TWI715334B - Data compression method and storage device having compensation values generated by the same - Google Patents

Abstract

A data compression method capable of local demura on a display screen of a display panel, wherein the display screen is divided into a plurality of screen blocks. The method includes: capturing mura data of the plurality of screen blocks of the display screen; calculating mura compensation values of the plurality of screen blocks of the display screen according to the captured mura data; calculating mura compensation value variation degrees of each screen block of the display screen according to the mura compensation values of the plurality of the screen blocks of the display screen; selecting a compression mode for each screen block of the display screen according to the magnitude of the mura compensation value variation degree of each screen block of the display screen; and compressing the mura compensation values of each screen block of the display screen with a corresponding compression mode so as to obtain compressed mura compensation values of each screen block of the display picture.

Description

Data compression method and storage device with compensation value generated by the method

The present invention relates to a data compression method, in particular to a data compression method that locally compensates for uneven brightness of a display screen and a storage device storing the compressed Mura compensation value generated by the method.

For general thin-film display panels (such as LCD, OLED, etc.), process problems often cause uneven brightness (Mura) during the display of the panel image, resulting in stripe marks, block marks, sand marks, or It is a trace of any combination of the aforementioned stripes, blocks and sand. Therefore, in order to improve the display image quality and yield of the panel, it is necessary to add Demura or Demura or Demura to the Display driving IC. The function of compensating uneven brightness.

As shown in Fig. 1 is a general technology framework for compensation of brightness unevenness (Demura), which includes the following processing procedures: (A) Use a camera to capture the brightness unevenness of the entire display screen of a display panel 11 (Mura) Data 12; (B) Calculate the brightness unevenness (Mura) compensation value 13 of the display screen according to the captured brightness unevenness data 12 of the display screen; (C) Data the Mura compensation value 13 of the display screen Compression coding to obtain the compressed brightness unevenness (Mura) compensation value of the display picture 14; (D) The compressed Mura compensation value of the display picture 14 is stored in a storage device 15 such as a flash memory; and (E) the display driving integrated circuit 16 loads the compressed Mura compensation value of the display screen 14 from the storage device 15 to its static state at startup Random access memory (Static Random Access Memory, SRAM) 161, and decompress it to restore the display screen Mura compensation value 13', and then use the display screen Mura compensation value 13' to the display screen of the display panel 11. Perform brightness compensation (Demura).

It can be seen that the core technology of the existing Demura technology architecture is the data compression processing and calculation of the Mura compensation value. If a low data compression ratio is used, sufficient memory (flash memory and static random access memory) must be available. To store the uniformity compensation data of the display screen (Mura compensation value of the compressed display screen). On the contrary, the use of high data compression ratio can reduce the memory (flash memory and static random access memory) capacity, but if the data Too much compression will result in a poor uniformity compensation effect. Therefore, how to trade-off between the memory capacity and the uniformity compensation effect is really a problem to be solved.

However, in the existing Demura technology, the data compression processing of the Mura compensation value is to process the Mura compensation value of the entire display screen with the same data compression ratio. Therefore, as the panel resolution increases, the Mura data and the Mura compensation value are generated. The substantial increase in the number not only leads to an increase in the required memory capacity, but also increases the cost of the application system and the display driver integrated circuit, and makes it difficult to strike a balance between the memory capacity and the uniformity compensation effect.

Therefore, the conventional data compression method for compensating for uneven brightness still has many shortcomings, and it is difficult to meet the requirements of today's high-resolution display devices, and there is still a need for improvement.

The purpose of the present invention is mainly to provide a data compression method that can partially compensate for the uneven brightness of the display screen, which uses different compression ratios for data compression according to the Mura area and type of the different display screens, while taking into account the reduction of the required memory capacity. And the uniformity compensation effect, to effectively solve the lack of the aforementioned conventional technology.

According to one feature of the present invention, the present invention provides a data compression method that can partially compensate for uneven brightness of a display screen. The display screen is divided into a plurality of screen blocks. The method includes the steps: (A) capture a majority of the display screen The brightness unevenness (Mura) data of a screen block; (B) According to the captured Mura data, calculate the brightness unevenness (Mura) compensation value of a plurality of screen blocks of the display screen; (C) According to The Mura compensation value of a plurality of screen blocks of the display screen is calculated, and the brightness unevenness (Mura) compensation value variation degree of each screen block of the display screen is calculated; (D) According to the difference of each screen block of the display screen Mura compensation value variation degree, select the data compression mode of each screen block of the display screen; and (E) compress the Mura compensation value of each screen block of the display screen in the corresponding data compression mode, The compressed brightness uneven (Mura) compensation value of each frame of the display frame is obtained.

According to another feature of the present invention, the present invention provides a storage device that stores the compressed Mura compensation value generated by the aforementioned local de-brightness data compression method.

The above summary and the following detailed description are exemplary in nature, and are intended to further illustrate the scope of the patent application of the present invention. Other objectives and advantages of the present invention will be described in the following description and drawings.

11: Display panel

12: Uneven brightness data

13,13’: Brightness uneven compensation value

14: Compressed brightness uneven compensation value

15: storage device

16: Display driver integrated circuit

161: Static random access memory

S201, S203, S205, S207, S209: steps

31: Display screen

311: Pixel

33: Screen block

351: Uneven brightness data

353: Brightness uneven compensation value

355: Variation degree of brightness uneven compensation value

357: compressed mode

359: Compressed brightness uneven compensation value

37: storage device

39: Display driver integrated circuit

391: Static random access memory

Figure 1 schematically shows the technical architecture of general compensation for brightness unevenness (Demura).

2 is a flowchart of a data compression method for locally compensating uneven brightness of a display screen according to the present invention.

3(A) to 3(F) schematically show the execution state of the data compression method for partially compensating for uneven brightness of the display screen of the present invention.

In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not to limit the present invention.

Figure 2 is a flowchart of the data compression method for partially compensating for uneven brightness of the display screen of the present invention, and Figures 3(A) to 3(F) schematically show the data compression method for partially compensating for uneven brightness of the display screen of the present invention Execution status.

Please also refer to Figures 2 and 3(A) to 3(F). The data compression method of the present invention for partially compensating the uneven brightness of the display screen is to remove the uneven brightness or compensate the brightness (Demura) of the display screen of the display panel. Data compression, where, as shown in FIG. 3(A), the display screen 31 includes a plurality of pixels 311 arranged in a matrix, for example, and the display screen 31 is divided into a plurality of non-overlapping screen blocks 33, each The picture block 33 includes a plurality of pixels 311. Furthermore, each pixel 311 described above has at least one sub-pixel, that is, the display screen 31 correspondingly has at least one sub-pixel channel. In the following description of this embodiment, each pixel 311 includes a red ( R) sub-pixel, one green (G) sub-pixel, and one blue (B) sub-pixel, so the display screen 31 corresponds to a red (R) sub-pixel channel, one green There are three sub-pixel channels such as a color (G) sub-pixel channel and a blue (B) sub-pixel channel, but this is only an example, and the present invention is not limited thereto.

First, in step S201, for each pixel channel of the display screen 31, the brightness unevenness (Mura) data 351 presented by the majority of the screen blocks 33 of the display screen 31 captured by a camera, such as Figure 3(B) schematically shows that a pixel 311 includes a red (R) sub-pixel, a green (G) sub-pixel, and a blue (B) sub-pixel, and the display screen 31 corresponds to Take a red (R) sub-pixel channel, a green (G) sub-pixel channel, and a blue (B) sub-pixel channel as an example; secondly, in step S203, for each pixel of the display screen 31 Channel, according to the captured Mura data of the majority of the screen blocks 33 of the display screen 31, calculate the brightness unevenness (Mura) compensation value 353 of the majority of the screen blocks 33 of the display screen 31, as shown in Figure 3(C) As shown in the schematic display, a pixel 311 includes a red (R) sub-pixel, a green (G) sub-pixel, and a blue (B) sub-pixel, and the display screen 31 corresponds to a red (R) sub-pixel. ) Sub-pixel channel, one green (G) sub-pixel channel, and one blue (B) sub-pixel channel as examples.

Next, in step S205, according to the Mura compensation value 353 obtained in step S203, for each pixel channel of the display screen 31, calculate the brightness unevenness (Mura) compensation value variation of each screen block 33 of the display screen 31 The degree 355, shown schematically in FIG. 3(D), is a pixel 311 including a red (R) sub-pixel, a green (G) sub-pixel, and a blue (B) sub-pixel, and The display screen 31 corresponds to a red (R) sub-pixel channel, a green (G) sub-pixel channel, and a blue (B) sub-pixel channel as an example. In this step, the red (R) ) Mura compensation value variation 355 of each frame 33 of the sub-pixel channel, green (G) sub-pixel channel and blue (B) sub-pixel channel:

其中，畫面區塊33之大小為M畫素x N畫素(M及N皆為大於1之正整數)，R、G、B分別代表紅色、綠色、藍色次畫素，Com_avg代表畫面區塊33中Mura補償值之平均，Com_i代表畫面區塊33中第i個畫素的補償值，D_avg代表畫面區塊33的平均變異，亦即為求得之畫面區塊33的Mura補償值變異程度355。

Among them, the size of the picture block 33 is M pixels x N pixels (M and N are both positive integers greater than 1), R, G, and B represent red, green, and blue sub-pixels, respectively, and Com _avg represents the picture The average of the Mura compensation value in block 33, Com _i represents the compensation value of the i-th pixel in the picture block 33, and D _avg represents the average variation of the picture block 33, which is the calculated Mura of the picture block 33 The degree of variation of the compensation value is 355.

According to the above calculation formula, for each pixel channel of the display screen 31, step S205 is to first calculate the average value of the Mura compensation value in a screen block 33, and then calculate each Mura compensation value of the screen block 33 And the average value of this Mura compensation value The difference value between the two, and the difference values are averaged as the Mura compensation value variation degree 355 of the frame block 33 in the sub-pixel channel.

Then, in step S207, according to the Mura compensation value variation degree 355 obtained in the foregoing step S205, for each pixel channel of the display screen 31, the foregoing Mura compensation value variation degree 355 is compared with at least one variation threshold value, and accordingly Select the compression mode 357 of each picture block 33 of the display picture 31, as shown in FIG. 3(E), with one pixel 311 including one red (R) sub-pixel and one green (G) sub-pixel And a blue (B) sub-pixel, the display screen 31 correspondingly has a red (R) sub-pixel channel, a green (G) sub-pixel channel, and a blue (B) sub-pixel channel, and at least one The variation threshold includes three variation thresholds (TH1, TH2, TH3, where TH1>TH2>TH3) as an example. In this step, the following judgment formula is used to determine the red (R) sub-pixel channel and the green (G) sub-pixel channel respectively. The compression mode 357 of each frame 33 of the pixel channel and the blue (B) sub-pixel channel:

其中，R、G、B分別代表紅色、綠色、藍色次畫素，TH1、TH2、TH3為變異臨界值，“Compression mode=1”代表壓縮比(compression ratio)=4/3(1.33X),bpp(bits per pixel)=6(bits)，“Compression mode=2”代表壓縮比(compression ratio)=8/3(2.66X),bpp(bits per pixel)=3(bits)，“Compression mode=3”代表壓縮比(compression ratio)=16/3(5.33X),bpp(bits per pixel)=1.5(bits)，“Compression mode=4”代表壓縮比(compression ratio)=32/3(10.66X),bpp(bits per pixel)=0.75(bits)。

Among them, R, G, and B represent red, green, and blue sub-pixels, TH1, TH2, and TH3 are the critical values of variation, and "Compression mode=1" represents the compression ratio=4/3 (1.33X) ,bpp(bits per pixel)=6(bits), "Compression mode=2" represents the compression ratio (compression ratio)=8/3(2.66X), bpp(bits per pixel)=3(bits), "Compression mode =3" represents compression ratio=16/3(5.33X), bpp(bits per pixel)=1.5(bits), "Compression mode=4" represents compression ratio=32/3(10.66) X),bpp(bits per pixel)=0.75(bits).

It can be seen from the above judgment formula that for each pixel channel of the display screen 31, the compression ratio of the compression mode 357 selected in step S207 for a screen block 33 of the display screen 31 is inversely proportional to that of the screen block 33 Mura compensation value variation degree 355, that is, when the Mura compensation value variation degree 355 of a picture block 33 is larger, it means that the difference between the Mura compensation values changes greatly. It is not advisable to compress the Mura compensation value with a high compression ratio to avoid data Distorted and cannot be restored correctly, so select the compression mode 357 with a smaller compression ratio. When the degree of variation 355 of the Mura compensation value of a picture block 33 is smaller, it means that the difference between the Mura compensation values is small. It is suitable to compress the Mura compensation value with a high compression ratio to greatly reduce the amount of data, so choose a larger compression ratio Compression mode 357.

Finally, in step S209, according to the compression mode 357 obtained in step S207, for each pixel channel of the display screen 31, the Mura compensation value 353 of each frame 33 of the display screen 31 is set to the corresponding compression mode 357 Perform compression to obtain the compressed brightness unevenness (Mura) compensation value 359 of each picture block 33, as shown in FIG. 3(F), and then obtain the compressed Mura compensation for the display picture 31 of each pixel channel The compressed Mura compensation value for the display screen 31 of all sub-pixel channels is stored in a storage device 37, such as a flash memory, for subsequent reading by the display drive integrated circuit 39 The static random access memory 391 is used for decompression to compensate for uneven brightness of the display panel.

As can be seen from the above description, since the brightness unevenness of the red, green, and blue sub-pixel channels of each pixel on the display panel is different, the present invention is aimed at the red, green, and blue sub-pixels. Each picture block in the channel selects a different compression mode, and compresses the corresponding magnification. And further in order to make the sum of the compressed brightness uneven compensation values of all the screen blocks of the display screen smaller than a preset memory capacity value, so as to ensure that the amount of compressed data can be stored in the storage device 37 (or static random access In the memory 391), that is, Rcom_size+Gcom_size+Bcom_size<=Demura Ram Size, where Rcom_size is the size of all compressed mura compensation values of the red sub-pixel channel in the entire display screen, and Gcom_size is the entire display screen The size of all compressed Mura compensation values of the green sub-pixel channel, Bcom_size is the size of all compressed Mura compensation values of the blue sub-pixel channel in the entire display screen, Demura Ram Size is the storage device 37 (or static random access memory) The size of body 391), the present invention can appropriately adjust the mutation threshold The size of (TH1, TH2, TH3) meets the requirements for the size of all compressed Mura compensation values of the red, green, and blue sub-pixel channels. Among them, due to adjusting all the compression of the red, green, and blue sub-pixel channels The magnitude of the Mura compensation value will affect the Demura effect of the red, green, and blue sub-pixel channels and the Demura effect of the grayscale. For grayscale, the uniformity of green affects the uniformity of the grayscale the most. Therefore, in Demura In actual operation, the gray-scale uniformity is the top priority, and Gcom_size>Rcom_size>Bcom_size is given to ensure a good gray-scale Demura effect.

The above-mentioned embodiments are merely examples for the convenience of description, and the scope of rights claimed in the present invention should be subject to the scope of the patent application, rather than limited to the above-mentioned embodiments.

S201, S203, S205, S207, S209: steps

Claims (13)

A data compression method for partially compensating for uneven brightness of a display screen. The display screen is divided into a plurality of screen blocks. The method includes the steps of: (A) capturing the display of the plurality of screen blocks of the display screen (B) Based on the captured brightness uneven data, calculate the brightness uneven compensation value of the multiple screen blocks of the display screen; (C) According to the multiple screens of the display screen The brightness unevenness compensation value of the block, calculate the brightness unevenness compensation value variation degree of each screen block of the display screen; (D) according to the brightness unevenness compensation value of each screen block of the display screen For the magnitude of the degree of variation, select the data compression mode of each screen block of the display screen; and (E) use the brightness unevenness compensation value of each screen block of the display screen to correspond to the data compression mode Compression is performed to obtain the compressed brightness uneven compensation value of each picture block of the display picture. According to the data compression method described in item 1 of the scope of patent application, the display screen includes a plurality of pixels, and each pixel has at least one sub-pixel, and the display screen correspondingly has at least one sub-pixel channel. For the data compression method described in item 2 of the scope of patent application, step (A) is to capture the brightness unevenness data of the plurality of screen blocks of the display screen for each pixel channel of the display screen . For the data compression method described in item 2 of the scope of patent application, wherein, step (B) is to calculate the brightness unevenness compensation value of the plurality of screen blocks of the display screen for each pixel channel of the display screen . The data compression method described in item 2 of the scope of patent application, wherein, step (C) is for each pixel channel of the display screen, calculating the brightness unevenness compensation value of each screen block of the display screen The degree of variation. The data compression method described in item 2 of the scope of patent application, wherein, step (D) is to select the data compression mode of each screen block of the display screen for each pixel channel of the display screen. For the data compression method described in item 2 of the scope of patent application, wherein, step (E) is for each pixel channel of the display screen, the brightness unevenness compensation value of each screen block of the display screen Compression is performed in the corresponding data compression mode to obtain the compressed brightness uneven compensation value of each screen block of the display screen. For the data compression method described in item 1 of the scope of patent application, in step (C), the average value of the brightness unevenness compensation value in a screen block is first calculated, and then each of the screen blocks is calculated The difference value between the brightness unevenness compensation value and the average value of the brightness unevenness compensation value, and the difference values are averaged as the degree of variation of the brightness unevenness compensation value of the screen block. The data compression method described in the first item of the scope of patent application, wherein, in step (D), for a screen block of the display screen, the compression ratio of the selected compression mode is inversely proportional to the screen block The magnitude of the degree of variation in the compensation value for uneven brightness. For the data compression method described in item 2 of the scope of patent application, in step (D), the magnitude of the variation degree of the brightness unevenness compensation value of each screen block of the display screen is combined with at least one variation threshold The value is compared to select the compression mode of each screen block of the display screen. The data compression method described in item 10 of the scope of patent application, wherein, in step (E), the sum of the compressed brightness unevenness compensation values of all screen blocks of the display screen is less than a preset memory capacity value . The data compression method described in item 11 of the scope of patent application, wherein each pixel includes a red sub-pixel, a green sub-pixel and a blue sub-pixel, and the display screen corresponds to a red sub-pixel Pixel channel, a green sub-pixel channel and a blue sub-pixel channel, the at least one variation threshold is adjusted to make Gcom_size>Rcom_size>Bcom_size, where Rcom_size is all compression of the red sub-pixel channel in the display The size of the brightness unevenness compensation value, Gcom_size is the size of all compressed brightness unevenness compensation values of the green sub-pixel channel in the display screen, Bcom_size is the compression brightness unevenness compensation value of all the blue sub-pixel channels in the display screen the size of. A storage device stores the compressed brightness unevenness compensation value generated by the data compression method described in item 1 of the scope of patent application.

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