Gray scale compensation method and device, medium, electronic equipment and program product

Abstract

The invention provides a gray scale compensation method and device, a medium, electronic equipment and a program product. The method comprises the following steps: determining the actual current of each pixel point according to the global average current of a to-be-displayed image on a display panel and the column current weight of each pixel point; the global average current is determined according to the sum of the currents of all pixel points, and the current of each pixel point is determined in a pre-constructed first current lookup table through the gray-scale value of the pixel point; for each pixel point in the to-be-displayed image, determining a target current of the pixel point in a pre-constructed second current lookup table according to maximum gray scale components in R, G and B channels of the pixel point; and determining a compensation coefficient of each pixel point in a group of pre-constructed compensation coefficient lookup tables according to the actual current and the target current of each pixel point. According to the invention, the calculation involved in the algorithm is divided into a plurality of lookup tables according to the calculation process and provided for the FPGA, so that the design complexity, cost and power consumption in the FPGA are reduced.

Description

Technical Field

[0001] The present invention relates to the field of image processing, and in particular to a grayscale compensation method, device, medium, electronic equipment and program product. Background Art

[0002] During the manufacturing process of the display panel, due to the limitation of the processing technology, the magnitude of the current will be affected by many factors, such as the mobility and threshold voltage of the TFT (thin film transistor), the driving voltage of the OLED (organic light emitting diode), and the overall power supply voltage. The fluctuation and difference of these parameters will lead to inconsistent display brightness of the same gray scale at different voltage drop levels on the display panel. Figure 1 As shown, for the same picture, the black background is brighter than the white background. This phenomenon is the IR Drop phenomenon in the display panel.

[0003] The IR Drop compensation method (IRC algorithm for short) aims to eliminate the IR Drop phenomenon. However, when implementing the algorithm using FPGA (Field Programmable Gate Array), a large amount of hardware resources and clock cycles are required, which not only increases the complexity of the design, but also increases the cost and power consumption. Therefore, a method that can reduce the design complexity, reduce the use of hardware resources, and reduce power consumption is urgently needed. Summary of the invention

[0004] The present invention provides a grayscale compensation method, device, medium, electronic equipment and program product to solve the deficiencies in the related art.

[0005] According to a first aspect of an embodiment of the present invention, a grayscale compensation method is provided, the method comprising: determining an actual current of each pixel point based on a global average current of an image to be displayed on a display panel and a column current weight of each pixel point; wherein the global average current is determined based on the sum of currents of all pixel points, and the current of each pixel point is determined in a pre-constructed first current lookup table through the grayscale value of the pixel point; the column current weight is determined based on the average value of the currents of each pixel point in the same column; for each pixel point in the image to be displayed, determining a target current of the pixel point in a pre-constructed second current lookup table based on the maximum grayscale component in its R, G, and B channels; determining a compensation coefficient for each pixel point in a pre-constructed set of compensation coefficient lookup tables based on the actual current and target current of each pixel point; and determining a target grayscale value for each pixel point based on the compensation coefficient and grayscale value of each pixel point.

[0006] In some embodiments, before determining the actual current of each pixel, the method further includes: if the image to be displayed is 8 bits, converting the image to be displayed to 12 bits.

[0007] In some embodiments, determining the actual current of each pixel point based on the global average current of the image to be displayed on the display panel and the column current weight of each pixel point includes: determining the current of each pixel point in a pre-constructed first current lookup table according to the grayscale value of each pixel point in the image to be displayed; determining the global average current according to the sum of the currents of all pixels points divided by the number of pixels; determining the column average current according to the sum of the currents of all pixels points in each column and the number of pixels in the column; determining the column current weight according to a preset power of the column average current, and the column current weights corresponding to each pixel point in the same column are the same; and obtaining the actual current of each pixel point according to the product of the global average current and the column current weight of each pixel point.

[0008] In some embodiments, determining the current of each pixel in a pre-constructed first current lookup table according to the grayscale value of each pixel in the image to be displayed includes:

[0009] For each pixel in the image to be displayed, a first candidate current corresponding to the upper 8 bits of the 12-bit grayscale value of the pixel is obtained from a pre-constructed first current lookup table, and the upper 8-bit value is added by 1 to obtain a second candidate current corresponding to the value after the addition operation;

[0010] If the first candidate current is greater than the second candidate current, obtaining a difference between the first candidate current and the second candidate current, performing a bitwise operation on the product of the difference and the lower 4 bits of the 12-bit grayscale value to obtain a first interpolation current, and obtaining a current of the pixel point according to the first candidate current and the first interpolation current;

[0011] If the first candidate current is less than the second candidate current, the difference between the second candidate current and the first candidate current is obtained, and a bit operation is performed on the product of the difference and the lower 4 bits of the 12-bit grayscale value to obtain a second interpolation current, and the current of the pixel point is obtained based on the first candidate current and the second interpolation current.

[0012] In some embodiments, the first current lookup table is constructed based on the following steps: according to the correlation between grayscale values ​​and current values, all values ​​of grayscale values ​​within a preset range are traversed to obtain a first current lookup table; wherein the preset range is [0, 256].

[0013] In some embodiments, the compensation coefficient of each pixel is determined in a pre-constructed set of compensation coefficient lookup tables based on the actual current and target current of each pixel, including: for each pixel, in a pre-constructed first compensation coefficient lookup table, obtaining the brightness adjustment ratio of the grayscale value of the pixel when the contrast changes; according to the correlation between the target current of the pixel and the adjustment ratio, calculating the first current for controlling the actual brightness of the pixel; in a pre-constructed second compensation coefficient lookup table, obtaining the first coefficient corresponding to the first current; according to the correlation between the actual current of the pixel and the adjustment ratio, calculating the second current for controlling the actual brightness of the pixel; in a pre-constructed third compensation coefficient lookup table, obtaining the second coefficient corresponding to the second current; and calculating the compensation coefficient of the pixel according to the product of the first coefficient and the second coefficient.

[0014] In some embodiments, the second compensation coefficient lookup table is constructed based on the following steps: for a first current with a value range of [0,1], the value range is equally spaced into 256 nodes; an exponential operation is performed on each interval node, and the exponential operation result is shifted left by 12 bits to obtain a first coefficient corresponding to each node; and a second compensation coefficient lookup table is constructed based on each node and the first coefficient corresponding to each node.

[0015] In some embodiments, after determining the compensation coefficient of each pixel point, the method further includes: obtaining a correction coefficient corresponding to the actual current of each pixel point in a pre-constructed correction coefficient lookup table; and correcting the compensation coefficient of each pixel point using the correction coefficient to obtain a corrected compensation coefficient.

[0016] In some embodiments, the using the correction coefficient to correct the compensation coefficient of each pixel to obtain the corrected compensation coefficient includes:

[0017] If the compensation coefficient of the pixel point is greater than or equal to a preset value, obtaining a difference between the compensation coefficient and the preset value, obtaining a product of the difference and the correction coefficient, calculating a quotient of the product and the preset value, and taking the sum of the quotient and the preset value as the corrected compensation coefficient;

[0018] If the compensation coefficient of the pixel point is less than a preset value, the difference between the preset value and the compensation coefficient is obtained, the product of the difference and the correction coefficient is obtained, and the difference between the preset value and the product is used as the corrected compensation coefficient.

[0019] According to a second aspect of an embodiment of the present invention, a grayscale compensation device is provided, the device comprising: an actual current determination unit, for determining the actual current of each pixel point according to the global average current of the image to be displayed on the display panel and the column current weight of each pixel point; wherein the global average current is determined according to the sum of the currents of all the pixels, and the current of each pixel point is determined in a pre-constructed first current lookup table through the grayscale value of the pixel point; the column current weight is determined according to the average value of the currents of each pixel point in the same column; a target current determination unit, for determining, for each pixel point in the image to be displayed, the target current of the pixel point in a pre-constructed second current lookup table according to the maximum grayscale component in its R, G, and B three channels; a compensation coefficient determination unit, for determining the compensation coefficient of each pixel point in a pre-constructed set of compensation coefficient lookup tables according to the actual current and target current of each pixel point; a compensation unit, for determining the target grayscale value of each pixel point according to the compensation coefficient and grayscale value of each pixel point.

[0020] According to a third aspect of an embodiment of the present invention, there is provided a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, any method described in the first aspect is implemented.

[0021] According to a fourth aspect of an embodiment of the present invention, there is provided an electronic device, comprising: a processor; and a memory for storing processor-executable instructions; wherein the processor is configured to execute any one of the methods described in the first aspect.

[0022] According to a fifth aspect of an embodiment of the present invention, there is provided a computer program product, including a computer program and instructions, wherein when the computer program / instructions are executed by a processor, any method described in the first aspect is implemented.

[0023] According to the above embodiments, the present invention determines the actual current of each pixel point according to the global average current of the image to be displayed on the display panel and the column current weight of each pixel point; wherein the global average current is determined according to the sum of the currents of all pixels, and the current of each pixel point is determined in a pre-constructed first current lookup table through the grayscale value of the pixel point; for each pixel point in the image to be displayed, the target current of the pixel point is determined in a pre-constructed second current lookup table according to the maximum grayscale component in its R, G, and B channels; the compensation coefficient of each pixel point is determined in a pre-constructed set of compensation coefficient lookup tables according to the actual current and target current of each pixel point; the target grayscale value of each pixel point is determined according to the compensation coefficient and grayscale value of each pixel point. That is, the present invention splits the calculations involved in the algorithm into multiple lookup tables according to the calculation process and provides them to the FPGA, thereby achieving the purpose of converting the floating-point operation of the algorithm into fixed-point operation, reducing the complexity, cost and power consumption of the design in the FPGA.

[0024] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0026] Figure 1 is a schematic diagram showing an IR Drop phenomenon according to an embodiment of the present invention.

[0027] Figure 2 is a flow chart showing a grayscale compensation method according to an embodiment of the present invention.

[0028] Figure 3 FIG. 4 is a schematic diagram showing a table lookup process according to an embodiment of the present invention.

[0029] Figure 4 The figure is a flow chart showing a method for determining a compensation coefficient according to an embodiment of the present invention.

[0030] Figure 5 is a schematic diagram of a grayscale compensation device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0032] The IR Drop (voltage drop) phenomenon on the display panel will cause inconsistent brightness at the same voltage drop level even with the same grayscale. In related technologies, the IRC algorithm is usually used to eliminate the IR Drop phenomenon, making the brightness of the display panel more uniform. However, the floating-point operations involved in the algorithm will significantly increase the hardware resource requirements and clock cycle execution time when implemented using FPGA.

[0033] In view of this, the present invention provides a grayscale compensation method, which can convert floating-point operations in algorithms or data paths into fixed-point operations (i.e., fixed-point conversion), thereby reducing the use of hardware resources such as logic units and memories, and improving system performance.

[0034] Since floating-point operations involve accurate representation and calculation of floating-point numbers, more hardware resources and clock cycles are required to execute, while fixed-point operations use integers with fixed bit widths to represent numbers, and similar functions can be achieved by using simpler algorithms and hardware structures. Therefore, in FPGA design, converting floating-point operations to fixed-point operations can reduce design complexity, cost, and power consumption.

[0035] In FPGA, the Look-Up-Table (LUT) is a basic logic resource, which is usually used to implement Boolean logic functions. The LUT method is suitable for mapping inputs to discrete output values. For the look-up table method, it is necessary to first determine the input range and output range of the function. Then, each possible value of the input is mapped to an output value, and these mapping relationships are stored in the LUT of the FPGA. When the input arrives, the FPGA will find the output value corresponding to the input in the LUT and output the value. Secondly, it can estimate the value of any point by interpolating between known data points. Therefore, in the present invention, the calculations involved in the algorithm are split and mapped into multiple LUT tables according to the calculation process, and provided to the FPGA for calculation and interpolation.

[0036] The following embodiments will specifically illustrate the method provided by the present invention in conjunction with the accompanying drawings.

[0037] Figure 2 is a flow chart of a grayscale compensation method according to an embodiment of the present invention. Figure 2As shown, a grayscale compensation method provided by the present invention may include the following steps 201 to 204.

[0038] In step 201 , the actual current of each pixel is determined according to the global average current of the image to be displayed on the display panel and the column current weight of each pixel.

[0039] Among them, the global average current is determined according to the sum of the currents of all pixels, and the current of each pixel is determined by the grayscale value of the pixel in a pre-constructed first current lookup table; the column current weight is determined according to the average value of the currents of each pixel in the same column.

[0040] In step 202, for each pixel in the image to be displayed, a target current of the pixel is determined in a pre-constructed second current lookup table according to the maximum grayscale component in the three channels R, G, and B of the pixel.

[0041] In step 203, the compensation coefficient of each pixel is determined in a pre-constructed set of compensation coefficient lookup tables according to the actual current of each pixel and the target current.

[0042] In step 204, a target grayscale value of each pixel is determined according to the compensation coefficient and the grayscale value of each pixel.

[0043] It can be seen from the above steps 201 to 204 that the present invention maps the process involving floating-point operations in the algorithm into multiple LUT tables in advance, namely a first current lookup table, a second current lookup table, and a group of compensation coefficient lookup tables. During the calculation process, when floating-point operations are involved, the corresponding output value is obtained by looking up the table, thereby achieving the purpose of converting floating-point operations into fixed-point operations and reducing the design complexity of FPGA.

[0044] That is to say, the present invention determines the actual current of each pixel point according to the global average current of the image to be displayed on the display panel and the column current weight of each pixel point; wherein the global average current is determined according to the sum of the currents of all pixels points, and the current of each pixel point is determined in a pre-constructed first current lookup table through the grayscale value of the pixel point; for each pixel point in the image to be displayed, the target current of the pixel point is determined in a pre-constructed second current lookup table according to the maximum grayscale component in its three channels of R, G, and B; the compensation coefficient of each pixel point is determined in a pre-constructed set of compensation coefficient lookup tables according to the actual current and target current of each pixel point; the target grayscale value of each pixel point is determined according to the compensation coefficient and grayscale value of each pixel point. That is, the present invention splits the calculations involved in the algorithm into multiple lookup tables according to the calculation process and provides them to the FPGA, thereby achieving the purpose of converting the floating-point operation of the algorithm into fixed-point operation, reducing the complexity, cost and power consumption of the design in the FPGA.

[0045] In this embodiment, in order to be compatible with the 12-bit input signal source of some display panels and to improve the accuracy in the FPGA and reduce the quantization error, when the image to be displayed on the display panel is 8 bits, the image to be displayed is converted to 12 bits.

[0046] In one example, an 8-bit image to be displayed can be converted to a 12-bit image through bit operations. Specifically, the original 8-bit image data is read, the grayscale value of each pixel is shifted left by 4 bits, the lower 4 bits after the left shift are filled with 0, and the processed data is stored in a 12-bit image format.

[0047] In another example, an 8-bit image to be displayed can be converted to 12 bits by using a dithering method. Specifically, first, the 8-bit image data is converted into discrete values ​​in grayscale or color space. Then, a dithering algorithm is applied to introduce slight color changes in the image, which can be random, ordered, or based on error diffusion. Through the processing of the dithering algorithm, the image will visually present a smoother color transition and a higher color depth effect. Finally, the processed image data is saved in a 12-bit image format.

[0048] In FPGA, the number of input bits of LUT is usually 4 or 6 bits. For example, a 4-input LUT is actually a memory with 4 address bits and 1 data bit, which can store 16 bits of data. When the number of bits of input data is much larger than the input of a LUT, multiple LUTs need to be cascaded to implement the logic. However, cascading will cause delays and restrict the operating frequency of the system, so using a LUT with fewer inputs can better save area and resources. Based on the above reasons, when processing 12-bit image data, the present invention uses two LUTs in cascade to reduce delay, that is, to construct an 8-bit LUT table. When looking up the table, since the grayscale value is 12 bits, the upper 8 bits of the 12 bits are used to look up the table, and the lower 4 bits are used for interpolation to obtain the numerical value corresponding to the 12-bit grayscale value.

[0049] In the following embodiments, the construction process of the first current lookup table is first described.

[0050] In this embodiment, according to the correlation between the grayscale value and the current value, all values ​​of the grayscale value within a preset range are traversed to obtain a first current lookup table; wherein the preset range is [0, 256].

[0051] For example, the correlation between the grayscale value and the current value can be seen in the following formula (1).

[0052]

[0053] In the above formula, i sP(x,y) represents the current value at the pixel point P(x,y), cw P Indicates the effect of current on voltage drop at pixel point P, g P The exponential coefficient representing the power relationship between the grayscale value at the pixel point P and the current load.

[0054] By traversing all values ​​of [0, 256], a first current lookup table between grayscale values ​​and current values ​​can be obtained.

[0055] It should be noted that since the 8-bit image data is 0-255, converting 8 bits to 12 bits is to shift left four bits, that is, multiply by 16. The largest 8-bit number is 255*16=4080, and the 12-bit maximum value is 4095. In order to prevent out-of-range data from appearing during the calculation process, the preset range is set to [0, 256], that is, 257 numbers are generated, and the 257th number is used to interpolate the value between 4080 and 4095.

[0056] In some embodiments, the R, G, and B channels corresponding to the same pixel point can be compensated separately. In this case, all grayscale values ​​within a preset range can be traversed according to the correlation between the grayscale component and the current value of each channel to obtain a lookup table corresponding to each channel.

[0057] The relationship between the grayscale component and the current value of each channel can be seen in the following formulas (1-1), (1-2) and (1-3).

[0058]

[0059] In the above formula, i sR(x,y) Represents the current value of the R channel at the pixel point P(x,y), i sG(x,y) Represents the current value of the G channel at the pixel point P(x,y), i sB(x,y) Indicates the current value of channel B at pixel point P(x,y), cw R Indicates the effect of R channel on voltage drop, cw G Indicates the effect of G channel on the voltage drop, cw B Indicates the effect of channel B on the voltage drop, g R The exponential coefficient representing the relationship between the grayscale value of the R channel and the power of the current load, g G The exponential coefficient representing the relationship between the grayscale value of the G channel and the power of the current load, g B The exponential coefficient that represents the power relationship between the grayscale value of channel B and the current load. R 、cw G 、cw B , g R , g G and B The parameter values ​​need to be obtained by actual measurement or calculation.

[0060] According to the above formula, we can traverse all values ​​of [0, 256] to get R(x, y) and i sR(x,y) The lookup table LUT00, G(x,y) and i sG(x,y) The lookup table LUT01 and B(x,y) and i sB(x,y) Lookup table LUT02.

[0061] R(x,y) <![CDATA[i sR(xy) ]]> 0 0 1 3 2 6 ... ... 256 2424

[0062] LUT00

[0063] G(x,y) <![CDATA[i sG(xy) ]]> 0 0 1 1 2 1 ... ... 256 721

[0064] LUT01

[0065] B(x,y) <![CDATA[i sB(xy) ]]> 0 0 1 1 2 1 ... ... 256 950

[0066] LUT02

[0067] When calculating the actual current of each pixel, it is necessary to calculate based on the global average current of the image to be displayed and the column current weight of each pixel, that is, according to the grayscale value of each pixel in the image to be displayed, determine the current of each pixel in the pre-constructed first current lookup table; determine the global average current according to the total current of all pixels divided by the number of pixels; determine the column average current according to the total current of all pixels in each column and the number of pixels in the column; determine the column current weight according to the preset power of the column average current, and the column current weights corresponding to each pixel in the same column are the same; and obtain the actual current of each pixel according to the product of the global average current and the column current weight of each pixel.

[0068] After the current of each pixel is determined according to the grayscale value of each pixel in the pre-constructed first current lookup table, the global average current can be determined according to the sum of the currents of all pixels divided by the number of pixels.

[0069] Still taking the compensation of the grayscale component of each channel as an example, the global average current can be calculated according to the following formula (2).

[0070]

[0071] Among them, I s represents the sum of the currents of all pixels in the circuit, also known as global current estimation; h represents the number of rows in the image, w represents the number of columns in the image, and i sm represents the global average current. sm Is a scalar representing the compression level of the current image.

[0072] When the current of each pixel is known, the column average current can be determined according to the sum of the currents of all pixels in each column and the number of pixels in the column, and the column current weight can be determined according to a preset power of the column average current.

[0073] The column average current can be determined by formula (3).

[0074]

[0075] In the formula, i sl represents the column average current, and c represents the number of channels.

[0076] In some embodiments, The value of is the column current weight iw sl , that is, the preset power can be set to In this embodiment, the preset power can be set according to the gamma value of the screen. For example, when the gamma of the screen is 2.4, the preset power can be set to This embodiment does not limit this.

[0077] Since the number of LUT addresses is 256, but the image data to be processed is 12 bits, the values ​​need to be truncated and interpolated when looking up the table. Figure 3 The table lookup process is introduced in detail.

[0078] Figure 3 FIG. 1 is a schematic diagram showing a table lookup process according to an embodiment of the present invention. Figure 3 As shown, according to the grayscale value of each pixel in the image to be displayed, the current of each pixel is determined in a pre-constructed first current lookup table, including the following steps 301 to 305.

[0079] In step 301, a first candidate current corresponding to the upper 8 bits of the 12-bit grayscale value of the pixel is obtained from a pre-constructed first current lookup table.

[0080] In step 302, an addition operation is performed on the upper 8-bit value to obtain a second candidate current corresponding to the value after the addition operation.

[0081] In step 303 , if the first candidate current is greater than the second candidate current, step 304 is executed; otherwise, step 305 is executed.

[0082] In step 304, the difference between the first candidate current and the second candidate current is obtained, and a bit operation is performed on the product of the difference and the lower 4 bits of the 12-bit grayscale value to obtain a first interpolation current, and the current of the pixel point is obtained based on the first candidate current and the first interpolation current.

[0083] In step 305, the difference between the second candidate current and the first candidate current is obtained, and a bit operation is performed on the product of the difference and the lower 4 bits of the 12-bit grayscale value to obtain a second interpolation current, and the current of the pixel point is obtained based on the first candidate current and the second interpolation current.

[0084] In this embodiment, when looking up a table, the upper 8 bits (ie, 0 to 255) of the 12-bit value are intercepted for table lookup, and the lower 4 bits are used for interpolation.

[0085] For example, assuming that the 12-bit value is 1382, the value corresponding to the upper 8 bits is 86, and the value corresponding to the lower 4 bits is 6. The first candidate current (denoted as V0) and the second candidate current (denoted as V1) corresponding to the 86th and 87th addresses in the first current lookup table are searched.

[0086] If V0>V1, then the value of (V0-V1)*6 / 16 (*here, 4 bits are shifted rightward to implement the division by 16 operation) is calculated and rounded to obtain the first interpolation current, recorded as V', and finally the current V of the pixel point is V0-V'.

[0087] If V0 < V1, calculate the value of (V1 - V0) * 6 / 16 and round it to obtain the second interpolated current, denoted as V’. Finally, the current V of this pixel is V = V0 + V’.

[0088] It should be noted that in the above table - lookup method, the values from 0 to 256 in the first current lookup table are the addresses of 12 - bit data, rather than the grayscale values. All subsequent table - lookup operations use the above table - lookup method.

[0089] In this embodiment, the construction process of the second current lookup table is similar to that of the first current lookup table. The correlation relationship between the maximum grayscale component and the target current can be seen in formula (4).

[0090]

[0091] where, i s ′ represents the target current at the pixel point (x, y), max c (x, y) represents the maximum grayscale component in the R, G, B channels of the pixel point with coordinates (x, y), cw c represents the weight of the maximum grayscale component in the three channels, g c represents the exponential coefficient of the power relationship between the maximum grayscale component in the three channels and the current load.

[0092] Exemplarily, by traversing [0, 256], a mapping table LUT03 of max c (x, y) and i s ′ can be constructed.

[0093] <![CDATA[max c (x,y)]]> <![CDATA[i s ′ ]]> 0 0 1 0 2 0 ... ... 255 1023 256 1024

[0094] LUT03

[0095] Given the second current lookup table, for each pixel point in the to - be - displayed image, its target current can be determined in the second current lookup table according to the maximum grayscale component in its R, G, B channels.

[0096] For ease of understanding, in the following embodiments, the process of calculating the compensation coefficient will be described first, then it will be introduced that in this embodiment, in order to achieve fixed - point operation, the calculation process is split and mapped into multiple compensation - coefficient lookup tables, and finally the use of multiple compensation - coefficient lookup tables will be introduced.

[0097] It should also be noted that the following embodiments are described using the compensation coefficient calculation process for the three channels of R, G, and B as an example, and the compensation coefficient calculation process for a pixel point is similar to the compensation coefficient calculation process for any channel, and will not be repeated in this embodiment.

[0098] The calculation formulas for the compensation coefficients of the three channels R, G, and B are shown in the following formulas (5-1), (5-2), and (5-3).

[0099]

[0100] Wherein, ratioR(x,y) represents the compensation coefficient of the R channel at the pixel point (x,y), which will be referred to as ratioR in the following text; ratioG(x,y) represents the compensation coefficient of the G channel at the pixel point (x,y), which will be referred to as ratioG in the following text; ratioB(x,y) represents the compensation coefficient of the B channel at the pixel point (x,y), which will be referred to as ratioB in the following text; i s ′ (x,y) Represents the target current at the pixel point (x, y), which will be referred to as i in the following s ′ ;i s(x,y) Represents the actual current at the pixel point (x, y), which will be referred to as i in the following s ; L(1,1) represents the lowest brightness; L(1,0) represents the highest brightness; g 0R The exponential coefficient that represents the relationship between the grayscale value of the R channel and the power of the current load when the voltage drop is maximum; g 1R The exponential coefficient that represents the relationship between the grayscale value of the R channel and the power of the current load when the voltage drop is minimum; g 0G The exponential coefficient that represents the power relationship between the grayscale value of the G channel and the current load when the voltage drop is maximum; g 1G The exponential coefficient that represents the power relationship between the grayscale value of the G channel and the current load when the voltage drop is minimum; g 0B The exponential coefficient that represents the power relationship between the grayscale value of channel B and the current load when the voltage drop is maximum; g 1B The exponential coefficient that represents the power relationship between the grayscale value of channel B and the current load when the voltage drop is minimum; g R =RminG, g G =GminG, g B =BminG, RminG, GminG, BminG respectively represent the exponential coefficients of the relationship between the grayscale value of each channel of R, G, B and the power of the current load when the voltage drop is maximum.

[0101] Grayscale p in i s The brightness is:

[0102] L(p)=L model(p,i s )

[0103] when i s = 0, the highest brightness is achieved; when i s When =1, the lowest brightness is achieved.

[0104] L1 represents the brightness of a single pixel when the voltage drop is maximum.

[0105] make:

[0106]

[0107] Formulas (6-1), (6-2) and (6-3) are all obtained after measuring the brightness, where g1 and g0 are also obtained through brightness fitting.

[0108] Based on equations (6-1), (6-2) and (6-3), equations (5-1), (5-2) and (5-3) can be decomposed into:

[0109]

[0110] In the above formulas (7-1), (7-2) and (7-3), Equivalent to

[0111] This embodiment converts the floating-point operations involved in equations (7-1), (7-2) and (7-3) into fixed-point operations. First, LR is calculated. 1 / 0 LG 1 / 0 , LB 1 / 0 .

[0112] According to the formula, we can traverse all values ​​of [0, 256] to get R, G, B and LR 1 / 0 LG 1 / 0 , LB 1 / 0 The first compensation coefficient lookup tables LUT04, LUT05, and LUT06.

[0113]

[0114]

[0115] LUT04

[0116] G <![CDATA[LG 1 / 0 ]]> 0 0 1 3871 2 3370 ... ... 256 1278

[0117] LUT05

[0118] B <![CDATA[LB 1 / 0 ]]> 0 0 1 2387 2 2197 ... ... 256 1228

[0119] LUT06

[0120] Secondly, calculate

[0121] (1-i s ′ )+i s ′ *LR 1 / 0 The floating point value range is [0,1], which is divided into 256 intervals at equal intervals, and the nodes in each interval of the floating point number are calculated. And multiply the calculated floating point result by 2 12 , and get the fixed-point mapping table.

[0122] In this embodiment, (1-i s ′ )+i s ′ *LR 1 / 0 Called the first current, the second compensation coefficient lookup table is constructed based on the following steps: for the first current with a value range of [0,1], the value range is equally spaced into 256 nodes; an exponential operation is performed on each interval node, and the exponential operation result is shifted left by 12 bits to obtain the first coefficient corresponding to each node; according to each node and the first coefficient corresponding to each node, a second compensation coefficient lookup table is constructed.

[0123] That is, the value of the first current between 0 and 1 is divided into 256 values, and then an exponential operation is performed. (the range of x is [0,1]), and then the result of the exponential operation is fixed-pointed to 12 bits to obtain the final second compensation coefficient lookup table.

[0124] This embodiment can make the distribution of input data in different ranges be more evenly mapped to the output range through nonlinear transformation, thereby enhancing the dynamic range and color expression of the color channel.

[0125]

[0126] LUT07

[0127] Similarly, the mapping table of G channel and B channel can be obtained as follows:

[0128]

[0129] LUT08

[0130]

[0131] LUT09

[0132] Above All are 12-bit quantized values. According to Tables LUT07, LUT08, and LUT09, we can get the left half of the multiplication in equations (7-1), (7-2), and (7-3).

[0133] Then, calculate This part of the calculation is similar to the above calculation steps, and the constructed third compensation coefficient lookup table is as follows.

[0134]

[0135] LUT10

[0136]

[0137] LUT11

[0138]

[0139] LUT12

[0140] in, All are 12-bit quantized values. According to tables LUT10, LUT11, and LUT12, the right half of the multiplication in equations (7-1), (7-2), and (7-3) can be obtained.

[0141] Figure 4 is a flow chart showing a method for determining a compensation coefficient according to an embodiment of the present invention. Figure 4 As shown, when the first compensation coefficient lookup table, the second compensation coefficient lookup table and the third compensation coefficient lookup table are constructed through the above steps, the process of determining the compensation coefficient of each pixel point based on the actual current and the target current of each pixel point may include the following steps 401 to 406.

[0142] In step 401, for each pixel, the adjustment ratio of the brightness of the grayscale value of the pixel when the contrast changes is obtained from a pre-constructed first compensation coefficient lookup table.

[0143] According to the calculation process of formulas (6-1), (6-2) and (6-3), we are actually comparing the "weighted" brightness ratio of the image at the lowest brightness and the highest brightness. This ratio reflects the relative change of image brightness under different Gamma values ​​(i.e. different contrast conditions). 1 / 0 LG 1 / 0 , LB 1 / 0 It is called the ratio by which brightness is adjusted when contrast changes.

[0144] According to the first compensation coefficient lookup table LUT04, LUT05, LUT06, LR can be obtained 1 / 0 LG 1 / 0 , LB1 / 0 The value of .

[0145] In step 402, a first current for controlling the actual brightness of the pixel is calculated according to the correlation between the target current of the pixel and the adjustment ratio.

[0146] According to formulas (7-1), (7-2) and (7-3), the relationship between the target current of the pixel and the adjustment ratio is (1-i s ′ )+i s ′ *LR 1 / 0 、(1-i s ′ )+i s ′ *LG 1 / 0 、(1-i s ′ )+i s ′ *LB 1 / 0 Based on the above association relationship, when the target current of the pixel point and the adjustment ratio are known, the first current used to control the actual brightness of the pixel point can be calculated.

[0147] In step 403, a first coefficient corresponding to the first current is obtained from a pre-constructed second compensation coefficient lookup table.

[0148] According to the second compensation coefficient lookup tables LUT07, LUT08, and LUT09, when the first current is known, a first coefficient corresponding to the first current can be obtained.

[0149] In step 404, a second current for controlling the actual brightness of the pixel is calculated according to the correlation between the actual current of the pixel and the adjustment ratio.

[0150] According to formulas (7-1), (7-2) and (7-3), the correlation between the actual current of the pixel and the adjustment ratio is (1-i s )+i s *LR 1 / 0 、(1-i s )+i s *LG 1 / 0 、(1-i s )+i s *LB 1 / 0 Based on the above association relationship, when the actual current of the pixel point and the adjustment ratio are known, the second current for controlling the actual brightness of the pixel point can be calculated.

[0151] In step 405, a second coefficient corresponding to the second current is obtained from a pre-constructed third compensation coefficient lookup table.

[0152] According to the third compensation coefficient lookup tables LUT10, LUT11, LUT12, when the second current is known, a second coefficient corresponding to the second current can be obtained.

[0153] In step 406, a compensation coefficient of the pixel point is calculated based on the product of the first coefficient and the second coefficient.

[0154] The multiplication of the first coefficient and the second coefficient is 24 bits. The multiplied number is shifted right by 12 bits and rounded to obtain a 12-bit output.

[0155] It can be seen from steps 401 to 406 that, when the actual current and the target current of each pixel are known, the compensation coefficient of each pixel can be obtained by multi-level search in a pre-constructed set of compensation coefficient lookup tables.

[0156] In this embodiment, in order to improve the accuracy of the compensation coefficient, after determining the compensation coefficient of each pixel point, the compensation coefficient can also be modified using the actual current of the pixel point, specifically including: obtaining the correction coefficient corresponding to the actual current of each pixel point in a pre-constructed correction coefficient lookup table; and using the correction coefficient to correct the compensation coefficient of each pixel point to obtain a corrected compensation coefficient.

[0157] When the global average current and the column current weight corresponding to each pixel are known, the two numbers can be multiplied and shifted right by 12 bits to obtain the actual current of the pixel. The calculated compensation coefficient is corrected for error based on the pre-built lookup table of the actual current and the correction coefficient scale1.

[0158] For example, the correction coefficient lookup table is shown in the following table:

[0159] <![CDATA[i s ]]> scale1 0 2048 1 1905 2 1833 ... ... 256 2048

[0160] In some embodiments, using the correction coefficient to correct the compensation coefficient of each pixel to obtain the corrected compensation coefficient may include: if the compensation coefficient of the pixel is greater than or equal to a preset value, obtaining the difference between the compensation coefficient and the preset value, obtaining the product of the difference and the correction coefficient, calculating the quotient of the product and the preset value, and taking the sum of the quotient and the preset value as the corrected compensation coefficient. If the compensation coefficient of the pixel is less than the preset value, obtaining the difference between the preset value and the compensation coefficient, obtaining the product of the difference and the correction coefficient, and taking the difference between the preset value and the product as the corrected compensation coefficient.

[0161] Specifically, after the compensation coefficient lookup table is consulted to obtain scale1, the compensation coefficient of the pixel point is corrected.

[0162] For example, assuming that the preset value is 2048, taking the compensation coefficient Ratio_R of the R channel as an example, if Ratio_R>=2048, the following calculation is performed:

[0163] ①delta_R=Ratio_R-2048

[0164] ②scale_delta_R=delta_R*scale1 / 2048

[0165] ③Ratio_R=2048+scale_delta_R

[0166] If Ratio_R<2048, then:

[0167] ①delta_R=2048-Ratio_R

[0168] ②scale_delta_R=delta_R*scale1

[0169] ③Ratio_R=2048-scale_delta_R

[0170] After the compensation coefficient is corrected by using the above embodiment, the target grayscale value of each pixel is determined according to the corrected compensation coefficient and grayscale value of each pixel.

[0171] Still taking the compensation of each channel as an example, the target grayscale component corresponding to each channel is calculated according to the following formulas (8-1), (8-2) and (8-3).

[0172] resR = R*ratio_R (8-1)

[0173] resG = G*ratio_G (8-2)

[0174] resB = B*ratio_B (8-3)

[0175] Wherein, resR represents the target grayscale component of the R channel, resG represents the target grayscale component of the G channel, resB represents the target grayscale component of the B channel, ratio_R represents the compensation coefficient after correction of the R channel, ratio_G represents the compensation coefficient after correction of the G channel, and ratio_B represents the compensation coefficient after correction of the B channel.

[0176] After all the above results are shifted right by 11 bits, a 13-bit product is obtained, and the lower 12 bits are intercepted as the target grayscale component.

[0177] Based on the same inventive concept, this embodiment also provides a grayscale compensation device. Figure 5 is a schematic diagram of a grayscale compensation device according to an embodiment of the present invention. Figure 5 The device shown comprises:

[0178] The actual current determination unit 501 is used to determine the actual current of each pixel point according to the global average current of the image to be displayed on the display panel and the column current weight of each pixel point; wherein the global average current is determined according to the sum of the currents of all the pixels, and the current of each pixel point is determined in a pre-constructed first current lookup table according to the grayscale value of the pixel point; and the column current weight is determined according to the average value of the currents of each pixel point in the same column;

[0179] A target current determination unit 502 is used to determine, for each pixel in the image to be displayed, a target current of the pixel in a pre-constructed second current lookup table according to the maximum grayscale component in the three channels of R, G, and B;

[0180] A compensation coefficient determination unit 503, configured to determine a compensation coefficient for each pixel in a pre-constructed set of compensation coefficient lookup tables according to an actual current and a target current of each pixel;

[0181] The compensation unit 504 is used to determine a target grayscale value of each pixel according to the compensation coefficient and the grayscale value of each pixel.

[0182] In some embodiments, the actual current determination unit is specifically used to determine the current of each pixel in a pre-constructed first current lookup table according to the grayscale value of each pixel in the image to be displayed; determine the global average current according to the sum of the currents of all pixels divided by the number of pixels; determine the column average current according to the sum of the currents of all pixels in each column and the number of pixels in the column; determine the column current weight according to a preset power of the column average current, and the column current weights corresponding to each pixel in the same column are the same; and obtain the actual current of each pixel according to the product of the global average current and the column current weight of each pixel.

[0183] In some embodiments, the actual current determination unit is specifically used to obtain, for each pixel in the image to be displayed, a first candidate current corresponding to the upper 8 bits of the 12-bit grayscale value of the pixel from a pre-constructed first current lookup table, and add 1 to the upper 8-bit value to obtain a second candidate current corresponding to the value after the addition operation;

[0184] If the first candidate current is greater than the second candidate current, obtaining a difference between the first candidate current and the second candidate current, performing a bitwise operation on the product of the difference and the lower 4 bits of the 12-bit grayscale value to obtain a first interpolation current, and obtaining a current of the pixel point according to the first candidate current and the first interpolation current;

[0185] If the first candidate current is less than the second candidate current, the difference between the second candidate current and the first candidate current is obtained, and a bit operation is performed on the product of the difference and the lower 4 bits of the 12-bit grayscale value to obtain a second interpolation current, and the current of the pixel point is obtained based on the first candidate current and the second interpolation current.

[0186] In some embodiments, the first current lookup table is constructed based on the following steps: according to the correlation between grayscale values ​​and current values, all values ​​of grayscale values ​​within a preset range are traversed to obtain a first current lookup table; wherein the preset range is [0, 256].

[0187] In some embodiments, the compensation coefficient determination unit is specifically used to obtain, for each pixel, in a pre-constructed first compensation coefficient lookup table, an adjustment ratio of the brightness of the grayscale value of the pixel when the contrast changes; calculate a first current for controlling the actual brightness of the pixel based on a correlation between a target current of the pixel and the adjustment ratio; obtain a first coefficient corresponding to the first current in a pre-constructed second compensation coefficient lookup table; calculate a second current for controlling the actual brightness of the pixel based on a correlation between the actual current of the pixel and the adjustment ratio; obtain a second coefficient corresponding to the second current in a pre-constructed third compensation coefficient lookup table; and calculate the compensation coefficient of the pixel based on the product of the first coefficient and the second coefficient.

[0188] In some embodiments, the second compensation coefficient lookup table is constructed based on the following steps: for a first current with a value range of [0,1], the value range is equally spaced into 256 nodes; an exponential operation is performed on each interval node, and the exponential operation result is shifted left by 12 bits to obtain a first coefficient corresponding to each node; and a second compensation coefficient lookup table is constructed based on each node and the first coefficient corresponding to each node.

[0189] In some embodiments, the compensation coefficient determination unit is also used to obtain a correction coefficient corresponding to the actual current of each pixel point from a pre-constructed correction coefficient lookup table after determining the compensation coefficient of each pixel point; and use the correction coefficient to correct the compensation coefficient of each pixel point to obtain a corrected compensation coefficient.

[0190] In some embodiments, the compensation coefficient determination unit is specifically used to obtain the difference between the compensation coefficient and the preset value, obtain the product of the difference and the correction coefficient, calculate the quotient of the product and the preset value, and use the sum of the quotient and the preset value as the corrected compensation coefficient if the compensation coefficient of the pixel point is greater than or equal to a preset value; if the compensation coefficient of the pixel point is less than the preset value, obtain the difference between the preset value and the compensation coefficient, obtain the product of the difference and the correction coefficient, and use the difference between the preset value and the product as the corrected compensation coefficient.

[0191] This embodiment may also include a display panel, and the display panel in this embodiment may be: electronic paper, mobile phone, tablet computer, television, notebook computer, digital photo frame, navigator, or any other product or component with a display function.

[0192] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A grayscale compensation method, characterized in that: The method comprises: Determine the actual current of each pixel point according to the global average current of the image to be displayed on the display panel and the column current weight of each pixel point; wherein the global average current is determined according to the sum of the currents of all the pixels points, and the current of each pixel point is determined in a pre-constructed first current lookup table according to the grayscale value of the pixel point; and the column current weight is determined according to the average value of the currents of each pixel point in the same column; For each pixel in the image to be displayed, determine the target current of the pixel in a pre-constructed second current lookup table according to the maximum grayscale component in the three channels of R, G, and B; Determine the compensation coefficient of each pixel in a pre-built set of compensation coefficient lookup tables according to the actual current and target current of each pixel; According to the compensation coefficient and grayscale value of each pixel, the target grayscale value of each pixel is determined.

2. The method according to claim 1, characterized in that Before determining the actual current of each pixel, the method further includes: If the image to be displayed is 8 bits, the image to be displayed is converted to 12 bits.

3. The method according to claim 1, characterized in that The method of determining the actual current of each pixel point according to the global average current of the image to be displayed on the display panel and the column current weight of each pixel point includes: Determine the current of each pixel in a pre-constructed first current lookup table according to the grayscale value of each pixel in the image to be displayed; Determine the global average current by dividing the sum of the currents of all pixels by the number of pixels; Determine the column average current according to the sum of the currents of all pixels in each column and the number of pixels in the column; Determining a column current weight according to a preset power of the column average current, wherein the column current weights corresponding to the pixels in the same column are the same; The actual current of each pixel is obtained according to the product of the global average current and the column current weight of each pixel.

4. The method according to claim 3, characterized in that The step of determining the current of each pixel in a pre-constructed first current lookup table according to the grayscale value of each pixel in the image to be displayed includes: For each pixel in the image to be displayed, a first candidate current corresponding to the upper 8 bits of the 12-bit grayscale value of the pixel is obtained from a pre-constructed first current lookup table, and the upper 8-bit value is added by 1 to obtain a second candidate current corresponding to the value after the addition operation; If the first candidate current is greater than the second candidate current, obtaining a difference between the first candidate current and the second candidate current, performing a bitwise operation on the product of the difference and the lower 4 bits of the 12-bit grayscale value to obtain a first interpolation current, and obtaining a current of the pixel point according to the first candidate current and the first interpolation current; If the first candidate current is less than the second candidate current, the difference between the second candidate current and the first candidate current is obtained, and a bit operation is performed on the product of the difference and the lower 4 bits of the 12-bit grayscale value to obtain a second interpolation current, and the current of the pixel point is obtained based on the first candidate current and the second interpolation current.

5. The method according to claim 1, characterized in that The first current lookup table is constructed based on the following steps: According to the correlation between the grayscale value and the current value, all values ​​of the grayscale value within a preset range are traversed to obtain a first current lookup table; wherein the preset range is [0, 256].

6. The method according to claim 1, characterized in that Determining the compensation coefficient of each pixel point in a pre-built set of compensation coefficient lookup tables according to the actual current and the target current of each pixel point includes: For each pixel point, obtaining, in a pre-constructed first compensation coefficient lookup table, an adjustment ratio of the brightness of the grayscale value of the pixel point when the contrast changes; Calculating a first current for controlling an actual brightness of the pixel point according to a correlation between the target current of the pixel point and the adjustment ratio; Obtaining a first coefficient corresponding to the first current from a pre-constructed second compensation coefficient lookup table; Calculating a second current for controlling the actual brightness of the pixel point according to a correlation between the actual current of the pixel point and the adjustment ratio; Obtaining a second coefficient corresponding to the second current from a pre-constructed third compensation coefficient lookup table; A compensation coefficient for the pixel is calculated based on the product of the first coefficient and the second coefficient.

7. The method according to claim 6, characterized in that The second compensation coefficient lookup table is constructed based on the following steps: For a first current whose value range is [0, 1], the value range is divided into 256 nodes at equal intervals; Perform an exponential operation on each interval node, and shift the exponential operation result to the left by 12 bits to obtain the first coefficient corresponding to each node; A second compensation coefficient lookup table is constructed according to each node and the first coefficient corresponding to each node.

8. The method according to claim 1, characterized in that After determining the compensation coefficient of each pixel, the method further includes: Obtaining a correction coefficient corresponding to the actual current of each pixel from a pre-built correction coefficient lookup table; The compensation coefficient of each pixel is corrected using the correction coefficient to obtain a corrected compensation coefficient.

9. The method according to claim 8, characterized in that The method of using the correction coefficient to correct the compensation coefficient of each pixel to obtain the corrected compensation coefficient includes: If the compensation coefficient of the pixel point is greater than or equal to a preset value, obtaining a difference between the compensation coefficient and the preset value, obtaining a product of the difference and the correction coefficient, calculating a quotient of the product and the preset value, and taking the sum of the quotient and the preset value as the corrected compensation coefficient; If the compensation coefficient of the pixel point is less than a preset value, the difference between the preset value and the compensation coefficient is obtained, the product of the difference and the correction coefficient is obtained, and the difference between the preset value and the product is used as the corrected compensation coefficient.

10. A grayscale compensation device, characterized in that: The device comprises: an actual current determination unit, configured to determine the actual current of each pixel point according to the global average current of the image to be displayed on the display panel and the column current weight of each pixel point; wherein the global average current is determined according to the sum of the currents of all the pixels points, the current of each pixel point is determined in a pre-constructed first current lookup table according to the grayscale value of the pixel point; and the column current weight is determined according to the average value of the currents of the pixels points in the same column; a target current determination unit, configured to determine, for each pixel in the image to be displayed, a target current of the pixel in a pre-constructed second current lookup table according to the maximum grayscale component in the three channels R, G, and B; A compensation coefficient determination unit, used to determine the compensation coefficient of each pixel in a set of pre-constructed compensation coefficient lookup tables according to the actual current and the target current of each pixel; The compensation unit is used to determine the target grayscale value of each pixel according to the compensation coefficient and the grayscale value of each pixel.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method described in any one of claims 1 to 9 is implemented.

12. An electronic device, characterized in that: include: processor; a memory for storing processor-executable instructions; The processor is configured to execute the method according to any one of claims 1 to 9.

13. A computer program product comprising a computer program and instructions, characterized in that: When the computer program / instructions are executed by a processor, the method according to any one of claims 1 to 9 is implemented.

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