A local dimming optimization method and system for Mini-LED backlight display

Abstract

This invention provides a method for optimizing local dimming for Mini-LED backlit displays. This method divides a single-frame image into fixed-size blocks and optimizes dimming based on the brightness of the image blocks, ambient light levels, viewing distance, and the contrast sensitivity characteristics of the human visual system. After brightness compensation, the image blocks are subjected to edge detection. If clogging artifacts are present, secondary brightness compensation is performed on the image blocks based on the contrast sensitivity curve peaks and edge detection results, and the image blocks are then reassembled into a complete image. Otherwise, the image blocks are directly reassembled into a complete image. This method, which comprehensively considers viewing conditions and the characteristics of the human visual system, divides the image into fixed blocks for line-by-line scanning, improving backlight dimming accuracy and reducing energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of display devices, and in particular to a local dimming optimization method for a Mini-LED backlight display. Background Art

[0002] Traditional display devices have some shortcomings in dimming. For example, excessive dimming may cause contrast loss or blocking artifacts, while insufficient dimming affects the viewing experience. Therefore, an efficient local dimming algorithm is needed to optimize the performance and effect of the display. Summary of the Invention

[0003] Purpose of the Invention: This invention provides a method and system for optimizing local dimming for Mini-LED backlit displays. This method optimizes dimming based on the brightness of image blocks, ambient light intensity, viewing distance, and the contrast sensitivity of the human visual system to maximize display quality and minimize energy consumption. Furthermore, the algorithm accounts for and optimizes the potential for blocking artifacts caused by locally dimmed image blocks.

[0004] Technical solution: This method first divides the image frame into blocks of fixed size and evaluates the brightness and contrast sensitivity of each block separately. By analyzing the spatial frequency and image width of the image block and combining it with the characteristics of the human visual system under specific viewing conditions, the contrast sensitivity level of the image block is evaluated, that is, the degree to which the human eye perceives specific spatial frequency changes in the image is determined. Then, the contrast of the image block is combined to obtain its contrast sensitivity value, and the corresponding backlight value is calculated to minimize contrast loss and brightness loss. After brightness compensation is performed on the image block, edge detection is performed on it. If there is a blocking artifact, the image block is subjected to secondary brightness compensation based on the peak value of the contrast sensitivity curve and the edge detection result, and the image block is re-merged into a complete image. Otherwise, the image block is directly re-merged into a complete image.

[0005] A local dimming optimization method for a Mini-LED backlight display comprises the following steps:

[0006] Step 1: Divide the image frame into image blocks of fixed size;

[0007] Step 2: Calculate the contrast sensitivity of the image block;

[0008] Step 3: Calculate the contrast sensitivity of the image block according to the contrast sensitivity of the image block;

[0009] Step 4: Calculate the backlight setting value of the image block according to the contrast sensitivity of the image block;

[0010] Step 5: Calculate the pixel difference between each edge of the image block and the adjacent image blocks to perform edge detection to determine whether the image block has a blockage artifact; if not, proceed to step 8; otherwise, proceed to step 6;

[0011] Step 6: Calculate the secondary brightness compensation amount based on the maximum value of the contrast sensitivity of the image block and the pixel difference;

[0012] Step 7: Calculate the secondary compensation backlight setting value according to the secondary brightness compensation amount and the backlight setting value;

[0013] Step 8: Merge the image patches back into the complete image.

[0014] Preferably, the image is divided into m*n regions corresponding to the number of backlight partitions, where m and n are constants.

[0015] Preferably, the contrast sensitivity curve function CSF of the image block with respect to the image spatial frequency x is:

[0016]

[0017] Where W is the image width; L is the average brightness of the image block; Ls is the ambient light brightness; D is the viewing distance; A is the magnification factor related to the average brightness L of the image block, the ambient light brightness Ls and the viewing distance D; B is a constant magnification factor.

[0018] Preferably,

[0019] Preferably, the contrast sensitivity Sen of the image block is obtained by the following formula:

[0020]

[0021] Where CR is the contrast of the image block, and CSF(x) is the contrast sensitivity curve function of the image block with respect to the image spatial frequency x. When the image is fixed, its spatial frequency x is fixed, and CSF is also constant at a certain viewing distance and ambient light, then Sen is also fixed.

[0022] Preferably, after obtaining the contrast sensitivity value Sen, the corresponding backlight setting value is calculated by the following formula:

[0023] Backlight=a*Sen b *L c

[0024] Where a, b, and c are constant compensation coefficients, and L is the average brightness of the image block.

[0025] Preferably, edge detection is performed to determine whether there is a blockage artifact in the image block by calculating the pixel difference between each edge of the image block and the adjacent block using the following formula:

[0026]

[0027] Where i = 1, 2, 3, 4 correspond to the left, right, top, and bottom edges of the image block, respectively, ∑p' edge is the number of pixels on the edge of adjacent blocks, ∑p edge is the number of pixels at the edge of the detection block, n is the number of pixels on a specific side; when the Edge of the four edges sum The maximum value in If the value is greater than the detection threshold, it is determined that there is a blockage artifact.

[0028] Preferably, the secondary brightness compensation amount B com Calculated by the following formula:

[0029]

[0030] CSF max is the maximum value in the contrast sensitivity curve, α is the constant compensation coefficient, It is the maximum value of the pixel difference between each edge of the image block and the adjacent blocks.

[0031] Preferably, the secondary compensation backlight setting value is Backlight+B com , Backlight is the backlight setting value, B com is the secondary brightness compensation amount.

[0032] The present invention also provides a local dimming optimization system for a Mini-LED backlight display, comprising:

[0033] An image frame segmentation module is used to segment the image frame into blocks of fixed size;

[0034] A contrast sensitivity calculation module, used to calculate the contrast sensitivity of an image block;

[0035] a contrast sensitivity calculation module, configured to calculate the contrast sensitivity of an image block according to the contrast sensitivity of the image block;

[0036] a backlight setting value calculation module, configured to calculate a backlight setting value of an image block according to the contrast sensitivity of the image block;

[0037] A clogging artifact judgment module is used to calculate the pixel difference between each edge of an image block and an adjacent image block to perform edge detection and determine whether the image block has a clogging artifact;

[0038] A secondary brightness compensation amount calculation module is used to calculate the secondary brightness compensation amount according to the contrast sensitivity of the image block and the maximum value of the pixel difference;

[0039] A secondary compensation backlight setting value calculation module is used to calculate the secondary compensation backlight setting value according to the secondary brightness compensation amount and the backlight setting value;

[0040] An image block merging module, used to merge image blocks into a complete image;

[0041] To achieve the local dimming optimization method of the Mini-LED backlight display.

[0042] Beneficial Effects: This invention performs local dimming based on the characteristics of image blocks, taking into account the sensitivity of the human visual system and the influence of viewing conditions. Compared with existing dimming methods, this method reduces the loss of brightness and contrast within the human eye's perceptible range, improves dimming accuracy, and reduces energy consumption. Furthermore, this invention provides a method for compensating for blocking artifacts caused by dimming of localized image blocks. Compared with existing methods, this method focuses solely on brightness differences at the edges of image blocks, reducing image computing resource consumption.

[0043] This invention innovatively proposes a method for calculating contrast sensitivity (CSF), incorporating the human eye's observation characteristics into the dimming process. Sen and Backlight are calculated sequentially from CSF to obtain the backlight setting value Backlight for a single image. During the image merging process, CSF is used to optimize the clogging artifacts and obtain the backlight secondary compensation value B. com . Finally Backlight+B com This is the final optimized setting value of the image block brightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Schematic diagram of the calculation process of the present invention. DETAILED DESCRIPTION

[0045] The present invention will be further explained below with reference to the accompanying drawings.

[0046] like Figure 1 As shown in the figure, the image is first segmented into fixed-size blocks based on the backlight zones. The image blocks are 120 x 120 pixels, and the image is segmented into 32 x 18 regions. Since the block size is fixed, the edge position is fixed, eliminating the need for additional algorithms to determine the block edge position, improving work efficiency.

[0047] The contrast sensitivity curve is used to analyze the spatial frequency and image width of the image block, and combined with the characteristics of the human visual system under specific viewing conditions, the contrast sensitivity level of the image block is evaluated. The contrast sensitivity curve function (CSF) for the image spatial frequency x is:

[0048]

[0049] Where W is the image width, cm; L is the average brightness of the image block, lm; Ls is the ambient light brightness, lm; and D is the viewing distance, cm. A is the magnification factor related to the average brightness L of the image block, the ambient light brightness Ls, and the viewing distance D:

[0050]

[0051] B is a constant magnification factor, which is 0.06 in this example.

[0052] Once the CSF curve is determined, the area below the curve is the sensitive area of the human visual system, and the area above the curve is the insensitive area of the human visual system. When the image spatial frequency is constant, the contrast CR of the image block is combined to obtain the sensitivity Sen observed by the human eye.

[0053]

[0054] In this example, CR can be calculated as follows:

[0055]

[0056] Among them, L max 、L min are the maximum and minimum brightness of the image block, lm respectively.

[0057] After obtaining its contrast sensitivity value, the corresponding backlight setting value is calculated using the following formula:

[0058] Backlight=a*Sen b *L c

[0059] Where a, b, and c are constant compensation coefficients. In this example, a = 1.1, b = 0.2, and c = 0.6. After setting the backlight according to Backlight, the pixel difference between each edge of the image block and the adjacent block is calculated by the following formula to perform edge detection to determine whether the image block has blockage artifacts:

[0060]

[0061] Where i = 1, 2, 3, 4 correspond to the left, right, top, and bottom edges of the image block, respectively, ∑p' edge is the number of pixels on the edge of adjacent blocks, ∑p edge is the number of pixels at the edge of the detection block, and n is the number of pixels on a specific side. sum The maximum value in If it is greater than the detection threshold of 20, it is determined that there is a blockage artifact. Otherwise, the image blocks are directly merged. The secondary brightness compensation amount B is calculated by the following formula com :

[0062]

[0063] CSF max is the maximum value of the contrast sensitivity curve, α is a constant compensation coefficient, which is 0.75 in this example. The final backlight setting value is (Backlight+B com ). After brightness compensation is completed, the image blocks are merged.

Claims

1. A local dimming optimization method for a Mini-LED backlight display, characterized in that: The steps include: Step 1: Divide the image frame into image blocks of fixed size; Step 2: Calculate the contrast sensitivity of the image block; Step 3: Calculate the contrast sensitivity of the image block according to the contrast sensitivity of the image block; Step 4: Calculate the backlight setting value of the image block according to the contrast sensitivity of the image block; Step 5: Calculate the pixel difference between each edge of the image block and the adjacent image blocks to perform edge detection to determine whether the image block has a blockage artifact; if not, proceed to step 8; otherwise, proceed to step 6; Step 6: Calculate the secondary brightness compensation amount based on the maximum value of the contrast sensitivity of the image block and the pixel difference; Step 7: Calculate the secondary compensation backlight setting value according to the secondary brightness compensation amount and the backlight setting value; Step 8: Merge the image patches back into the complete image.

2. The local dimming optimization method for a Mini-LED backlight display according to claim 1, characterized in that: The image is divided into m*n regions corresponding to the number of backlight partitions, where m and n are constants.

3. The local dimming optimization method for a Mini-LED backlight display according to claim 1, wherein: The contrast sensitivity curve function CSF of the image block with respect to the image spatial frequency x is: Where W is the image width; L is the average brightness of the image block; Ls is the ambient light brightness; D is the viewing distance; A is the magnification factor related to the average brightness L of the image block, the ambient light brightness Ls and the viewing distance D; B is a constant magnification factor.

4. The local dimming optimization method for a Mini-LED backlight display according to claim 3, wherein:

5. The local dimming optimization method for a Mini-LED backlight display according to claim 1, wherein: The contrast sensitivity Sen of the image block is obtained by the following formula: Where CR is the contrast of the image block, and CSF(x) is the contrast sensitivity curve function of the image block with respect to the image spatial frequency x.

6. The local dimming optimization method for a Mini-LED backlight display according to claim 1, wherein: After obtaining its contrast sensitivity value Sen, the corresponding backlight setting value is calculated using the following formula: Backlight=a*Sen b *L c Where a, b, and c are constant compensation coefficients, and L is the average brightness of the image block.

7. The local dimming optimization method for a Mini-LED backlight display according to claim 1, wherein: The pixel difference between each edge of the image block and the adjacent block is calculated by the following formula to perform edge detection to determine whether the image block has blockage artifacts: Where i = 1, 2, 3, 4 correspond to the left, right, top, and bottom edges of the image block, respectively, ∑p' edge is the number of pixels on the edge of adjacent blocks, ∑p edge is the number of pixels on the edge of the detection block, n is the number of pixels on the edge; when the four edges of the Edge sum The maximum value in If the value is greater than the detection threshold, it is determined that there is a blockage artifact.

8. The local dimming optimization method for a Mini-LED backlight display according to claim 1, wherein: Secondary brightness compensation amount B com Calculated by the following formula: CSF max is the maximum value in the contrast sensitivity curve, α is the constant compensation coefficient, It is the maximum value of the pixel difference between each edge of the image block and the adjacent blocks.

9. The local dimming optimization method for a Mini-LED backlight display according to claim 1, wherein: The secondary compensation backlight setting value is Backlight+B com , Backlight is the backlight setting value, B com is the secondary brightness compensation amount.

10. A local dimming optimization system for a Mini-LED backlight display, characterized in that: include: An image frame segmentation module is used to segment the image frame into blocks of fixed size; A contrast sensitivity calculation module, used to calculate the contrast sensitivity of an image block; a contrast sensitivity calculation module, configured to calculate the contrast sensitivity of an image block according to the contrast sensitivity of the image block; a backlight setting value calculation module, configured to calculate a backlight setting value of an image block according to the contrast sensitivity of the image block; A clogging artifact judgment module is used to calculate the pixel difference between each edge of an image block and an adjacent image block to perform edge detection and determine whether the image block has a clogging artifact; A secondary brightness compensation amount calculation module is used to calculate the secondary brightness compensation amount according to the contrast sensitivity of the image block and the maximum value of the pixel difference; A secondary compensation backlight setting value calculation module is used to calculate the secondary compensation backlight setting value according to the secondary brightness compensation amount and the backlight setting value; An image block merging module, used to merge image blocks into a complete image; To implement the local dimming optimization method of the Mini-LED backlight display described in any one of claims 1-9.

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