of the adjusted brightness values of each pixel in a preset sub-area around the target pixel; wherein the preset sub-area includes pixels of at least one image block adjacent to the position of the image block to which the target pixel belongs.

Optionally, the brightness-gain mapping function is a piecewise function including a plurality of objective functions, each objective function having a corresponding brightness threshold interval and a corresponding preset brightness deviation, and each two adjacent objective functions are connected by a segmentation point; the brightness adjustment of the brightness value of the target pixel using the target brightness gain includes: determining the brightness threshold interval into which the brightness value of the target pixel falls, and obtaining a preset brightness deviation corresponding to the objective function to which the brightness threshold interval belongs, recorded as a target brightness deviation; calculating the product of the target brightness gain and the brightness value of the target pixel, and then taking the sum of the product and the target brightness deviation as the adjusted brightness value of the target pixel.

Optionally, after obtaining the adjusted display picture, the method further includes: for each processed image block of the adjusted display picture, determining whether the difference between the block brightness value of the processed image block at the same position of the adjacent previous frame adjusted display picture and that of the processed image block is greater than a preset brightness difference; if the judgment result is yes, determining, for each target pixel of the processed image block, the target pixel at the same position in the adjacent previous frame adjusted display picture; and performing a secondary adjustment on the adjusted brightness value of the target pixel of the processed image block by using the average value of the target brightness gain corresponding to the target pixel and the target brightness gain corresponding to the target pixel at the same position, thereby obtaining a secondary adjusted display picture.

Optionally, the pixels to be adjusted in the image block are selected from the remaining pixels except the pixels whose chromaticity values fall within the target chromaticity interval.

Optionally, the block brightness value of the image block is selected from any one of the following: an average brightness value of each pixel of the image block, a maximum brightness value of each pixel of the image block, and a minimum brightness value of each pixel of the image block.

The embodiment of the present invention further provides a brightness adjustment device for a display screen, comprising: an image block acquisition module, used to acquire an image block to be processed, and determine a block brightness value of each image block, wherein the image block is obtained by dividing the display screen to be adjusted into blocks; a corresponding relationship determination module, used to determine, based at least on the block brightness value of the image block, a target brightness gain corresponding to each preset brightness threshold of the image block, wherein each image block has a plurality of preset different brightness thresholds, and the larger the brightness threshold, the smaller the corresponding target brightness gain; a function fitting module, used to perform function fitting using each brightness threshold of the image block and its corresponding target brightness gain, to obtain a brightness-gain mapping function of the image block; an image block brightness adjustment module, used to determine, for each target pixel to be adjusted in the image block, a target brightness gain corresponding to the target pixel according to the brightness-gain mapping function, and perform brightness adjustment on the brightness value of the target pixel using the target brightness gain, to determine a processed image block; and an image block splicing module, used to perform block splicing on each processed image block, to obtain an adjusted display screen.

An embodiment of the present invention further provides a storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned method for adjusting the brightness of a display screen are executed.

An embodiment of the present invention further provides a terminal, including a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and the processor executes the steps of the above-mentioned display screen brightness adjustment method when running the computer program.

An embodiment of the present invention further provides a computer program product, including a computer program, and when the computer program is executed by a processor, the steps of the above-mentioned method for adjusting the brightness of a display screen are performed.

Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

Compared with the prior art that determines the global average brightness with the whole image (or display screen) as the granularity, and determines the lower limit of the brightness gain and the pixel internal difference-brightness gain mapping relationship based on the global average brightness, in the embodiment of the present invention, by dividing the display screen to be adjusted into a number of independent image blocks, the mapping function between brightness and brightness gain is determined with the image block as the granularity, so as to adjust the brightness of the pixels of each block respectively, a better and more refined brightness adjustment effect can be obtained, and the power consumption of the display can be reduced while improving the picture display effect. Furthermore, in the embodiment of the present invention, the determination of the mapping relationship does not need to calculate the pixel internal difference of each pixel, but directly uses a plurality of different brightness thresholds preset for each block and the brightness gain for mapping, which can significantly reduce the amount of calculation and the complexity of calculation, and improve the efficiency and real-time performance of brightness adjustment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flow chart of a method for adjusting brightness of a display screen according to an embodiment of the present invention;

FIG2 is a flow chart of a specific implementation of step S12 in FIG1 ;

FIG3 is a flow chart of a specific implementation of step S13 in FIG1 ;

FIG4 is a schematic diagram of a curve of a brightness-gain mapping function according to an embodiment of the present invention;

FIG5 is a flow chart of a specific implementation of step S14 in FIG1 ;

6 is a schematic diagram of a mapping curve between a brightness value before adjustment and a brightness value after adjustment according to an embodiment of the present invention;

7 is a partial flow chart of another method for adjusting the brightness of a display screen according to an embodiment of the present invention;

FIG. 8 is a schematic structural diagram of a device for adjusting brightness of a display screen according to an embodiment of the present invention.

DETAILED DESCRIPTION

In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

Referring to FIG. 1 , FIG. 1 is a flow chart of a method for adjusting the brightness of a display screen in an embodiment of the present invention. The method can be applied to a terminal or electronic device with an image processing function, for example, selected from but not limited to computers, mobile phones, tablet computers, televisions, smart wearable devices (such as smart watches), vehicle-mounted terminals, etc. The terminal can be a terminal based on display technologies such as organic light-emitting diodes (OLED), mini light-emitting diodes (mini-LED), and micro light-emitting diodes (micro-LED).

The method may include steps S11 to S15:

Step S11: obtaining image blocks to be processed, and determining a block brightness value of each image block, wherein the image blocks are obtained by dividing the display image to be adjusted into blocks;

Step S12: determining a target brightness gain corresponding to each preset brightness threshold of the image block based at least on the block brightness value of the image block, wherein each image block has a plurality of preset different brightness thresholds, and a larger brightness threshold has a smaller corresponding target brightness gain;

Step S13: performing function fitting using each brightness threshold of the image block and its corresponding target brightness gain to obtain a brightness-gain mapping function of the image block;

Step S14: for each target pixel to be adjusted in the image block, determine the target brightness gain corresponding to the target pixel according to the brightness-gain mapping function, and use the target brightness gain to perform brightness adjustment on the brightness value of the target pixel to determine the processed image block;

Step S15: performing block splicing on each processed image block to obtain an adjusted display image.

In the specific implementation of step S11, the display screen to be adjusted may be a picture frame or an image frame displayed on the display screen of the terminal at a certain moment. There may be many ways to obtain the display screen to be adjusted, which is not limited in the embodiment of the present invention. For example, the data in the frame buffer (Frame Buffer) may be read through a screenshot thread, and the data may be saved as a screen shot, which is the display screen to be adjusted. Since the frame buffer provides an interface to abstract the display device as a frame buffer, the screen may be displayed on the display screen of the terminal by writing the synthesized screen frame into the frame buffer. By reading the data in the Frame Buffer (the data mainly includes the channel information of each pixel in the screen, such as the information of the R channel, the G channel, and the B channel), it is possible to screenshot the current display screen of the display screen.

It is understandable that the brightness information, color information, etc. of different areas of a frame are often different. If only the average brightness information or average color information of the entire picture is calculated, it is difficult to accurately reflect the specific conditions of different positions of the picture, and therefore it is difficult to accurately and reasonably adjust the brightness of different positions. To solve the aforementioned problems, after obtaining the display picture to be adjusted, the present application performs block processing on the display picture, for example, by dividing the entire picture into X image blocks (X is a positive integer), and treating each image block as a separate small image, and performing independent algorithm processing. The embodiment of the present invention does not limit the number and shape of the divided image blocks, and can be appropriately set according to the needs of the actual application scenario. Generally, the more the number of divided image blocks, the better the effect of picture brightness adjustment, but at the same time, the greater the hardware overhead.

Specifically, the block brightness value of the image block is selected from any one of the following: an average brightness value of each pixel of the image block, a maximum brightness value of each pixel of the image block, and a minimum brightness value of each pixel of the image block.

In a specific implementation, if the format of the display image to be adjusted is RGB format, its brightness and chromaticity information are mixed together, and the image in RGB format needs to be converted into HSV format or YUV format, where, for HSV format images, H represents hue, S represents saturation, and V represents brightness (i.e., brightness Value); for YUV format images, Y represents luminance (Luminance or Luma), that is, grayscale value, and U and V represent chromaticity (Chrominance or Chroma, used to describe image color and saturation). Through format conversion, chromaticity and brightness information can be separated.

In a specific implementation, for each image block, a histogram statistical method can be used to count the brightness values of each pixel in the image block to obtain a brightness statistical histogram, from which the number of pixels falling into each brightness statistical interval can be known. Based on the brightness statistical histogram, the average brightness value and/or the maximum brightness value and/or the minimum brightness value of each pixel in the corresponding image block can be conveniently and quickly calculated. The embodiment of the present invention does not limit the number and division method of the brightness statistical interval (bin), but in order to ensure that the calculated block brightness value information is sufficiently accurate, the number of Bins should not be too small.

In the specific implementation of step S12, the preset multiple different brightness thresholds of each image block can be determined in the following manner: determine the brightness extreme value according to the bit width of the image block, divide N+1 brightness threshold intervals in the interval from 0 to the brightness extreme value, and then the N division points are used as the multiple different brightness thresholds corresponding to the image block. For example, if the bit width of the image block is 8 bits, the brightness extreme value is 2 ⁸ -1=255, and [0,255] is divided into N+1 brightness threshold intervals: [0, thr ₁ ], (thr ₁ , thr ₂ ], (thr ₂ , thr ₃ ] ... (thr _n , 255], then the N brightness thresholds corresponding to the image block are: thr ₁ , thr ₂ , thr ₃ ... thr _n .

Among them, the division method of N+1 brightness threshold intervals can be average division or non-average division. In other words, the difference between the maximum brightness and the minimum brightness of each brightness threshold interval can be the same or different. It can be understood that the more the number of brightness threshold interval divisions, the more the number of brightness thresholds, the more data for subsequent function fitting, and the higher the fitting accuracy. However, the number of brightness threshold intervals should not be too many, otherwise it will increase the computational overhead.

In this application, the value range of the target brightness gain is not particularly limited. It should be noted that if the target brightness gain ranges between 0 and 1, the brightness will decrease after the original brightness value of the pixel is multiplied by the target brightness gain. If the target brightness gain is greater than 1, the brightness will increase after the original brightness value of the pixel is multiplied by the target brightness gain. In the process of determining the target brightness gain corresponding to each brightness threshold, it is necessary to set the corresponding target brightness gain for different brightness thresholds in combination with the picture display effect and the power consumption requirement of the display.

Referring to Fig. 2, Fig. 2 is a flowchart of a specific implementation of step S12 in Fig. 1. In this implementation, step S12 may include steps S121 to S122.

In step S121, the brightness gain corresponding to the block brightness value of the image block is searched from a preset brightness interval-brightness gain mapping relationship table and recorded as the brightness gain lower limit value, wherein the brightness interval-brightness gain mapping relationship table includes a one-to-one correspondence between multiple pre-divided brightness intervals and multiple preset brightness gains.

In step S122, a plurality of target brightness gains including the brightness gain lower limit value are determined between the brightness gain lower limit value and a preset brightness gain upper limit value, and the plurality of target brightness gains are matched one-to-one with a plurality of different brightness thresholds of the image block.

After the plurality of target brightness gains are sorted, the difference between every two target brightness gains with adjacent numerical values falls within a preset brightness difference interval.

In a specific implementation, the plurality of pre-divided brightness intervals may also be a plurality of brightness intervals obtained by dividing the interval from 0 to the brightness extreme value, and the method for determining the brightness extreme value is described above and will not be repeated here. The brightness interval division method may be an average division or an uneven division.

The following example illustrates a method for determining the target brightness gain corresponding to each brightness threshold of an image block. Table 1 below shows a brightness interval-brightness gain mapping relationship table (the data in Table 1 are only used for illustration and do not constitute a limitation on the actual values). For example, when the block brightness value (e.g., average brightness value) of the image block is in the brightness interval of 240-255, the corresponding brightness gain lower limit value gain(n)=0.62; when the block brightness value of the image block is in the brightness interval of 220-240, the corresponding brightness gain lower limit value gain(n)=0.66.

After determining the brightness gain lower limit value, a plurality of target brightness gains (recorded as: gain(n), gain(n-1)..., gain(3), gain(2), gain(1)) including the brightness gain lower limit value are determined between the brightness gain lower limit value and the preset brightness gain upper limit value, and the plurality of target brightness gains are corresponded one by one to a plurality of different brightness thresholds of the image block, wherein the larger the brightness threshold value, the smaller the corresponding target brightness gain (i.e., the brightness threshold value and the target brightness gain are negatively correlated); wherein, after sorting the plurality of target brightness gains, the difference between each two target brightness gains having adjacent numerical values falls within a preset brightness difference interval.

As a non-limiting embodiment, the preset upper limit value of the brightness gain is 1, then each target brightness gain satisfies: 0＜gain(n)≤gain(n-1)……≤gain(2)≤gain(1)≤1, and the difference between every two adjacent target brightness gains gain(n-1)-gain(n) falls within the preset brightness difference range.

Table 1 Brightness range-brightness gain mapping relationship table

It can be understood that, based on the negative correlation between the brightness threshold and the target brightness gain, compared with randomly determining the target brightness gain corresponding to each brightness threshold, or randomly determining multiple target brightness gains with numerical order between the brightness gain lower limit and the preset brightness gain upper limit, this embodiment sets a brightness difference interval, and limits the difference between each two target brightness gains with adjacent numerical values after sorting to fall into the brightness difference interval. In this way, it can be avoided that the numerical difference between each two target brightness gains with adjacent numerical values is too large, resulting in a reduction in the balance of the display screen brightness adjustment and affecting the screen display effect.

In the specific implementation of step S13, each brightness threshold value of the image block and its corresponding target brightness gain are used to perform function fitting to obtain a brightness-gain mapping function of the image block.

In a first specific implementation, a single objective function may be used to perform whole-segment function fitting to obtain the brightness-gain mapping function of the image block. The whole-segment function may be selected from any one of a constant function, a linear function, and the like.

In a second specific implementation, a single objective function may be used to perform piecewise function fitting to obtain the brightness-gain mapping function of the image block, that is, each piecewise function of the brightness-gain mapping function is an objective function of the same type. The single objective function may be selected from, for example, any one of a constant function and a linear function.

In a third specific implementation, multiple preset objective functions can be used to perform piecewise function fitting to obtain the brightness-gain mapping function of the image block; wherein the multiple preset objective functions include at least two types of objective functions, for example, at least two functions selected from a constant function, a linear function, a power function, etc.

The method of obtaining the brightness-gain mapping function by performing piecewise function fitting is described in detail below in conjunction with FIG. 3 .

Referring to Fig. 3, Fig. 3 is a flowchart of a specific implementation of step S13 in Fig. 1. In this implementation, step S13 may include steps S131 to S133.

In step S131 , at least one target brightness threshold is selected from each brightness threshold of the image block.

In step S132, each target brightness threshold and the corresponding target brightness gain are used as the abscissa and ordinate of a single segmentation point, respectively, to obtain at least one segmentation point.

It can be understood that the more target brightness thresholds are selected, the more segmentation points of the brightness-gain mapping function are, and the higher the precision of the subsequent brightness gain mapping and brightness adjustment using the brightness-gain mapping function.

In step S133, each brightness threshold value of the image block and its corresponding target brightness gain are used as the horizontal coordinate and the vertical coordinate of the fitting point respectively, and a plurality of preset target functions and each segmentation point are used to perform piecewise function fitting to obtain the brightness-gain mapping function.

The plurality of preset objective functions may be selected from, but not limited to, a constant function, a linear function, and a power function.

Specifically, the plurality of preset objective functions include at least two types of objective functions, wherein the first objective function in the brightness-gain mapping function is a constant function, and the remaining objective functions are all power functions. The first objective function is an objective function corresponding to a brightness value within a range from 0 to a minimum target brightness threshold.

Specifically, the brightness-gain mapping function can be expressed by the following formula:

Wherein, Gain represents the brightness-gain mapping function, V represents the independent variable of the power function, i.e., the brightness value of the pixel (specifically, the original brightness value of the pixel or the brightness value before adjustment), a ₁ to a _n represent the first coefficients of the power functions of the 1st to nth segments, b ₁ to b _n represent the second coefficients of the power functions of the 1st to nth segments, c ₁ to c _n represent the third coefficients of the power functions of the 1st to nth segments, k ₁ to k _n are preset constants for representing the powers of the power functions of the 1st to nth segments, gain ₀ represents a brightness gain constant, and thr ₁ ′ to thr _n ′ represent the 1st to nth target brightness thresholds. As a non-limiting example, the brightness gain constant gain ₀ may be the target brightness gain gain(1) corresponding to the minimum brightness threshold of the image block.

Wherein, k ₁ ～k _n may be the same or different. As a non-limiting example, k ₁ ～k _n may be selected from the interval (1, 2], such as 1.2.

Referring to FIG. 4 , FIG. 4 is a schematic diagram of a curve of a brightness-gain mapping function according to an embodiment of the present invention.

In this example, only two segmentation points (thr _x , gain _x ) and (thr _y , gain _y ) are schematically shown, wherein the abscissa of the coordinate axis represents the brightness threshold, the ordinate represents the target brightness gain, thr _x and thr _y are two brightness thresholds as examples, and gain _x and gain _y are the corresponding target brightness gains. As can be seen from the figure, the target function corresponding to the brightness threshold interval [0, thr _x ] is a constant function Gain=gain ₀ , and the target functions corresponding to the brightness threshold interval (thr _x , thr _y ] and the brightness threshold interval (thr _y , 255] are both power functions. In an embodiment of the present invention, the above-mentioned piecewise function including at least two types of target functions is used to perform brightness gain mapping, and one of the target functions is a power function and the other target function is a constant function. Compared with the use of a simple whole-segment straight line mapping function or a stepped piecewise function composed of multiple constant functions for mapping, the mapping function of this implementation scheme is more in line with the visual perception of the human eye and can achieve better picture brightness adjustment and display effects.

Continuing to refer to FIG. 1 , in the specific implementation of step S14, the target pixels to be adjusted in the image block may be all pixels in the image block, or may be a portion of pixels, for example, pixels other than pixels whose chromaticity values fall within the target chromaticity interval. The brightness value of the target pixel to be adjusted specifically refers to the original brightness value (or brightness value before adjustment) of the target pixel.

Specifically, the chromaticity values of the image block (for example, the H value of the HSV format image, the U and/or V value of the YUV format image) can be histogram-statisticed to obtain a color map histogram; and then the remaining pixels falling outside the target chromaticity interval are used as the target pixels to be adjusted in the image block. The target chromaticity interval can be set according to the needs of the actual application scenario. For example, the chromaticity interval covered by the chromaticity values of each pixel in the portrait area of the display screen to be adjusted can be used as the target chromaticity interval to avoid brightness adjustment of the portrait area and ensure the display effect of the portrait area.

In a specific embodiment, the target pixel to be adjusted is a pixel outside the pixel located in the edge area of the image block (i.e., a pixel not located in the edge area of the image block), and the brightness value of the target pixel (i.e., the original brightness value or the brightness value before adjustment) can be directly input into the brightness-gain mapping function to determine the target brightness gain corresponding to the target pixel, and the product of the target brightness gain and the original brightness value of the target pixel is used as the adjusted brightness value of the target pixel.

In another specific implementation, since the display image to be adjusted is divided into several image blocks, if the content difference between different blocks is large, then the target brightness gain corresponding to each determined brightness threshold value is also correspondingly large, which will cause the adjusted display image to have obvious brightness difference between different blocks, affecting the display effect. In order to avoid such brightness difference between blocks, brightness smoothing processing can be performed between different image blocks. Smoothing processing includes many processing methods.

For example, for a pixel located in the edge area of an image block, before the brightness of the pixel is adjusted, a weighted average of the target brightness gains corresponding to each pixel in a preset sub-area around the pixel (the area spans different image blocks) is calculated as the final target brightness gain for adjusting the brightness value of the pixel.

For another example, for a pixel located in an edge area of an image block, after the brightness of the pixel is adjusted, a weighted average of the adjusted brightness values of each pixel in a preset sub-area (the area spans different image blocks) around the pixel is calculated as the actual adjusted brightness value of the pixel.

Regarding the above-mentioned inter-block brightness smoothing method, please refer to the relevant description of FIG. 5 below for details.

Referring to Figure 5, Figure 5 is a flowchart of a specific implementation of step S14 in Figure 1. In this implementation, the target pixel to be adjusted is a pixel located in the edge area of the image block, and the target brightness gain corresponding to the target pixel is determined according to the brightness-gain mapping function, which can specifically include steps S141 to S142.

In step S141, for each pixel in a preset sub-region around the target pixel, the brightness value of each pixel is substituted into the brightness gain mapping function of the image block to which it belongs, so as to obtain the target brightness gain corresponding to each pixel, wherein the preset sub-region includes pixels of at least one image block adjacent to the position of the image block to which the target pixel belongs.

In other words, the predetermined sub-region spans the image block to which the target pixel belongs and at least one image block adjacent to the image block.

In step S142, a weighted average of the target brightness gains corresponding to all pixels in the preset sub-region is taken as the target brightness gain corresponding to the target pixel.

Further, the brightness-gain mapping function is a piecewise function including a plurality of objective functions, each objective function having a corresponding brightness threshold interval and a corresponding preset brightness deviation, and each two adjacent objective functions are connected by a segmentation point. In the step S14, the brightness value of the target pixel is adjusted by using the target brightness gain, which may specifically include: determining the brightness threshold interval into which the brightness value of the target pixel falls, and obtaining a preset brightness deviation corresponding to the objective function to which the brightness threshold interval belongs, recorded as a target brightness deviation; calculating the product of the target brightness gain and the brightness value of the target pixel, and then taking the sum of the product and the target brightness deviation as the adjusted brightness value of the target pixel.

Specifically, the adjusted brightness value V′ of each target pixel may be determined using the following formula:

Among them, V′ represents the adjusted brightness value of the target pixel, V represents the original brightness value of the target pixel (that is, the brightness value before adjustment), a ₁ to a _n respectively represent the first coefficients of the 1st to nth power functions of the brightness-gain mapping function, b ₁ to b _n respectively represent the second coefficients of the 1st to nth power functions, c ₁ to c _n respectively represent the third coefficients of the 1st to nth power functions, k ₁ to k _n are respectively preset constants used to represent the powers of the 1st to nth power functions, gain ₀ represents a brightness gain constant, thr ₁ ′ to thr _n ′ respectively represent the 1st to nth target brightness thresholds, coef ₁ to coef _n represent preset brightness deviations corresponding to the 1st to nth power functions, and coef ₀ represents a preset brightness deviation corresponding to the constant function.

Furthermore, the preset brightness deviation corresponding to each objective function can be determined in the following manner: for each objective function in the brightness-gain mapping function, the horizontal coordinate of the segmentation point between the objective function and the adjacent previous objective function is used as the critical brightness value, and the critical brightness value is substituted into the objective function and the adjacent previous objective function respectively to obtain the corresponding first target brightness gain and second target brightness gain; the first product of the critical brightness value and the first target brightness gain, and the second product of the critical brightness value and the second target brightness gain are calculated respectively; the sum of the second product and the preset brightness deviation corresponding to the adjacent previous objective function is taken, and the first product is subtracted to obtain the preset brightness deviation corresponding to the objective function.

In a specific embodiment, the target function (ie, the constant function Gain=gain ₀ ) in the brightness threshold interval [0, thr ₁ ′] corresponds to a preset brightness deviation coef ₀ =0.

Right now,

... and so on.

In the embodiment of the present invention, each objective function is set to have a corresponding brightness deviation, and after calculating the product of the target brightness gain and the brightness value of the target pixel, the sum of the product and the corresponding target brightness deviation is used as the adjusted brightness value of the target pixel, so that the adjusted brightness values at the endpoints of each two adjacent objective functions remain consistent (rather than jumping). In this way, the uniformity of brightness adjustment can be improved, the brightness of the adjusted display screen can be avoided from suddenly changing, and the display effect can be improved.

6 , which is a schematic diagram of a mapping curve between a brightness value before adjustment and a brightness value after adjustment in an embodiment of the present invention.

As can be seen from the figure, in the brightness value interval [0, thr ₁ ], the mapping relationship between the corresponding adjusted brightness value V′ and the original brightness value (i.e., the brightness value before adjustment) V is a linear function mapping relationship, i.e., V′=V×gain ₀ ; when the brightness value is greater than thr ₁ , the mapping relationship between the adjusted brightness value V′ and the brightness value V before adjustment is a curve mapping relationship. In a specific embodiment, thr ₁ can be equal to the minimum target brightness threshold thr ₁ ′ among the target brightness thresholds. In addition, it can be seen from the mapping curves in the figure that the mapping curves corresponding to different brightness threshold intervals are all connected coherently without any jump points.

For more details about the mapping relationship between V′ and V, please refer to the previous description and will not be repeated here.

1, in the specific implementation of step S15, each processed image block is block-joined to obtain an adjusted display image. The joint position of each processed image block is the position of the image block before processing in the display image to be adjusted.

In the embodiment of the present invention, by dividing the display screen to be adjusted into a number of independent image blocks, the mapping function between brightness and brightness gain is determined with the image block as the granularity, so as to adjust the brightness of the pixels of each block respectively, a better and more refined brightness adjustment effect can be obtained, and compared with the existing scheme, the power consumption of the display driving device is reduced while improving the image display effect. Furthermore, in the embodiment of the present invention, the mapping relationship is determined without calculating the pixel difference of each pixel, but directly using a plurality of different brightness thresholds preset for each block and the brightness gain for mapping, which can significantly reduce the amount of calculation and the complexity of calculation, and improve the efficiency and real-time performance of brightness adjustment.

Furthermore, before block stitching is performed on each processed image block, the method further includes: for each target pixel located in the edge area of the processed image block, the weighted average value of the adjusted brightness values of each pixel in a preset sub-area around the target pixel is used to update the adjusted brightness value of the target pixel; wherein the preset sub-area includes pixels of at least one image block adjacent to the position of the image block to which the target pixel belongs. In this way, a smooth transition of the pixel brightness values in the edge area between the image blocks can also be achieved, thereby improving the display effect of the display picture after brightness adjustment.

FIG7 is a partial flow chart of another method for adjusting the brightness of a display screen in an embodiment of the present invention. The another method for adjusting the brightness of a display screen may include steps S11 to S15 shown in FIG1 , and may also include steps S71 to S73, wherein steps S71 to S73 may be performed after step S15. The following is an explanation of the differences from FIG1 .

In step S71, for each processed image block of the adjusted display frame, it is determined whether the difference in block brightness between the processed image block at the same position of the adjacent previous adjusted display frame is greater than a preset brightness difference.

The term "adjacent" specifically refers to the time or timing at which the display images are displayed on the display screen being adjacent.

In step S72, if the determination result is yes, then for each target pixel of the processed image block, the target pixel at the same position in the adjacent previous frame adjusted display image is determined.

In step S73, the adjusted brightness value of the target pixel in the processed image block is secondarily adjusted by using the target brightness gain corresponding to the target pixel and the average value of the target brightness gain corresponding to the target pixel at the same position, thereby obtaining a secondarily adjusted display image.

It is understandable that if the display contents of the same position of two adjacent display frames are greatly different, the corresponding target brightness gains will also be greatly different, which will cause flickering at a local position during video playback. Therefore, in an embodiment of the present invention, the above scheme can be used to smooth the target brightness gains of the same position of the two preceding and succeeding display frames. In this way, the flickering problem can be avoided and the smoothness and display effect of the pictures between different frames can be improved.

Referring to FIG8 , FIG8 is a schematic diagram of a structure of a device for adjusting the brightness of a display screen according to an embodiment of the present invention. The device for adjusting the brightness of a display screen may include:

An image block acquisition module 81 is used to acquire image blocks to be processed and determine a block brightness value of each image block, wherein the image blocks are obtained by dividing the display image to be adjusted into blocks;

A corresponding relationship determination module 82, configured to determine, based at least on the block brightness value of the image block, a target brightness gain corresponding to each preset brightness threshold of the image block, wherein each image block has a plurality of preset different brightness thresholds, and the larger the brightness threshold, the smaller the corresponding target brightness gain;

A function fitting module 83 is used to perform function fitting using each brightness threshold of the image block and its corresponding target brightness gain to obtain a brightness-gain mapping function of the image block;

An image block brightness adjustment module 84 is used to determine, for each target pixel to be adjusted in the image block, a target brightness gain corresponding to the target pixel according to the brightness-gain mapping function, and use the target brightness gain to perform brightness adjustment on the brightness value of the target pixel to determine a processed image block;

The image block stitching module 85 is used to stitch the processed image blocks to obtain an adjusted display image.

Regarding the principle, specific implementation and beneficial effects of the display screen brightness adjustment device, please refer to the relevant description of the display screen brightness adjustment method shown in the above text and any embodiment shown in Figures 1 to 7, which will not be repeated here.

The embodiment of the present invention further provides a storage medium, such as a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method for adjusting the brightness of a display screen shown in any of the embodiments shown in Figures 1 to 7 are executed. The computer-readable storage medium may include a non-volatile memory or a non-transitory memory, and may also include an optical disk, a mechanical hard disk, a solid-state hard disk, etc.

Specifically, in the embodiment of the present invention, the processor may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

It should also be understood that the memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link DRAM (SLDRAM) and direct rambus RAM (DR RAM).

An embodiment of the present invention also provides a terminal, including a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and when the processor runs the computer program, the steps of the method for adjusting the brightness of the display screen shown in any embodiment shown in Figures 1 to 7 are executed.

An embodiment of the present invention further provides a computer program product, including a computer program, which, when executed by a processor, executes the steps of the method for adjusting the brightness of a display screen in any of the embodiments shown in FIG. 1 to FIG. 7 .

It should be understood that the term "and/or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character "/" in this article indicates that the associated objects before and after are in an "or" relationship.

The "plurality" appearing in the embodiments of the present application refers to two or more.

The first, second, etc. descriptions appearing in the embodiments of the present application are only used for illustration and distinction of the description objects. There is no order, nor do they indicate any special limitation on the number of devices in the embodiments of the present application, and cannot constitute any limitation on the embodiments of the present application.

It should be noted that the serial numbers of the steps in this embodiment do not limit the execution order of the steps.

Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims (15)

1. A method for adjusting the brightness of a display screen, comprising: Acquire an image block to be processed, and determine a block brightness value of each image block, wherein the image block is obtained by dividing the display image to be adjusted into blocks; At least based on the block brightness value of the image block, determine the target brightness gain corresponding to each preset brightness threshold of the image block, wherein each image block has a plurality of preset different brightness thresholds, and the larger the brightness threshold, the smaller the corresponding target brightness gain; Performing function fitting using each brightness threshold of the image block and its corresponding target brightness gain to obtain a brightness-gain mapping function of the image block; For each target pixel to be adjusted in the image block, determine a target brightness gain corresponding to the target pixel according to the brightness-gain mapping function, and use the target brightness gain to perform brightness adjustment on the brightness value of the target pixel to determine a processed image block; The processed image blocks are block-joined to obtain an adjusted display image. 2. The method according to claim 1, characterized in that determining the target brightness gain corresponding to each preset brightness threshold of the image block at least based on the block brightness value of the image block comprises: Searching for a brightness gain corresponding to the block brightness value of the image block from a preset brightness interval-brightness gain mapping relationship table, and recording it as a brightness gain lower limit value, wherein the brightness interval-brightness gain mapping relationship table includes a one-to-one correspondence between a plurality of pre-divided brightness intervals and a plurality of preset brightness gains; Between the brightness gain lower limit value and a preset brightness gain upper limit value, a plurality of target brightness gains including the brightness gain lower limit value are determined, and the plurality of target brightness gains are matched one by one with a plurality of different brightness thresholds of the image block; After the plurality of target brightness gains are sorted, the difference between every two target brightness gains with adjacent numerical values falls within a preset brightness difference interval. 3. The method according to claim 1, characterized in that the brightness thresholds of the image block and their corresponding target brightness gains are used to perform function fitting to obtain the brightness-gain mapping function of the image block, comprising: Selecting at least one target brightness threshold value from among the brightness threshold values of the image block; Each target brightness threshold and the corresponding target brightness gain are used as the abscissa and ordinate of a single segmentation point, respectively, to obtain at least one segmentation point; Each brightness threshold value of the image block and its corresponding target brightness gain are used as the horizontal coordinate and the vertical coordinate of the fitting point respectively, and a plurality of preset target functions and each segmentation point are used to perform piecewise function fitting to obtain the brightness-gain mapping function. 4. The method according to claim 3 is characterized in that the multiple preset objective functions are selected from: constant function, linear function, and power function. 5. The method according to claim 3, characterized in that the plurality of preset objective functions include at least two types of objective functions; The first objective function in the brightness-gain mapping function is a constant function, and the other objective functions are all power functions. 6. The method according to claim 1, wherein the target pixel to be adjusted is a pixel located in an edge area of the image block; Determining a target brightness gain corresponding to the target pixel according to the brightness-gain mapping function includes: For each pixel in a preset sub-region around the target pixel, the brightness value of each pixel is substituted into the brightness gain mapping function of the image block to which it belongs, so as to obtain the target brightness gain corresponding to each pixel, wherein the preset sub-region includes pixels of at least one image block adjacent to the position of the image block to which the target pixel belongs; The weighted average of the target brightness gains corresponding to all pixels in the preset sub-area is used as the target brightness gain corresponding to the target pixel. 7. The method according to claim 1, characterized in that, before performing block splicing on each processed image block, the method further comprises: For each target pixel located in the edge area of the processed image block, the adjusted brightness value of the target pixel is updated by taking the weighted average of the adjusted brightness values of the pixels in the preset sub-area around the target pixel; The preset sub-region includes pixels of at least one image block adjacent to the position of the image block to which the target pixel belongs. 8. The method according to claim 1, characterized in that the brightness-gain mapping function is a piecewise function including a plurality of objective functions, each objective function has a corresponding brightness threshold interval and a corresponding preset brightness deviation, and every two adjacent objective functions are connected by a piecewise point; The step of using the target brightness gain to adjust the brightness value of the target pixel includes: Determine the brightness threshold interval that the brightness value of the target pixel falls into, and obtain a preset brightness deviation corresponding to the objective function to which the brightness threshold interval belongs, recorded as a target brightness deviation; The product of the target brightness gain and the brightness value of the target pixel is calculated, and then the sum of the product and the target brightness deviation is used as the adjusted brightness value of the target pixel. 9. The method according to claim 1, characterized in that after obtaining the adjusted display picture, the method further comprises: For each processed image block of the adjusted display picture, determining whether a difference in block brightness between the processed image block at the same position of the adjacent processed image block at the same position of the previous adjusted display picture is greater than a preset brightness difference; If the judgment result is yes, then for each target pixel of the processed image block, determining the target pixel at the same position in the adjusted display picture of the adjacent previous frame; The adjusted brightness value of the target pixel of the processed image block is secondarily adjusted by using the target brightness gain corresponding to the target pixel and the average value of the target brightness gain corresponding to the target pixel at the same position, thereby obtaining a secondarily adjusted display image. 10 . The method according to claim 1 , wherein the pixels to be adjusted in the image block are selected from the remaining pixels except the pixels whose chrominance values fall within the target chrominance interval. 11. The method according to claim 1, wherein the block brightness value of the image block is selected from any one of the following: The average brightness value of each pixel of the image block, the maximum brightness value of each pixel of the image block, and the minimum brightness value of each pixel of the image block. 12. A device for adjusting the brightness of a display screen, comprising: An image block acquisition module, used to acquire an image block to be processed and determine a block brightness value of each image block, wherein the image block is obtained by dividing the display image to be adjusted into blocks; a corresponding relationship determination module, used to determine a target brightness gain corresponding to each preset brightness threshold of the image block based at least on the block brightness value of the image block, wherein each image block has a plurality of preset different brightness thresholds, and the larger the brightness threshold, the smaller the corresponding target brightness gain; A function fitting module, used to perform function fitting using each brightness threshold of the image block and its corresponding target brightness gain to obtain a brightness-gain mapping function of the image block; An image block brightness adjustment module is used to determine, for each target pixel to be adjusted in the image block, a target brightness gain corresponding to the target pixel according to the brightness-gain mapping function, and use the target brightness gain to perform brightness adjustment on the brightness value of the target pixel to determine a processed image block; The image block stitching module is used to stitch the processed image blocks to obtain an adjusted display image. 13. A storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, executes the steps of the method for adjusting the brightness of a display screen according to any one of claims 1 to 11. 14. A terminal comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, wherein the processor executes the steps of the method for adjusting the brightness of a display screen as claimed in any one of claims 1 to 11 when running the computer program. 15. A computer program product, comprising a computer program, characterized in that when the computer program is executed by a processor, the steps of the method for adjusting the brightness of a display screen according to any one of claims 1 to 11 are executed.