Gray jitter compensation method and system applied to LED display
By using a grayscale jitter compensation method and adjusting the grayscale display with a counter, the problems of insufficient refresh rate and uneven brightness of LED displays under low gray conditions are solved, achieving higher brightness adjustment accuracy and refresh rate, and improving the display effect.
Patent Information
- Application Number
- CN202511479429.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-16
- Publication Date
- 2026-02-10
AI Technical Summary
In existing technologies, LED displays have insufficient refresh rates under low gray conditions, resulting in dimness and poor linearity in low gray conditions, as well as problems such as speckling and uneven brightness.
The grayscale jitter compensation method is adopted, which utilizes the principle of visual persistence. By setting counters and Ncounter, X grayscale values are compensated to adjust the grayscale display and ensure that the brightness and refresh rate of each frame reach or exceed the human eye frequency, thus achieving smooth processing of grayscale values.
It improves the issues of dim brightness and linearity in low grayscale displays, enhances the precision of brightness adjustment and refresh rate, reduces brightness jumps and flickering, and improves the viewing experience.
Smart Images
Figure CN121506027A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of LED display, more particularly, to an LED display gray scale dithering compensation method and system. BACKGROUND
[0002] In the development of LED display driving chip technology, the PWM (Pulse Width Modulation) technical solution is widely used to improve the refresh rate. The PWM technology increases the overall refresh rate of the LED display screen by dividing the on time of a group of data into multiple time periods, which improves the low refresh rate of the built-in PWM algorithm, but also brings some problems.
[0003] As shown in FIG. 1, in the LED display technology, in order to improve the refresh rate (the refresh rate is defined as the number of times of picture light and dark changes per second, and the refresh rate = frame rate * scattering group number), it is often necessary to scatter a frame of display data into multiple groups, for example Figure 1 As shown, the gray value data 4096 is scattered into 23 groups, 4096 / 8 = 512, and the gray value displayed by each group is 512. The display is scattered from one group of 4096 into eight groups, and the number of light and dark times is increased by 8 times. The high level represents the LED light, and the low level represents the LED off. In this way, the display refresh rate is increased by 8 times. High display refresh rate is beneficial to reduce display flicker and glare, and provides a more comfortable viewing experience.
[0004] However, in the low gray condition, as shown in FIG. 2, if the frame rate is 60, in the condition of displaying a gray value of only 1, although it is scattered into 8 groups, because there is only one gray value, only one group has a high level (lighting), and the other 7 groups do not, so the refresh rate is 60*1 = 60Hz. When the gray value is 2, as shown in FIG. 3, two groups have gray data, and the refresh rate is 60*2 = 120Hz. Only when the display gray value is greater than or equal to 8, the refresh rate is maximum, which is 60*8 = 480Hz. It can be seen that in the low gray condition, the refresh rate is low.
[0005] In addition, in the low gray condition, due to the difference of the chip, the coupling of the chip and other problems, the actual channel on time is lower than the set PWM on time. As shown in Figure 4 The actual on time is <1 gray value (one clock cycle). The on time difference between chip 1 and chip 2 (the time difference of high level), and this difference causes low gray dark and poor low gray linearity when the human eye watches.
[0006] Firstly, the on time under low gray scale is very short, and if these gray scales are scattered into multiple time periods, the single gray value in each time period may not be able to be displayed completely, resulting in the phenomenon of low gray mura. This is because the brightness of low gray scale is low, and it needs longer on time to be displayed. After the on time of low gray scale is divided into multiple time periods, the brightness of each time period is very short, and it may not be able to fully present the brightness of low gray scale, thereby mura appears.
[0007] Secondly, the brightness under low gray scale may be dark, and the linearity of low gray scale is poor. Since the on time of low gray scale is very short, the LED display screen may not be able to reach a lower brightness level, resulting in dark display of low gray scale.
[0008] In addition, since the brightness changes rapidly in each time period, the linearity of low gray scale may be poor, that is, the relationship between brightness and input gray value is not linear, which may lead to unsatisfactory display effect. Especially in the case of high clock frequency during gray scale display, the above problems are particularly obvious. Under high frequency, the brightness changes more rapidly in each time period, and the display problem of low gray scale is more prominent. SUMMARY
[0009] The purpose of the present application is to provide a method and system for compensating for LED display gray scale dithering.
[0010] The present application aims to solve the problems of insufficient low gray refresh rate and poor low gray effect of the multi-line scanning constant current source chip in the prior art.
[0011] Compared with the prior art, the technical scheme and beneficial effects of the present application are as follows:
[0012] The first aspect of the present application discloses a method for compensating for LED display gray scale dithering, comprising: S1, setting M frames as a cycle, setting two counters, counter and Ncounter, and compensating for X gray scale values; S2, setting the initial value of the counter counter as 0, and taking the counting value of the counter counter as the serial number of the frame; S3, judging whether all input gray scale values are 0; if all input gray scale values are not 0, judging whether X is greater than the counting value of the counter Ncounter; if all input gray scale values are 0, the displayed gray scale is equal to the input gray scale and returning to step S2; S4, if X is greater than the counting value of the counter Ncounter, the displayed gray scale is equal to the input gray scale plus 1, and the counting value of the counter counter is added by 1; if X is not greater than the counting value of the counter Ncounter, the displayed gray scale is equal to the input gray scale, and the counting value of the counter counter is added by 1; S5, obtaining the next frame gray scale value, and judging whether the counting value of the counter counter is equal to M; if the counting value of the counter counter is equal to M, returning to step S2; if the counting value of the counter counter is not equal to M, returning to step S3.
[0013] The second aspect of the present application discloses a system for compensating for LED display gray scale dithering, which is used for executing the method steps in any one of the first aspect of the present application.
[0014] The present application has the following advantages:
[0015] The present application utilizes visual persistence (when we look at an object or a scene, our visual system will still maintain a visual impression for a period of time after the object or the scene disappears), in this process, the transmission and processing of visual information need a certain time. When we look at an object, the brain will integrate and smooth the continuous visual information to generate a continuous visual perception. Because the frequency of LED display is greater than the frequency of human eye watching, the display gray scale value of a specific frame is compensated for with the clock as the minimum increase unit, so that the overall brightness and refresh rate effect is compensated. Moreover, the frequency of LED display is higher than the frequency of human eye, so the effect of the compensated gray scale perceived by the human eye is the increase of brightness and the improvement of refresh rate.
[0016] Through the method for compensating for gray scale dithering, in the case of low gray display, the problems of low gray dark and poor low gray linearity can be improved, and the delicate degree of PWM signal change is increased, and the precision of brightness adjustment is improved. BRIEF DESCRIPTION OF DRAWINGS
[0017] Figure 1 It is the first schematic diagram of background art.
[0018] Figure 2is a second schematic diagram of the background art.
[0019] Figure 3 is a third schematic diagram of the background art.
[0020] Figure 4 is a fourth schematic diagram of the background art.
[0021] Figure 5 is a step schematic diagram of an LED display gray scale dithering compensation method provided by an embodiment of the present application.
[0022] Figure 6 is a flow schematic diagram of an LED display gray scale dithering compensation method provided by an embodiment of the present application.
[0023] Figure 7 is a schematic diagram of brightness compensation for 1 gray scale of a first frame with 8 frames as a cycle provided by an embodiment of the present application.
[0024] Figure 8 is a schematic diagram of brightness compensation for 1 gray scale with equivalent effect with 8 frames as a cycle provided by an embodiment of the present application.
[0025] Figure 9 is a schematic diagram of brightness compensation for 1 gray scale of a first frame and a fifth frame with 8 frames as a cycle provided by an embodiment of the present application.
[0026] Figure 10 is a schematic diagram of the relationship between the number of compensated gray scales and the increased brightness and the increased refresh rate with 8 frames as a cycle provided by an embodiment of the present application. DETAILED DESCRIPTION
[0027] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.
[0028] In the description of the present application, the terms “first” and “second” are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with “first” and “second” can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of “a plurality of” is two or more, unless otherwise specifically limited.
[0029] Referring to Figure 5 and Figure 6 The first aspect of the present application is shown in the figure, which provides a method for compensating for LED display gray dithering, comprising:
[0030] S1, setting M frames as a cycle, setting two counters counter and Ncounter, and compensating for X gray values;
[0031] S2, setting the initial value of the counter counter as 0, and taking the counting value of the counter counter as the serial number of the frame;
[0032] S3, judging whether all input gray values are 0; if all input gray values are not 0, judging whether X is greater than the counting value of the counter Ncounter; if all input gray values are 0, the displayed gray is equal to the input gray and returning to step S2;
[0033] S4, if X is greater than the counting value of the counter Ncounter, the displayed gray is equal to the input gray plus 1, and the counting value of the counter counter is added by 1; if X is not greater than the counting value of the counter Ncounter, the displayed gray is equal to the input gray, and the counting value of the counter counter is added by 1;
[0034] S5, obtaining the next frame gray value, and judging whether the counting value of the counter counter is equal to M; if the counting value of the counter counter is equal to M, returning to step S2; if the counting value of the counter counter is not equal to M, returning to step S3.
[0035] The setting of M frames as a cycle makes the minimum display precision 1 / M.
[0036] The value of the counter Ncounter is equal to the value of the counter counter data high-low bit symmetry exchange; the counter counter={counter[2],counter[1],counter[0]}, and {counter[2],counter[1],counter[0]} is transformed into {counter[0],counter[1],counter[2]}, so the counter Ncounter={counter[0],counter[1],counter[2]}.
[0037] The counter counter and Ncounter are both 3-bit binary counters.
[0038] The second aspect of the present application provides a LED display gray dithering compensation system for executing the method steps of any one of the first aspect of the present application.
[0039] As shown in Figure 7 , 1 gray level is compensated in the 1st frame of every 8 frames, and the effect of the 1 compensated gray level in each frame is that the overall brightness and refresh rate of 8 frames are increased by 1 / 8, and the brightness effect is equivalent to displaying 1+1 / 8 gray levels in each frame, and the equivalent effect is shown in Figure 8 . It can be seen that the display resolution is changed from 1 gray level to 1 / 8 gray level, the change of the PWM signal is increased in detail, and the accuracy of the brightness adjustment is improved.
[0040] Similarly, if the brightness of 1 gray level is increased in the 1st frame and the 5th frame of 8 frames, as shown in Figure 9 , the overall brightness and refresh rate are increased by 2 / 8. The relationship between the 8-frame 3-bit compensation gray level and the increased brightness and refresh rate is shown in Figure 10 . It can be seen that the overall brightness can be adjusted with 1 / 8 gray level accuracy, and the detail is 8 times that of the previous one. If 8 frames are taken as a cycle, the display resolution is increased by 3 bits. Similarly, if 16 frames are taken as a cycle, the display resolution is increased by 4 bits, and the minimum adjustment resolution is 1 / 16. This small time offset compensation can make the LED adjust more accurately, and the brightness change of the LED display screen is more detailed and accurate. Through small time offset compensation, the brightness change of the PWM signal can be more smooth and continuous, reducing the brightness jump and flicker phenomenon, improving the low gray effect, and improving the adjustable linearity. This can improve the viewing experience of the LED display screen and reduce visual fatigue.
[0041] The principle of the LED display gray dithering compensation method and system provided by the present application is as follows:
[0042] For example, 8 frames are taken as a cycle, and the flow is as shown in Figure 5 and Figure 6As shown. Setting 8 frames as a loop, the minimum precision is 1 / 8. Two 3-bit binary counters, counter and Ncounter, are set, and X grayscale values are compensated. The value of counter Ncounter is equal to the value of the counter counter data with the high and low bits swapped in the middle. Counter counter = {counter[2], counter[1], counter[0]}. {counter[2], counter[1], counter[0] is transformed into {counter[0], counter[1], counter[2]}, so Ncounter = {counter[0], counter[1], counter[2]}. For example, if the value of the 3-bit binary counter counter is 3'b001, the value of the 3-bit binary counter Ncounter obtained by the symmetrical swap in the middle is 3'b100. If the value of counter is 3'b110, after the symmetrical swap in the middle, the value of Ncounter is 3'b011. This makes the compensation display interval time symmetrical, such as Figure 8 When compensating for two grayscale values, the compensated grayscale is added in frames 1 and 5. Initially, the 3-bit binary counter is set to 0, and the counter count value is used as the frame number. It checks if all input grayscale values are 0. If they are 0, the counter is reset to 0. If the input grayscale is not 0, it checks if X is greater than the 3-bit binary counter N. If X is greater than N, the displayed grayscale is equal to the input grayscale value plus 1 as compensation. If X is not greater than N, the displayed grayscale is the original input grayscale. After the first frame is displayed, the counter count is incremented by 1, and Ncounter equals the new {counter[0], counter[1], counter[2]}. It is then determined whether the grayscale values of all inputs in the second frame are equal to 0. If they are 0, the counter is reset to 0. If the grayscale values of the inputs are not 0, it is determined whether X is greater than the new Ncounter. If X is greater than Ncounter, the displayed grayscale value is equal to the input grayscale value plus 1 as compensation. If X is not greater than Ncounter, the displayed grayscale value is the input grayscale value, and the counter count is incremented by 1. This process is repeated until the counter reaches 8, at which point the counter is reset to 0 and the count restarts.
[0043] The above embodiments are only used to explain the technical solutions of the present invention and are not intended to limit it. Those skilled in the art should understand that any modifications and equivalent substitutions that do not depart from the spirit and scope of the present invention should fall within the protection scope of the claims of the present invention.
Claims
1. A method for grayscale jitter compensation in LED displays, characterized in that, include: S1, set M frames to loop, set two counters counter and Ncounter, and compensate for X grayscale values; S2, set the initial value of the counter to 0, and use the count value of the counter as the sequence number of the frame; S3, determine if all input grayscale values are 0; if all input grayscale values are not 0, determine if X is greater than the count value of counter Ncounter; if all input grayscale values are 0, the displayed grayscale is equal to the input grayscale and return to step S2. S4, if X is greater than the count value of counter Ncounter, the displayed grayscale is equal to the input grayscale plus 1, and the count value of counter is incremented by 1; if X is not greater than the count value of counter Ncounter, the displayed grayscale is equal to the input grayscale, and the count value of counter is incremented by 1. S5, obtain the grayscale value of the next frame, and determine whether the count value of the counter is equal to M; if the count value of the counter is equal to M, return to step S2; if the count value of the counter is not equal to M, return to step S3.
2. The grayscale jitter compensation method for LED displays according to claim 1, characterized in that, If the M-frames are set to loop, then the minimum display resolution is: .
3. The grayscale jitter compensation method for LED displays according to claim 1, characterized in that, The value of the counter Ncounter is equal to the value of the counter data with the high and low bits swapped symmetrically in the middle; The counter counter = {counter[2], counter[1], counter[0]}, and {counter[2], counter[1], counter[0]} is transformed into {counter[0], counter[1], counter[2]}, then the counter Ncounter = {counter[0], counter[1], counter[2]}.
4. The method for grayscale jitter compensation in LED displays according to claim 1, characterized in that, Both the counter and Ncounter are 3-bit binary counters.
5. A grayscale jitter compensation system for LED displays, characterized in that, Used to perform the method steps of any one of claims 1-4.