A method for correcting LED display screen

Abstract

The present invention relates to a method for correcting an LED display screen, which divides the display screen into n independent areas; a camera is set at the C position, and the camera lens is respectively aimed at the center point of each area to obtain an image of each area; the light spot of each area image is positioned; the brightness of the LED pixel points in each area is respectively corrected according to the sum of the brightness values ​​of each camera pixel in the light spot, and the brightness correction of the entire display screen is completed. The present invention is suitable for correcting large-size ultra-wide or ultra-high spliced ​​LED display screens. When viewed at the "C position", any position of the screen has a good display effect.

Description

Technical Field

[0001] The invention belongs to the technical field of LED display optical collection and correction, and relates to a LED display screen correction method. Background Art

[0002] Since LED display screens are usually calibrated in the normal direction, in special occasions such as command centers, dispatch centers, monitoring centers, and display centers, when the screen size is super large, super wide, and the side viewing angle is super large, the display screen directly facing the "C position" has a good effect, while the display screens on both sides are at a certain angle to the best viewing position, resulting in uneven display screens. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a correction method for a large-size spliced ​​LED display screen with uniform display effect when viewed from a "C position".

[0004] In order to solve the above technical problems, the LED display screen correction method of the present invention adopts the following two technical solutions.

[0005] Technical Solution 1

[0006] The display screen is divided into n independent areas; the camera is set at the C position, and the camera lens is aimed at the center point of each area to obtain the image of each area; the light spot of each area image is located; according to the sum of the brightness values ​​of each camera pixel in the light spot, the brightness of the LED pixel points in each area is corrected to complete the brightness correction of the entire display screen.

[0007] Technical Solution 2

[0008] The display screen is divided into n areas, and the borders of adjacent areas overlap; the camera is set at the C position, and the camera lens is aimed at the center point of each area to obtain the image of each area; the light spot of each area image is located; according to the sum of the brightness values ​​of each camera pixel in each light spot, the brightness of the LED pixel points in each area is corrected to obtain the final correction coefficient of the LED pixel points in the non-overlapping area and the two primary correction coefficients of the LED pixel points in the overlapping area;

[0009] For any overlapping area L k For the LED pixel in the ith column or row, let the number of columns or rows in the previous area be p, and the primary correction coefficient be a. p ; In the next area, the number of columns or rows is q, and the primary correction coefficient is b q ; Calculate the secondary correction coefficient of the LED pixel according to the following formula

[0010]

[0011] Where h is the total number of columns or rows of LED pixels in the overlapping area;

[0012] The secondary correction coefficient of each LED pixel in the overlapping area is the final correction coefficient corresponding to each LED pixel; the final correction coefficient is used to correct the brightness value of all LED pixels to complete the brightness correction of the entire display screen.

[0013] The width of the overlapping area is at least the width of two display modules.

[0014] Furthermore, the camera is arranged on an electrically controlled turntable at position C, and the optical axis of the camera lens intersects the display screen at point O perpendicularly; according to the vertical distance between the camera lens and the display screen, and the distance between point O and the center point of each area, the angles between the lines connecting the camera lens and the center point of each area and the normal line of the corresponding area are calculated respectively, and according to the angle calculation results, the electrically controlled turntable is controlled to rotate the corresponding angle so that the camera lens is directed toward the center point of each area to shoot and obtain images of each area.

[0015] Furthermore, each light spot is positioned using the centroid method.

[0016] Further, the method of positioning each light spot using the centroid method is as follows:

[0017] First, mathematical morphology is performed on the images of each region. Then, the threshold of the images after mathematical morphology processing is calculated using the Otsu method. The camera pixel values ​​greater than the threshold are set to 1, and the camera pixel values ​​less than the threshold are set to 0, and the images are converted into binarized images. The light spot outline in the binarized image is obtained, and then the light spot outline is processed into a circular light spot. The center coordinates of the light spot (x c ,y c ):

[0018]

[0019]

[0020]

[0021] Where: r is the diameter of the circular spot; The coordinates are (x i ,y i ), and W is the sum of the brightness values ​​of the camera pixels in the circular spot.

[0022] Beneficial effects:

[0023] By controlling the electric control turntable to rotate to a corresponding angle based on the calculated result of the angle between the line between the camera lens and the center point of each area and the normal line of the corresponding area, the camera lens can be accurately aligned with the center point of each area, thereby ensuring the accuracy of the final correction result.

[0024] The light spots collected from the left and right sides due to the side viewing angle of the super-large display screen are severely distorted by trapezoids, so that the light spot segmentation method based on the conventional standard horizontal and vertical rows and columns cannot correctly segment the light spots. The present invention jumps out of the concept of light spot segmentation by rows and columns, and uses the centroid method to determine the center coordinates of the light spots. The light spot positioning is based on the positioning of isolated light spots, and is not restricted to the arrangement relationship of the light spots, and does not care whether the light spots are arranged in standard horizontal and vertical rows and columns. In this way, any deformation of the light spot arrangement, including trapezoids or other special shapes, does not affect the correct positioning and segmentation of the light spots.

[0025] By regional fusion of LED pixels in overlapping areas, the display effects of adjacent areas can be made consistent. The calibrated LED large-size ultra-wide or ultra-high spliced ​​display screen can be viewed from the "C position", and any position on the screen has the best viewing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the brightness collection method of a traditional large-size LED display.

[0027] Figure 2 It is a schematic diagram of the brightness collection method of a large-size LED display screen according to Example 1 of the present invention.

[0028] Figure 3 , Figure 4 , Figure 5 , Figure 6 These are the display effects of areas 1, 2, 4, and 5.

[0029] Figure 7 It is the binary image of region 1.

[0030] Figure 8 This is a schematic diagram of the center of gravity method for positioning the light spot.

[0031] Fig. 9 Schematic diagram of the overlapping area of ​​the display screen. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0033] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood in specific circumstances.

[0034] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" or "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0035] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplified operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0036] like Figure 1 As shown in the figure, the calibration of the traditional large-size spliced ​​LED display cannot be completed through a one-time acquisition and calibration due to the limited resolution of the camera. Therefore, the display is usually divided into n areas. Taking n=5 as an example, the camera is placed in the normal direction of each area for acquisition and calibration. The best viewing position of area 1 is A, the best viewing position of area 2 is B, the best viewing position of area 3 is C, the best viewing position of area 4 is D, and the best viewing position of area 5 is E.

[0037] like Figure 2 As shown in Figure 1, when in the C position, only area 3 has the best display effect, while areas 1, 2, 4, and 5 are at a certain angle to the C position. The angle α between area 1 and the normal line when viewed from the C position 1 The display effect, when viewing area 2 from position C, is at an angle α with the normal 2 The display effect, when viewing area 4 from position C, is at an angle θ with the normal line. 2The display effect, the area No. 5 viewed from the C position is the angle θ with the normal 1 display effect.

[0038] In view of the above situation, the present invention proposes a method for correcting an LED display screen, so that the display effect of a large-size spliced ​​LED display screen viewed at the "C position" is uniform.

[0039] Example 1

[0040] The LED display screen correction method of the present invention is as follows:

[0041] Step 1: Divide the display screen into n independent areas; here, take a display screen with an extra-large horizontal size, n=5, as an example, place the camera at the C position, and capture images of each area.

[0042] When shooting, the camera lens can be manually aimed at the center point of each area to obtain the image of each area. However, the intersection of the optical axis of the camera lens and the display screen in this method may deviate from the center point of each area, resulting in the final calibration result being inaccurate. Therefore, the present invention preferably uses the following method for shooting.

[0043] The camera is placed on the electric control turntable at position C, with the optical axis of the lens perpendicularly intersecting the display screen at point O (i.e., the center point of area 3); according to the vertical distance between the camera lens and the display screen, and the distance between point O and the center points of areas 1, 2, 4, and 5, the angle α between the line connecting position C and the center points of areas 1, 2, 4, and 5 and the normal of each area is calculated respectively. 1 , α 2 ,θ 2 ,θ 1 .

[0044] Use the camera to shoot area 3 to obtain the image of the area; then control the electric control turntable to rotate through angle α 1 Point the camera lens toward the center of area 1 to capture the image of the area. The captured image is as follows: Figure 3 As shown; control the electric control turntable to rotate through an angle α 1 -α 2 Point the camera lens toward the center of area 2 to capture the image of the area. The captured image is as follows: Figure 4 As shown; control the electric control turntable to rotate through an angle α 2 +θ 2 The camera lens is pointed toward the center point of area 4 to obtain the image value of the area. The displayed screen is as follows Figure 5 As shown; control the electric control turntable to rotate through θ 1 -θ 2 The camera lens is pointed toward the center of area 5 to obtain the image of the area. The image captured at this time is as follows: Figure 6As shown; when shooting, make sure that all LED pixels in each area are within the camera's field of view.

[0045] The capturing of the images of the respective regions may be performed in any order and is not limited to the above order.

[0046] Step 2: Use the centroid method to locate each light spot. The specific method is as follows:

[0047] First, mathematical morphology is performed on the images of each region. Then, the threshold of the images after mathematical morphology processing is calculated using the Otsu method. The camera pixel values ​​greater than the threshold are set to 1, and the camera pixel values ​​less than the threshold are set to 0, and the images are converted into binary images (the binary image of region 1 is shown in Figure 1). Figure 7 As shown); get the spot outline in the binary image, and then process the spot outline into a circular spot, the center coordinates of the circle are the center coordinates of the circular spot. Then, each circular spot is regarded as an object, its brightness integral value is regarded as the total gravity of the object, each camera pixel brightness value in the circular spot is regarded as a component force of a small object, and the camera pixel coordinates where each camera pixel brightness value is located are regarded as the point of force action. The center of gravity position of the object is the center coordinate position of the circular spot, so as to accurately locate the circular spot, such as Figure 8 As shown, the center coordinates of the precisely positioned light spot are (x c ,y c ), the calculation method is as follows:

[0048]

[0049]

[0050]

[0051] Where: r is the diameter of the circular spot; The coordinates are (x i ,y i ), and W is the sum of the brightness values ​​of the camera pixels in the circular spot.

[0052] Step 3: After determining the center coordinates of each light spot on the display screen and the sum of the brightness values ​​of each camera pixel within the circular light spot, the brightness of each LED pixel on the display screen can be calibrated.

[0053] Example 2

[0054] After the brightness of the display screen is corrected using the method of Example 1, there will be obvious brightness differences at the junction of adjacent areas; therefore, this embodiment uses a regional fusion method to perform uniform transition correction using a weight coefficient at the junction of adjacent areas, so that the human eye cannot see the difference between the two areas. The specific method is as follows:

[0055] Step 1: Divide the display screen into n areas; and the boundaries of adjacent areas overlap, such as Fig. 9 As shown; taking a display screen with an extra-large horizontal size as an example, for an extra-large spliced ​​display screen, the width of the overlapping area can select the width of multiple display modules (the smallest display unit that makes up the display screen), and for a spliced ​​display screen with a slightly larger size, the width of the overlapping area can select the width of 2 display modules; here taking n=5 as an example, the camera is placed at the C position to capture images of each area.

[0056] When shooting, the camera lens can be manually directed to the center point of each area to obtain images of each area. The present invention preferably uses the following method for shooting.

[0057] The camera is placed on the electric control turntable at position C, and its lens optical axis intersects the display screen at point O (i.e., the center point of area III) vertically. According to the vertical distance between the camera lens and the display screen, and the distance between point O and the center points of areas I, II, IV, and V, the angle γ between the line connecting position C and the center points of areas I, II, IV, and V and the normal line of the corresponding area is calculated respectively. 1 , γ 2 , δ 2 , δ 1 .

[0058] Use the camera to take pictures of area III to obtain the image of the area; then control the electric control turntable to rotate γ 1 , γ 1 -γ 2 , γ 2 +δ 2 , δ 1 -δ 2 The camera lens is angled toward the center of areas Ⅰ, Ⅱ, Ⅳ, and Ⅴ to obtain images of each area; when shooting, it is necessary to ensure that all LED pixels in each area are within the camera's field of view.

[0059] Step 2: Use the centroid method to locate each light spot. The specific method is the same as that in Example 1:

[0060] Step 3: For each area, perform brightness correction on the area according to the sum of the center coordinates of each spot and the brightness values ​​of each camera pixel in the circular spot determined in step 2 to obtain the primary brightness correction coefficient of each LED pixel. Since adjacent areas overlap, for LED pixels in non-overlapping areas, their primary brightness correction coefficient is the final correction coefficient; for LED pixels in overlapping areas, there will be a primary correction coefficient corresponding to the correction of the previous area and a primary correction coefficient corresponding to the correction of the next area.

[0061] Step 4: Perform regional fusion to achieve consistent display effects in adjacent areas:

[0062] Calculate the secondary correction coefficient of each overlapping area LED pixel point according to the following method. Take the first overlapping area (i.e. the overlapping area L between area Ⅰ and area Ⅱ) as 1 ) as an example, the overlapping area L 1 The first column of is the first column of area II, and also the mth column of area I. The overlapping area L 1 The last column is the hth column of area II (h is the overlapping area L 1 The total number of LED pixel columns in the area is also the Mth column in area Ⅰ.

[0063] Where Mm=h-1.

[0064] Let the overlapping area L 1 The primary correction coefficient corresponding to area I of the LED pixel point in the i-th column is a (m+i-1) , the first correction coefficient corresponding to area II is b i .

[0065] Then the overlapping area L between area Ⅰ and area Ⅱ is 1 In the equation, the quadratic correction coefficient C of the i-th column of light spots (i=1~h) is L1-i Calculate according to formula (1):

[0066]

[0067] Overlap area L 2 , L 3 , L 4 The calculation method of the secondary correction coefficient and the overlapping area L 1 same.

[0068] Step 5: Overlap Area L 1 , L 2 , L 3 , L 4 The secondary correction coefficient of each LED pixel point is the final correction coefficient, and the final correction coefficient is used to correct each LED pixel point on the display screen.

[0069] With the large-size LED display screen corrected by the present invention, the display effects of adjacent areas are consistent, and any position of the screen has the best viewing effect at the "C position".

[0070] The present invention is not limited to the above embodiment. For an ultra-high LED display screen, it can also be divided into multiple areas in order from top to bottom. For an ultra-high and ultra-wide LED display screen, it can also be divided into multiple square area arrays with overlapping areas, and the above method is used to merge the overlapping areas to correct the brightness consistency of the display screen.

Claims

1. A method for calibrating an LED display screen, characterized in that The method is as follows: The display screen is divided into n independent areas; the camera is set at the C position, and the camera lens is aimed at the center point of each area to obtain the image of each area; the center of gravity method is used to locate the light spot of each area image; the brightness of the LED pixel points in each area is corrected according to the sum of the brightness values ​​of each camera pixel in the light spot, and the brightness correction of the entire display screen is completed; The method of positioning each light spot using the centroid method is as follows: First, mathematical morphology is performed on the images of each region. Then, the threshold of the images after mathematical morphology processing is calculated using the Otsu method. The camera pixel values ​​greater than the threshold are set to 1, and the camera pixel values ​​less than the threshold are set to 0, and the images are converted into binarized images. The light spot outline in the binarized image is obtained, and then the light spot outline is processed into a circular light spot. The center coordinates of the light spot (x c ,y c ): Where: r is the diameter of the circular spot; The coordinates are (x i ,y i ), and W is the sum of the brightness values ​​of the camera pixels in the circular spot.

2. A method for calibrating an LED display screen, characterized in that The method is as follows: The display screen is divided into n areas, and the borders of adjacent areas overlap; the camera is set at the C position, and the camera lens is aimed at the center point of each area to obtain the image of each area; the center of gravity method is used to locate the light spot of each area image; the brightness of the LED pixel points in each area is corrected according to the sum of the brightness values ​​of each camera pixel in each light spot to obtain the final correction coefficient of the LED pixel points in the non-overlapping area and the two primary correction coefficients of the LED pixel points in the overlapping area; For any overlapping area L k For the LED pixel in the ith column or row, let the number of columns or rows in the previous area be p, and the primary correction coefficient be a. p ; In the next area, the number of columns or rows is q, and the primary correction coefficient is b q ; Calculate the secondary correction coefficient of the LED pixel according to the following formula Where h is the total number of columns or rows of LED pixels in the overlapping area; The secondary correction coefficient of each LED pixel in the overlapping area is the final correction coefficient corresponding to each LED pixel; the brightness value of all LED pixels is corrected using the final correction coefficient to complete the brightness correction of the entire display screen; The method of positioning each light spot using the centroid method is as follows: First, mathematical morphology is performed on the images of each region. Then, the threshold of the images after mathematical morphology processing is calculated using the Otsu method. The camera pixel values ​​greater than the threshold are set to 1, and the camera pixel values ​​less than the threshold are set to 0, and the images are converted into binarized images. The light spot outline in the binarized image is obtained, and then the light spot outline is processed into a circular light spot. The center coordinates of the light spot (x c ,y c ): Where: r is the diameter of the circular spot; The coordinates are (x i ,y i ), and W is the sum of the brightness values ​​of the camera pixels in the circular spot.

3. The LED display screen correction method according to claim 1, characterized in that The width of the overlapping area is at least the width of two display modules.

4. The LED display screen correction method according to claim 1 or 2, characterized in that The camera is arranged on an electrically controlled turntable at position C, and the optical axis of the camera lens intersects the display screen at point O vertically; according to the vertical distance between the camera lens and the display screen, and the distance between point O and the center point of each area, the angles between the lines connecting the camera lens and the center point of each area and the normal line of the corresponding area are calculated respectively, and according to the angle calculation results, the electrically controlled turntable is controlled to rotate the corresponding angle so that the camera lens is directed toward the center point of each area to shoot and obtain images of each area.

Images