A method and apparatus for preventing image sticking

Abstract

A method for preventing image sticking. The method includes dividing input frame data into blocks and calculating a representative value for each block, wherein the representative value is calculated for red, green, and blue, each color having an upper limit luminance; increasing a stress value for the block if the representative value is greater than the upper limit luminance and substantially the same as a previously calculated representative value; and reducing the luminance of the block or blurring an image in the block if the stress value is greater than an upper limit stress value. The method achieves prevention of image sticking without occupying a large amount of memory and computation time.

Description

Technical Field

[0001] This invention relates to a method and apparatus for preventing image retention. Background Technology

[0002] When a user displays the same image in the same position on a mobile device's display panel for an extended period, even if the user changes the displayed image, the pattern will still exhibit a slight "image retention" on the display panel. Image retention is one of the problems associated with organic light-emitting diode (OLED) display panels.

[0003] One characteristic of OLEDs is that the pixels in an OLED display degrade according to the magnitude of stress. Stress is the load, such as the cumulative duration of display time, the cumulative value of the product of brightness and display time, etc. Therefore, different OLED degradations will occur depending on the specific image pattern of the application. When displaying a uniform image such as a raster, that particular image pattern can be seen as a shadow.

[0004] One known technique is to blur the edges of windows to make image retention less noticeable. However, window extraction algorithms are insufficient because this technique only works with known window patterns.

[0005] Another technique detects logos by comparing the current frame with the previous frame and then reducing the brightness of the detected logo area. However, this technique requires a large amount of memory to compare the current frame with the previous frame pixel by pixel.

[0006] Current challenges in preventing image persistence include computational costs, large amounts of memory, accuracy, and the aforementioned image degradation. Summary of the Invention

[0007] A method for preventing image persistence is provided to prevent image persistence without consuming a large amount of memory and computing time.

[0008] In a first aspect, a method for preventing image retention is provided, the method comprising: dividing input frame data into blocks and calculating a representative value for each block, wherein the representative value is calculated for red, green and blue, each color having an upper limit brightness; increasing the stress value of the block if the representative value is greater than the upper limit brightness and substantially the same as a previously calculated representative value; and decreasing the brightness of the block or blurring the image in the block if the stress value is greater than the upper limit stress value.

[0009] In one possible implementation of the first aspect, dividing the input frame data into blocks includes: converting the input image data into low-resolution data and dividing the low-resolution data into blocks.

[0010] In one possible implementation of the first aspect, the method further includes: determining whether the cumulative display time of the application is greater than the upper limit time.

[0011] In one possible implementation of the first aspect, the step of reducing the brightness of the block or blurring the image in the block is a step of reducing the brightness of the block or blurring the image in the block during the execution of the application.

[0012] In a second aspect, a computer-readable storage medium containing a program is provided, which, when executed by a processor, causes the processor to perform the method as described in the first aspect or a possible implementation thereof.

[0013] Thirdly, an apparatus for preventing image retention is provided, the apparatus including a memory and a processor, the memory storing a program, the processor executing the program to: divide input frame data into blocks and calculate a representative value for each block, wherein the representative value is calculated for red, green, and blue, each color having an upper limit brightness; if the representative value is greater than the upper limit brightness and substantially the same as a previously calculated representative value, then increase the stress value of the block; and if the stress value is greater than the upper limit stress value, then decrease the brightness of the block or blur the image in the block.

[0014] In one possible implementation of the third aspect, the processor is further configured to: convert the input image data into low-resolution data and divide the low-resolution data into blocks.

[0015] In one possible implementation of the third aspect, the processor is further configured to determine whether the cumulative display time of the application is greater than the upper limit time.

[0016] In one possible implementation of the third aspect, the processor is further configured to: reduce the brightness of the block or blur the image in the block if the stress value is greater than the upper limit stress value, during the execution of the application. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings required for describing the embodiments or the prior art will be briefly introduced below. The drawings described below only show some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0018] Figure 1 An example flowchart of an algorithm for preventing image retention on a display panel is shown;

[0019] Figure 2A A simplified example of image data on the display panel is shown;

[0020] Figure 2B An example of compressed image data is shown;

[0021] Figure 2C An example of image data compressed and divided into grids is shown;

[0022] Figure 3 An example of a detection block is shown;

[0023] Figure 4 This demonstrates how brightness changes over time;

[0024] Figure 5 Examples of images before and after horizontal IIR filtering are shown;

[0025] Figure 6 The brightness of cross sections of the image before and after IIR filtering is shown;

[0026] Figure 7 An example of partially altered grid size is shown;

[0027] Figure 8 Two example images of the game application are shown; and

[0028] Figure 9 This demonstrates an improvement in lifespan in terms of display brightness. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0030] The following explains how to prevent image retention in frame patterns. Mobile devices have a variety of applications. We'll use gaming applications as an example. In many cases, gaming applications display images with high brightness and two types of areas: areas where the image changes frequently and areas where the image hardly changes. For example, some frames and buttons in a gaming application are always located in the same position on the display panel. Figure 2A A simplified example of image data on a display panel is shown. In this example, the images in the upper and lower areas remain almost unchanged, while the image in the middle area changes frequently. Therefore, the almost unchanging areas may cause image retention. Users are not aware of this display pattern when using such applications, but it can appear as image retention when users play these applications for extended periods.

[0031] Figure 1An example flowchart of an algorithm for preventing image retention on a display panel is shown. This algorithm can be implemented by computer software that runs on mobile devices, personal computers, personal digital assistants, gaming devices, and any other device with a display panel.

[0032] Step S1: Calculate and accumulate the display time of each application running on the mobile device.

[0033] Step S2: If the cumulative display time of the application is greater than the predetermined threshold time (i.e., the upper limit), the process proceeds to step S3; otherwise, it returns to step S1.

[0034] The processes in steps S3 to S10 are executed at constant time intervals, for example, every few minutes. Step S3: Compress the input image data, for example, convert the input frame data into low-resolution data. Figure 2B This shows low-resolution data converted from the display image of the game application.

[0035] Step S4: Divide the low-resolution data into a grid, for example, as shown in Figure S4. Figure 2C For the square or rectangular blocks shown, calculate a representative value for each block, and calculate representative values ​​for red, green, and blue. For example, calculate the average pixel value for each color for each block. This pixel value can be the brightness of the color.

[0036] Step S5: Check the representative value for each block. Because LEDs of different colors have different lifespans, each color has a predetermined threshold brightness (i.e., upper limit).

[0037] Step S6: If the representative value of the block is greater than the predetermined threshold brightness, the process proceeds to step S7; otherwise, it returns to step S3.

[0038] Step S7: If the representative value of the block is the same as the previous representative value of the same block (or, if the difference between the representative value of the block and the previous representative value of the same block is less than a predetermined threshold, i.e., the difference is within the range of the predetermined threshold), then the process proceeds to step S8; otherwise, it returns to step S3.

[0039] Step S8: Statistically analyze the stress values, for example, by incrementing and recording the stress values ​​of the block. Also record the color brightness corresponding to the representative values. For example, in... Figure 3 In the shaded blocks, the representative value of the block is the same as the previous representative value of the same block in step S7, and the brightness and stress value of the color are recorded.

[0040] Step S9: If the stress value is greater than the predetermined threshold stress value (i.e., the upper limit), the process proceeds to step S10; otherwise, it returns to step S3.

[0041] Step S10: Change the displayed image to resolve image retention. Reduce the brightness of the block or slightly blur the image in the block based on the recorded color brightness and stress value, as described below. The process returns to step S3 and continues until the application ends.

[0042] In step S10, reducing the brightness can be achieved by using... Figure 4 The infinite impulse response (IIR) filter shown changes its brightness smoothly over time.

[0043] In step S10, the image in the slightly blurred block can be a blurred image through an averaging filter (IIR filter). The brightness of the image boundaries becomes gentler. Figure 5 Examples of images in the horizontal direction before and after IIR filtering are shown. Figure 6 The brightness of cross sections of the image before and after IIR filtering is shown.

[0044] Optionally, in step S4, in order to adopt Figure 7 The icon size shown can partially alter the grid size. That is, the grid size can be adjusted to be small enough to be contained within a stable area of ​​the image. Figure 7 The upper area displays icons, battery percentage, and time. The image in this area is stable. Because the icons, etc., are relatively small, the grid size is also relatively smaller than other areas to ensure that blocks in this area are stable.

[0045] Optionally, an exception procedure may be executed in step S10. Figure 8 Two example images of a game application are shown. The right image has a square area containing multiple icons, a frame area surrounding the square area, a bar chart below the frame area, and a button. The square area includes small icons of different colors and shapes. In the left image, the rectangular blank area in the middle of the square area is the same color as the frame area. The arrangement of the icons changes over time, while the frame area remains unchanged, and the blank area in the left image sometimes appears. In this case, it is assumed that the frame area records stress data, while the blank area does not. If the brightness of the frame area is reduced, the frame area and the blank area will look different. To avoid this, if there is an area that does not record stress data and has a color substantially the same as the area that records stress data, the area that records stress data will not be subjected to brightness reduction and blurring.

[0046] According to embodiments of the present invention, the improvement in lifetime before image persistence is perceived is roughly calculated. The lifetime can be extended by 41% to 15% according to the following formula:

[0047] 1.0–0.9^1.5 = 15% increase in lifespan (acceleration factor = 1.5, brightness changed to 90%)

[0048] 1.0–0.8^1.5 = 28% increase in lifespan (acceleration factor = 1.5, brightness changed to 80%)

[0049] 1.0–0.7^1.5 = 41% increase in lifespan (acceleration factor = 1.5, brightness changed to 70%)

[0050] Figure 9 The diagram also illustrates the improvement in display lifespan in terms of brightness, i.e., the relationship between brightness degradation and display time. The red line represents the case where the method according to the embodiment of the invention is not applied, while the blue, green, and black lines represent the case where the method according to the embodiment of the invention is applied, with the image brightness in the detection block decreasing from 100% to 70%, 38%, and 22%, respectively. If the brightness of the image in the detection block decreases significantly, the brightness degradation slows down.

[0051] According to embodiments of the present invention, the displayed image can be changed naturally, without requiring a large amount of memory, and the processing is very simple. Focusing on the frame and background of the image is very effective in preventing image retention and can reduce power consumption.

[0052] While image persistence prevention and compensation are performed pixel-by-pixel, they offer high accuracy but require enormous memory and computational IP (Intellectual Property Core) sizes, making them difficult to implement on mobile devices such as smartphones. According to embodiments of the present invention, the algorithm is simple and can reduce the required memory, computational costs, and image degradation.

[0053] According to embodiments of the present invention, image retention is effectively prevented without causing image degradation, and no large amount of memory and computation time is required. Image retention of frames and logos can be addressed with a smaller IP size.

[0054] The above disclosures are merely exemplary embodiments of the present invention and are not intended to limit the scope of protection of the present invention. It will be understood by those skilled in the art that all or part of the processes of implementing the foregoing embodiments, as well as equivalent modifications made according to the claims of the present invention, should fall within the scope of the present invention.

Claims

1. A method for preventing image retention, characterized in that, include: The input frame data is divided into blocks and a representative value is calculated for each block. The size of the block is dynamically adjusted according to the size of the image stable region. The representative value is the average of the pixel values ​​of various colors calculated for red, green and blue, with each color having an upper limit brightness. If the representative value is greater than the upper limit brightness and is substantially the same as the previously calculated representative value, then the stress value of the block is increased; and If the stress value is greater than the upper limit stress value, then reduce the brightness of the block or blur the image in the block; Specifically, when a region with unrecorded stress data is detected to have a color that is essentially the same as a region with recorded stress data, the region with recorded stress data will not be subjected to brightness reduction or blurring.

2. The method according to claim 1, characterized in that, Dividing the input frame data into blocks includes: The input image data is converted into low-resolution data, and the low-resolution data is divided into blocks.

3. The method according to claim 1 or 2, characterized in that, Also includes: Determine if the application's cumulative display time exceeds the upper limit.

4. The method according to claim 3, characterized in that, The step of reducing the brightness of the block or blurring the image in the block is a step of reducing the brightness of the block or blurring the image in the block during the execution of the application.

5. A computer-readable storage medium containing a program, characterized in that, When the program is executed by a processor, the program causes the processor to perform the method according to any one of claims 1 to 4.

6. A device for preventing image retention, characterized in that, Includes a memory and a processor, wherein the memory stores a program, and the processor executes the program to: The input frame data is divided into blocks and a representative value is calculated for each block. The size of the block is dynamically adjusted according to the size of the image stable region. The representative value is the average of the pixel values ​​of various colors calculated for red, green and blue, with each color having an upper limit brightness. If the representative value is greater than the upper limit brightness and is substantially the same as the previously calculated representative value, then the stress value of the block is increased; and If the stress value is greater than the upper limit stress value, then reduce the brightness of the block or blur the image in the block; Specifically, when a region with unrecorded stress data is detected to have a color that is essentially the same as a region with recorded stress data, the region with recorded stress data will not be subjected to brightness reduction or blurring.

7. The device according to claim 6, characterized in that, The processor is also used for: The input image data is converted into low-resolution data, and the low-resolution data is divided into blocks.

8. The device according to claim 6 or 7, characterized in that, The processor is also used to determine whether the cumulative display time of the application exceeds the upper limit time.

9. The device according to claim 8, characterized in that, The processor is also used for: If the stress value is greater than the upper limit stress value, then during the execution of the application, the brightness of the block is reduced or the image in the block is blurred.

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