Display screen correction method based on human eye resolution

Abstract

The invention belongs to the technical field of LED display optical acquisition correction, and provides a display screen correction method based on human eye resolution in order to solve the problem that the calculation amount of point-by-point correction of a display screen is huge and unnecessary in an existing method. According to a relational expression between the pixel pitch P and a limit distance L between the human eyes and the display screen and capable of distinguishing two adjacent pixel points and a fixed watching distance S, a limit distance D capable of being distinguished by the human eyes on the display screen is deduced, collection and correction are carried out according to small areas divided into D * D, and a correction coefficient of each area is calculated; multiplying the weight of the lamp points in the area by the correction coefficient of the area to obtain the correction coefficient of each lamp point; the watching effect of the human eyes is guaranteed, meanwhile, the collection efficiency is improved, and unnecessary waste of computing resources is reduced.

Description

Technical Field

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

[0002] Due to the discreteness of LED light emission and performance attenuation, different LED light emitting dies with the same specifications will emit different brightness or chromaticity under the same voltage and current, which will lead to uneven brightness and chromaticity of LED display. In order to improve the display uniformity of LED display and enhance the viewing comfort of users, LED display correction technology has emerged.

[0003] Visual acuity is the ability of the human eye to distinguish the fine structure of an object, also known as the resolution of the human eye. It is defined as the reciprocal of the angle of view between two points that the human eye can distinguish. It is also called visual acuity in clinical practice. The minimum angle of view that the human eye can distinguish is generally around 1' for normal eyes, and can reach 0.5' in the best case.

[0004] Current display screen calibration technology usually calculates the calibration coefficient for each light point separately. However, the resolution of the human eye is limited. When viewing at a fixed distance, the minimum distance that the human eye can distinguish is greater than the pixel pitch of the display screen. In other words, the human eye can no longer distinguish a single light point. Therefore, calibrating each display pixel is undoubtedly a waste of resources and has low calibration efficiency. Summary of the invention

[0005] In order to solve the problem that the existing method of point-by-point correction of the display screen is computationally huge and unnecessary, the present invention comprehensively considers the pixel spacing and viewing distance according to the resolution of the human eye, and proposes a display screen correction method based on the resolution of the human eye.

[0006] like Figure 1 As shown, the display screen correction method based on human eye resolution includes the following steps: The relationship between the pixel pitch P and the limit distance L between the human eye and the display screen that can distinguish two adjacent pixel points is as follows:

[0007] (P / 2) / L=tan(U0 / 2),①

[0008] Among them, U0 represents the angle threshold when the human eye can distinguish two adjacent pixels, P represents the pixel pitch, and L represents the maximum distance from the human eye to the display screen that can distinguish two adjacent pixels, thereby defining the fixed viewing distance as S, S ≥ L;

[0009] like Figure 2 As shown, tan(U0 / 2)=(D / 2) / S,②

[0010] Among them, U0 represents the angle threshold when the human eye can distinguish two adjacent pixels, S represents the fixed viewing distance, and D represents the limit distance that the human eye can distinguish on the display screen. After D is derived, the display screen is divided into multiple small areas with a length and width of D;

[0011] The data is collected and corrected according to the divided areas, and the correction coefficient of each area is calculated. The correction coefficient of each light point in the area is multiplied by the weight of the light point in this area to obtain the correction coefficient of each light point; the correction coefficient of the obtained light point is input into the control system to complete the correction of the LED display.

[0012] Technical effects:

[0013] If a display screen has m×n light points, the previous correction method needs to collect data from each light point to calculate the correction coefficient. The present invention introduces the human eye resolution to perform regional calculations. It only needs to determine a fixed viewing distance S, divide the display screen into multiple small areas with a length and width of D according to the inferred D, collect data from the small areas, and then calculate the correction coefficient by allocating weights. This not only ensures the viewing effect of the human eye, but also improves the collection efficiency and reduces unnecessary waste of computing resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the relationship between the pixel pitch P and the maximum distance L between the human eye and the display screen that can distinguish two adjacent pixels.

[0015] Figure 2 Schematic diagram of the relationship between the maximum distance D that the human eye can distinguish on the display screen and the fixed viewing distance S.

[0016] Figure 3 Schematic diagram of calculating the lamp point correction coefficient in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] In the application of LED display screens, the determination of fixed viewing distance is closely related to the resolution of human eyes. Figure 1 As shown, the pixel pitch P and the limit distance L between the human eye and the display screen that can distinguish two adjacent pixels are mutually constrained, and the relationship between the two is expressed by the following formula:

[0018] (P / 2) / L=tan(U0 / 2),①

[0019] Among them, U0 represents the angle threshold when the human eye can distinguish adjacent pixels. This angle is usually described by the minimum resolution angle, and the minimum resolution angle for the standard human eye is 1'. Therefore, if the pixel pitch P of the LED display is given, the above formula can be used to calculate the limit distance at which the human eye can clearly distinguish pixels.

[0020] When the fixed viewing distance is defined as S, in order to ensure a good display effect, the fixed viewing distance S in actual application should be greater than or equal to L, such as Figure 2 As shown:

[0021] tan(U0 / 2)=(D / 2) / S,②

[0022] Among them, U0 represents the angle threshold when the human eye can distinguish two adjacent pixels, S represents the fixed viewing distance, and D represents the maximum distance that the human eye can distinguish on the display screen, that is, the human eye will not be able to distinguish two objects (light points) below this distance. After D is derived, the display screen is divided into multiple D×D small areas.

[0023] The acquisition and correction are performed according to the divided areas, and the correction coefficient of each area is calculated as follows: the physical size of the display screen is defined as H in height and W in width, with m×n light points, all the light points of the display screen are lit, and a camera is placed at a distance S from the center of the display screen to acquire a picture of the display screen, and the center position of the light spot of each light point in the picture is determined; according to the calculated D, the display screen is divided into X×Y small areas with a length and width of D, X=H / D, Y=W / D, and the grayscale integral value in each small area is set to L ij , then the correction coefficient a for each small area ij for:

[0024]

[0025] The weight of each small area is determined according to the center position of the light spot of each light point in the camera imaging. The product of the weight in the small area and the correction coefficient of the area is used as the final correction coefficient of each light point:

[0026] C mn =a ij ×w1+a ij+1 ×w2+a i+1j ×w3+a i+1j+1 ×w4,

[0027] Among them, w represents the weight, w1+w2+w3+w4=1, C mn Load it into the control system to complete the calibration of the LED display.

[0028] Example:

[0029] Ideally, when the viewing angle is small enough, that is, the radian is close to 0, the tangent value can be approximately equal to the radian itself, that is, tan(U0 / 2)≈U0 / 2, ③

[0030] Substituting formula ③ into formula ②, we get: D = U0 × S;

[0031] Similarly, from formula ①, we can get: P = U0 × L; ⑤

[0032] In summary, since S≥L, D≥P, that is, the human eye can no longer distinguish a single light point, so correcting each display pixel is undoubtedly a waste of resources, resulting in extremely low correction efficiency.

[0033] First, according to formula ⑤, the maximum distance L that the human eye can distinguish between two adjacent pixels on the display screen is calculated based on the pixel pitch P, L = P / U0,

[0034] According to the actual situation, the user can specify a fixed viewing distance S, or directly set S≥L;

[0035] According to formula ④, the limit distance D that the human eye can distinguish on the display screen is deduced, D = U0 × S,

[0036] like Figure 3 As shown, after the calculation of the present invention, D is obtained, and the display screen is divided into 4 small areas of D×D, with a total of 9 lamp points. The first row and the first column are lamp point 1, and all lamp point 1 is in area 1. The correction coefficient of area 1 is a1, so the correction coefficient of the lamp point is a1×1; the first row and the second column are lamp point 2, the pixel ratio in area 1 is 4 / 13, and the pixel ratio in area 2 is 9 / 13. The correction coefficients of area 1 and area 2 are a1 and a2 respectively, so the correction coefficient of the lamp point is a1× 4 / 13+a2×9 / 13; the second row and second column is lamp 5, its proportion in area 1 is 1 / 13, its proportion in area 2 is 3 / 13, its proportion in area 3 is 3 / 13, and its proportion in area 4 is 6 / 13. The correction coefficients of areas 1, 2, 3, and 4 are a1, a2, a3, and a4 respectively. Then the correction coefficient of this lamp point is a1×1 / 13+a2×3 / 13+a3×3 / 13+a4×6 / 13; and so on. The correction coefficient of each lamp point can be calculated.

[0037] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

Claims

1. A display screen calibration method based on human eye resolution, characterized in that: The method comprises the following steps: The relationship between the pixel pitch P and the limit distance L between the human eye and the display screen that can distinguish two adjacent pixels is as follows: (P / 2) / L=tan(U0 / 2), Among them, U0 represents the angle threshold when the human eye can distinguish two adjacent pixels, P represents the pixel pitch, and L represents the maximum distance from the human eye to the display screen that can distinguish two adjacent pixels, thereby defining the fixed viewing distance as S, S ≥ L; tan(U0 / 2)=(D / 2) / S, Among them, U0 represents the angle threshold when the human eye can distinguish two adjacent pixels, S represents the fixed viewing distance, and D represents the limit distance that the human eye can distinguish on the display screen. After D is derived, the display screen is divided into multiple small areas with a length and width of D; The data is collected and corrected according to the divided areas, and the correction coefficient of each area is calculated. The correction coefficient of each light point in the area is multiplied by the weight of the light point in this area to obtain the correction coefficient of each light point; the correction coefficient of the obtained light point is input into the control system to complete the correction of the LED display.

2. The display screen correction method based on human eye resolution according to claim 1, characterized in that: The correction coefficient of each area is calculated as follows: the physical size of the display screen is defined as H in height and W in width, with m×n light points. All the light points of the display screen are lit, and a camera is placed at a distance S from the center of the display screen to capture a picture of the display screen. The center position of the light spot of each light point in the picture is determined; according to the calculated D, the display screen is divided into X×Y small areas with a length and width of D, X=H / D, Y=W / D, and the grayscale integral value in each small area is set to L ij , then the correction coefficient a for each small area ij for:

3. The display screen correction method based on human eye resolution according to claim 2, characterized in that: The weight of each small area is determined according to the center position of the light spot of each light point in the camera imaging. The product of the weight in the small area and the correction coefficient of the area is used as the final correction coefficient of each light point: G mn =a ij ×w1+a ij+1 ×w2+a i+1j ×w3+a i+1j+1 ×w4, Among them, w represents the weight, w1+w2+w3+w4=1, C mn Load it into the control system to complete the calibration of the LED display.

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