A method for correcting edge brightness of an LED display screen

Abstract

This invention relates to a method for correcting the edge brightness of an LED display screen. The method is as follows: For r columns of pixels at the edge of the display cabinet, a two-dimensional polynomial is fitted using the average grayscale values ​​of pixels in columns s to r, yielding polynomial coefficients; the polynomial coefficients are substituted into the two-dimensional polynomial to obtain the fitted brightness of pixels in columns 1 to s; the fitted brightness of pixels in columns s to r is equal to the average grayscale value of the pixels; the edge pixel trimming ratio is obtained using the fitted brightness and the average grayscale value; finally, the trimming ratio is multiplied by the original correction coefficient to obtain the final pixel correction coefficient. Multiple display cabinets are spliced ​​together to form an LED display screen. The final correction coefficient is applied to the edge pixels of each display cabinet, while the original correction coefficient is applied to the other pixels for display. It can be seen that the bright lines at the seams disappear, and the overall display effect of the LED display screen is uniform.

Description

Technical Field

[0001] This invention belongs to the field of LED display optical acquisition and correction technology, and relates to a method for correcting the edge brightness of an LED display screen. Background Technology

[0002] Due to inherent light emission dispersion and performance degradation, LED chips of the same specifications can emit varying brightness and / or color under the same voltage and current, resulting in uneven brightness and color in LED displays. To improve display uniformity and enhance viewing comfort, LED display calibration technology has been developed. However, after splicing multiple calibrated display cabinets into an LED display, bright lines were found at the splicing points, affecting the display effect. This is because the edge LEDs of the display cabinets only have the brightness of a few surrounding pixels combined, making them dimmer than other areas. Therefore, the calibration coefficient for the edges is larger, resulting in higher edge brightness than the center after calibration. Further correction is needed to adjust the brightness of the edges of the display cabinets to eliminate bright lines at the splicing points and achieve a uniform overall display effect. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for correcting the edge brightness of an LED display screen that can eliminate bright lines at the seams and make the overall display effect of the LED display screen uniform.

[0004] To address the aforementioned technical problems, the LED display edge brightness correction method of the present invention is as follows:

[0005] For the r columns of pixels on the left edge of the display box, collect the gray values ​​of each column of pixels and calculate their average gray values; use the average gray values ​​of the s to r columns of pixels to perform two-dimensional polynomial (1) fitting to obtain the polynomial coefficients p1, p2, p3.

[0006] A m，left =p1*m 2 +p2*m+p3 (m=s~r) (1)

[0007] A m，left The average grayscale value of the m-th column pixel;

[0008] Calculate the fitted brightness of each column of pixels on the left edge according to formula (2);

[0009]

[0010] I m，left The fitted brightness of the m-th column pixel;

[0011] Calculate the trimming ratio for each column of pixels on the left edge:

[0012] B m，left =I m，left / A m，left (3)

[0013] B m，left The trimming ratio for the m-th pixel on the left edge;

[0014] Similarly, the trimming ratio of each column or row of pixels on the right, top, and bottom edges is obtained;

[0015] The final correction coefficient for a pixel is obtained by multiplying the trimming ratio of each column or row of pixels on the edge with the original correction coefficient of the corresponding pixel.

[0016] Furthermore, suppose the display box has y rows and x columns, and the maximum value of y and x is N, then r is 2 to 4 times N / 32.

[0017] Furthermore, s = round(N / 32).

[0018] The original correction coefficients of each pixel in the display cabinet are obtained by pre-calibrating the display cabinet.

[0019] For the r columns of pixels on the left edge of the display cabinet, the grayscale value of each column of pixels is collected as follows: one column of pixels is lit up at a time, and at the same time, the camera is used to take a picture of the lit column of pixels to obtain the grayscale value of each column of pixels.

[0020] Furthermore, the camera is fixed on a horizontal guide rail, and one column of pixels is lit up from the edge to the inside each time. When the next column of pixels is lit up, the camera moves to the right on the guide rail by a distance equal to one column spacing.

[0021] Furthermore, each column of pixels can be illuminated using a full-light method.

[0022] Furthermore, each column of pixels can be illuminated by using an alternating row pixel illumination method.

[0023] Beneficial effects:

[0024] Multiple display cabinets are spliced ​​together to form an LED display screen. A final correction coefficient is applied to the edge pixels of each display cabinet, while the original correction coefficient is applied to the other pixels for display. It can be seen that the bright lines at the splicing seams disappear, and the overall display effect of the LED display screen is uniform. Attached Figure Description

[0025] Figure 1 This is a schematic diagram showing the sequential acquisition of the brightness of each column of pixels on the left edge of the display cabinet.

[0026] Figure 2 This is a schematic diagram showing the sequential acquisition of the brightness of each column of pixels on the upper edge of the display cabinet.

[0027] Figure 3This is a schematic diagram showing the pixel-alternating columns displayed on the upper and lower edges of the display box.

[0028] Figure 4 , Figure 5 These are images taken when the first and 36th columns of pixels on the display panel are lit.

[0029] Figure 6 , Figure 7 These are images taken when the first and 36th rows of pixels on the display panel are lit.

[0030] Figure 8a , Figure 8b , Figure 8c These are the actual brightness, the fitted brightness, and the final corrected brightness when the pixels on the edge of the display cabinet display the three primary colors of red, green, and blue. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present invention are shown in the drawings, not the entire structure.

[0032] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0033] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0034] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0035] Example 1: An LED display cabinet with a pixel pitch of 1.19mm and 288 rows and 256 columns of pixels.

[0036] Step 1: Calibrate the display cabinets to obtain the calibration coefficient F(i,j) for each pixel, where i = 1–288 and j = 1–256; i is the row coordinate of the pixel, and j is the column coordinate of the pixel. F(i,j) includes the original calibration coefficients for the three primary colors: red, green, and blue. A bright line exists at the seam of a spliced ​​LED display using multiple calibrated display cabinets.

[0037] Step 2: Select the 36 columns of pixels on the left edge of the display cabinet that were calibrated in Step 1. Illuminate one column of pixels at a time, moving from the edge to the inside, while simultaneously taking 36 pictures. Figure 4 As shown; adjust the camera's focus and exposure time before shooting to ensure the captured image has clear pixels and is not overexposed; if the camera's low resolution makes pixel segmentation impossible, an interlaced pixel lighting method is used; in this embodiment, an interlaced 4-row lighting method is used. Figure 1 As shown, when illuminating the next column of pixels, the camera moves one column spacing to the right on the guide rail, aligning the camera lens with the normal direction of the next column of pixels, ensuring that all illuminated pixels are contained within the camera's field of view. Similar to the above method, 36 columns of pixels on the right edge of the display cabinet, calibrated in step one, are selected. One column of pixels is illuminated at a time from the edge to the inside, while the camera simultaneously captures images of the display cabinet, resulting in 36 images. The images captured by the camera are shown below. Figure 5 .

[0038] Select 36 rows of pixels along the top edge of the display cabinet after the calibration in step one. Illuminate one row of pixels at a time, moving from the edge to the inside, while simultaneously taking 36 pictures of the display cabinet. Figure 6 As shown; adjust the camera's focus and exposure time before shooting to ensure the captured image pixels are clear and not overexposed; if the low camera resolution makes the pixels indivisible, a method of lighting every other column of pixels is used, in this embodiment, a method of lighting every four columns is used. Figure 2As shown, when illuminating the next column of pixels, the camera moves downwards on the guide rail, aligning the camera lens with the normal direction of that row of pixels, ensuring that all illuminated pixels are contained within the camera's field of view. Similar to the above method, 36 rows of pixels along the lower edge of the display cabinet, calibrated in step one, are selected. One row of pixels is illuminated at a time, moving from the edge to the inside, while the camera simultaneously captures images of the display cabinet, resulting in 36 images. The images captured by the camera are shown below. Figure 7 .

[0039] If the edge pixel images of the three primary colors (red, green, and blue) are collected in the same way as in step two, a total of 36×4×3=432 images will be obtained.

[0040] Step 3: Calculate the average grayscale value of each row or column of pixels at the edge. It can be seen that the average grayscale value of pixels near the edge is significantly larger; the captured image also shows that the brightness of pixels near the edge is significantly higher; taking the left edge pixels as an example, the average grayscale value A of the pixels in columns 1 to 8 is... 1，left ~A 8，left This is particularly evident, therefore edge brightness adjustment is necessary. This invention utilizes the average grayscale value A of pixels in columns 9 to 36. 9，left ~A 36，left The following formula is used for two-dimensional polynomial fitting:

[0041] A m，left =p1*m 2 +p2*m+p3 (m=9~36) (1)

[0042] A m，left Let p1 be the average gray value of the m-th column of pixels; p1, p2, and p3 are obtained by fitting polynomial coefficients using the above formula; p1, p2, and p3 are then substituted into the two-dimensional polynomial to obtain the fitted brightness of the pixels in columns 1 to 8; the fitted brightness of the pixels in columns 9 to 36 is equal to the average gray value of the pixels in that column.

[0043]

[0044] I m，left The fitted brightness of the m-th column pixel;

[0045] Calculate the trimming ratio for each column of pixels on the left edge:

[0046] B m，left =I m，left / A m，left , m=1~36 (3)

[0047] B m，left The trimming ratio for the m-th pixel on the left edge;

[0048] Similarly, the trimming ratio B of the m-th row on the upper edge can be obtained. m，upThe trimming ratio of the mth row of the lower edge is B. m,down , and the trimming ratio B of the mth row on the right edge m,right .

[0049] The original correction coefficients of each pixel in columns 1 to 36 (or rows) are corrected by using the trimming ratio of the four edges. The trimming ratio is then multiplied by the original correction coefficient of each pixel to obtain the final correction coefficient of each pixel.

[0050]

[0051] F(i,j) is the original correction coefficient of the pixel in the i-th row and j-th column, and P(i,j) is the final correction coefficient of the pixel in the i-th row and j-th column.

[0052] After loading P(i,j) (P(i,j) includes the correction coefficients for the three primary colors of red, green, and blue), the edge 36 lines were collected again under the same experimental conditions to verify the feasibility of the method. For example, the test data from the left edge was used. Figure 8a , 8b As shown in Figure 8c, A represents the actual brightness, B represents the fitted brightness, and C represents the brightness after edge correction. The data shows a significant improvement in edge brightness. When multiple displays are assembled, the bright lines at the seams disappear, resulting in a more uniform overall display effect.

[0053] This invention is not limited to the above embodiments. The number of columns or rows of edge pixels is not strictly limited. The more suitable selection range for r is 2 to 4 times N / 32, and the more suitable selection range for s is round (N / 32), where round means rounding.

Claims

1. A method for correcting edge brightness of an LED display screen, characterized in that... The method is as follows: For the r columns of pixels on the left edge of the display box, collect the gray values ​​of each column of pixels and calculate their average gray values; use the average gray values ​​of the s to r columns of pixels to perform two-dimensional polynomial (1) fitting to obtain the polynomial coefficients p1, p2, p3. A m，left =p1*m 2 +p2*m+p3 (m=s~r) (1) A m，left The average grayscale value of the m-th column pixel; Calculate the fitted brightness of each column of pixels on the left edge according to formula (2); I m，left The fitted brightness of the m-th column pixel; Calculate the trimming ratio for each column of pixels on the left edge: B m，left =I m，left / A m，left (3) B m，left The trimming ratio for the m-th pixel on the left edge; Similarly, the trimming ratio of each column or row of pixels on the right, top, and bottom edges is obtained; The final correction coefficient for a pixel is obtained by multiplying the trimming ratio of each column or row of pixels on the edge with the original correction coefficient of the corresponding pixel.

2. The LED display screen edge brightness correction method according to claim 1, characterized in that: If the display box has y rows and x columns, and the maximum value of y and x is N, then r is 2 to 4 times N / 32.

3. The LED display screen edge brightness correction method according to claim 2, characterized in that: s = round(N / 32).

4. The LED display screen edge brightness correction method according to claim 1, characterized in that: The original correction coefficients of each pixel in the display cabinet are obtained by pre-calibrating the display cabinet.

5. The LED display screen edge brightness correction method according to claim 1, characterized in that: For the r columns of pixels on the left edge of the display cabinet, the grayscale value of each column of pixels is collected as follows: one column of pixels is lit up at a time, and at the same time, the camera is used to take a picture of the lit column of pixels to obtain the grayscale value of each column of pixels.

6. The LED display screen edge brightness correction method according to claim 1, characterized in that: Fix the camera on a horizontal guide rail, and light up one column of pixels from the edge to the inside each time. When lighting up the next column of pixels, the camera moves to the right on the guide rail by a distance equal to one column spacing.

7. The LED display screen edge brightness correction method according to claim 1, characterized in that: Each column of pixels is illuminated using a full-light method.

8. The LED display screen edge brightness correction method according to claim 1, characterized in that: Each column of pixels is illuminated using an alternating row pixel illumination method.

Images