A method, system, device and medium for improving pixel accuracy

Abstract

The present invention relates to a method, system, device and medium for improving pixel accuracy, the method comprising: selecting an image to be projected; calibrating points on the image; projecting the image onto a screen and photographing the projected image; defining an area including a certain number of pixels with the calibrated point as the center in the photographed image; and obtaining the sub-pixel coordinates of the calibrated point according to the characteristics of each pixel in the area. The method is simple and fast to draw calibration points; the designed calibration points can greatly improve the accuracy of the sub-pixel coordinates represented; and the proposed sub-pixel coordinate calculation method is fast and robust.

Description

Technical Field

[0001] The present invention belongs to the field of virtual vision, and in particular relates to a method, system, device and medium for improving pixel accuracy. Background Art

[0002] In the flight simulator visual system, when performing operations such as stitching correction, a common method is to use a camera to collect the calibration points projected by the projector for correction. In the recognition of calibration points, color recognition, grayscale threshold and other methods are usually used to identify the calibration point pixel parts that stand out compared to the background in the camera-taken picture. The higher the accuracy of calibration point recognition, the better the effect of program correction. However, since the image is composed of pixels and the coordinates of the pixels are integers, the traditional representation method cannot provide high-precision coordinate representation, and the minimum accuracy is only at the 0.5 pixel level.

[0003] In the prior art, the interpolation method is used to calculate the sub-pixel value by weighted averaging the grayscale or color between adjacent pixels, or to determine the sub-pixel coordinates by detecting the sub-pixel change of the pixel edge. By analyzing the change of pixel grayscale or color, the edge position of the sub-pixel level can be identified, thereby realizing the representation of sub-pixel coordinates; or the image can be converted from the spatial domain to the frequency domain by Fourier transform, and the sub-pixel coordinates can be determined by analyzing the sub-pixel information in the image spectrum; or the four integer coordinates around the point to be represented are used, and the average of the coordinates of these four points is the precise sub-pixel coordinates of the point to be represented. However, these technologies have the following disadvantages: due to the limitations of the camera's own resolution and shooting environment, the color or grayscale of the calibration point projected by the projector cannot be accurately identified, resulting in low robustness of the system; the use of auxiliary information such as QR codes to identify the sub-pixel change of the pixel edge has low recognition efficiency, complex algorithms, and cannot adapt well to non-planar imaging and other situations; the Fourier frequency domain analysis method has a complex algorithm; the method of using multiple points to represent a sub-pixel cannot meet the recognition requirements of multiple sub-pixel coordinates in parallel. Therefore, a method is needed to represent sub-pixel coordinates on a pixel-level image to meet the accuracy requirements of the correction algorithm. Summary of the invention

[0004] In order to overcome the problems existing in the prior art, the present invention provides a pixel accuracy improvement method, system, device and medium, which are used to overcome the current defects.

[0005] A method for improving pixel accuracy, the method comprising the steps of:

[0006] S1. Select the image to be projected;

[0007] S2. The coordinates of a point in the image to be projected are (X, Y), and the abscissa X and the ordinate Y are both the sum of the integer part and the decimal part; the abscissa is X=Xi’ +X d , the vertical coordinate is Y=Y i’ +Y d , where X i’ is the integer part of X, X d is the decimal part of X, Y i’ is the integer part of Y, Y d is the fractional part of Y, i' and d are positive integers, the fractional part X d and Y d Divide into multiple intervals, in each interval there is a calibrated point corresponding to the point, the coordinates of the calibrated point are calculated according to X d and Y d Calculated according to the corresponding relationship in each interval;

[0008] S3. Projecting the image onto a screen and photographing the projected image;

[0009] S4. In the captured image, a region including a certain number of pixels is defined with the calibrated point as the center;

[0010] S5. According to the characteristics of each pixel in the area, the sub-pixel coordinates of the calibrated point are obtained as follows: , where M and N are the number of pixel rows and columns in the area, respectively. is the coordinate of a pixel in the i-th row and j-th column of the region, It is the grayscale value of the pixel in the i-th row and j-th column of the area, where i is [0, M-1] and j is [0, N-1].

[0011] According to the above aspects and any possible implementation, an implementation is further provided, wherein the intervals are five, namely .

[0012] According to the above aspects and any possible implementation, an implementation is further provided, wherein the maximum difference between the calibrated coordinates of the point and the actual coordinates is less than 0.18.

[0013] The present invention also provides a pixel accuracy improvement system, wherein the system implements the method described above and comprises the following modules:

[0014] A selection module, used for selecting an image to be projected;

[0015] A calibration module, used for calibrating points on the image;

[0016] A projection module, used for projecting the image onto a screen and photographing the projected image;

[0017] A partitioning module is used to define an area including a certain number of pixels with the calibrated point as the center in the captured image;

[0018] The obtaining module is used to obtain the sub-pixel coordinates of the calibrated point according to the characteristics of each pixel in the area.

[0019] The present invention further provides an electronic device, comprising:

[0020] A memory storing executable instructions;

[0021] A processor is used to execute the executable instructions in the memory to implement the method.

[0022] The present invention also provides a computer storage medium, on which a computer program is stored, and the computer program is executed by a processor to implement the method described.

[0023] Beneficial effects of the present invention

[0024] The pixel accuracy improvement method of the present invention comprises the following steps: selecting an image to be projected; calibrating points on the image; projecting the image onto a screen and photographing the projected image; defining an area including a certain number of pixels with the calibrated point as the center in the photographed image; and obtaining the sub-pixel coordinates of the calibrated point according to the characteristics of each pixel in the area. The method is simple and quick to draw the calibration points; the designed calibration points can greatly improve the accuracy of the sub-pixel coordinates represented; and the proposed sub-pixel coordinate calculation method is fast and robust. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram for calibrating points of an image to be projected;

[0026] Figure 2 A schematic diagram of demarcating areas for captured images. DETAILED DESCRIPTION

[0027] In order to better understand the technical solution of the present invention, the content of the present invention includes but is not limited to the specific implementation methods described below, and similar technologies and methods should be considered to be within the scope of protection of the present invention. In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

[0028] It should be clear that the embodiments described in the present invention are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The present invention provides a method for improving pixel accuracy, the method comprising the steps of:

[0030] S1. Select the image to be projected;

[0031] S2. Calibrate the points on the image;

[0032] S3. Projecting the image onto a screen and photographing the projected image;

[0033] S4. In the captured image, a region including a certain number of pixels is defined with the calibrated point as the center;

[0034] S5. According to the characteristics of each pixel in the area, the sub-pixel coordinates of the calibrated point are obtained. The point calibrated in S2 is represented by coordinates (X, Y), where the horizontal coordinate X and the vertical coordinate Y are the sum of the integer part and the decimal part respectively; the horizontal coordinate X=X i’ +X d , the vertical coordinate is Y=Y i’ +Y d , where X i’ is the integer part of X, X d is the decimal part of X, Y i’ is the integer part of Y, Y d is the decimal part of Y, i' and d are positive integers; the decimal part is divided into several decimal intervals, and the present invention preferably adopts five decimal intervals, which are respectively This division makes the position of the calibrated point in the captured image more accurate, so that the calculation accuracy of the subsequent sub-pixel coordinates is relatively high and accurate; in the picture obtained by shooting the projected image, the characteristics of each pixel in the selected area of ​​the calibration point include the coordinates and grayscale values ​​of each pixel in the defined area; the maximum difference between the coordinates of the calibrated point and the actual coordinates is less than 0.18.

[0035] The present invention takes into account the situation that the lens is out of focus during the two links of projecting the image by the projector and shooting by the camera, and the pixels in a small range will become blurred, which is equivalent to a smoothing filter. Based on this projection situation, the present invention represents different sub-pixel coordinates in different intervals with different point forms. This special point is projected onto the screen and photographed by the camera. In the picture taken by the camera, the sub-pixel coordinates of the point can be calculated by processing simple grayscale.

[0036] Specifically, the specific process of the present invention is as follows:

[0037] 1. Calibration point design

[0038] Let the coordinates of a point in the image to be projected be (X, Y), X=X i’ +Xd , Y=Y i’ +Y d , where X i’ is the integer part of X, X d is the fractional part of X, where Y i’ is the integer part of Y, Y d is the fractional part of Y, i' and d are positive integers. d and Y d Divided into intervals Five parts (including Indicates that the left interval is included. Indicates that the right interval is not included). The calibration point diagram corresponding to each interval is as follows Figure 1 The gray dots represent the integer part of the coordinates in the image to be projected (X i’ , Y i’ ) is located.

[0039] Table 1 below shows the X d , Y d The coordinates of the calibration points calculated according to the corresponding relationship in each interval. Because the weight of each pixel in the original image is fixed, black is 0 and white is 255. It can be seen that the maximum difference between the calculated coordinates and the actual coordinates of this set of calibration points is 0.18 pixels, that is, the accuracy of the coordinates represented by the calibration point is 0.18 pixels.

[0040] Table 1: Each image is sorted by X d , Y d The coordinates of the corresponding calibration points

[0041]

[0042] 2. Sub-pixel coordinate calculation

[0043] This method proposes a grayscale-based weighted average coordinate calculation method. Figure 2 For example, after the image to be projected is projected on the screen, a camera is used to capture the image on the screen to obtain a captured image. In the captured image, find the pixel represented by the point calibrated in step 1. Define an area with a length and width of M and N pixels with the pixel represented by this calibration point as the center. , that is, the area The number of pixels in is indivual. is The coordinates of a pixel in the i-th row and j-th column of the region, It should The grayscale value of the pixel in the i-th row and j-th column of the region, i is [0, M-1], j is [0, N-1], for example, the coordinates of the pixel in the 0th row and 0th column are is (0, 0), and the grayscale value of the pixel is obtained by the camera; for example, the coordinates of the pixel in the M-1th row and the N-1th column are (M-1, N-1), and the grayscale value of the pixel is obtained by the camera.

[0044] The sub-pixel coordinates of the calibration points in this area are calculated as:

[0045] .

[0046] As an embodiment disclosed in the present invention, the present invention further discloses a pixel accuracy improvement system, wherein the system implements the method described, and comprises the following modules:

[0047] A selection module, used for selecting an image to be projected;

[0048] A calibration module, used for calibrating points on the image;

[0049] A projection module, used for projecting the image onto a screen and photographing the projected image;

[0050] A partitioning module is used to define an area including a certain number of pixels with the calibrated point as the center in the captured image;

[0051] The obtaining module is used to obtain the sub-pixel coordinates of the calibrated point according to the characteristics of each pixel in the area.

[0052] As an embodiment disclosed in the present invention, the present invention further discloses an electronic device, the electronic device comprising:

[0053] A memory storing executable instructions;

[0054] A processor is used to execute the executable instructions in the memory to implement the method described in the present invention.

[0055] As an embodiment disclosed in the present invention, the present invention further discloses a computer storage medium, on which a computer program is stored, and the computer program is executed by a processor to implement the method described in the present invention.

[0056] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0057] The above description shows and describes several preferred embodiments of the present invention, but as mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not depart from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A method for improving pixel accuracy, characterized in that: The method comprises the steps of: S1. Select the image to be projected; S2. The coordinates of a point in the image to be projected are (X, Y), and the abscissa X and the ordinate Y are both the sum of the integer part and the decimal part; the abscissa is X=X i’ +X d , the vertical coordinate is Y=Y i’ +Y d , where X i’ is the integer part of X, X d is the decimal part of X, Y i’ is the integer part of Y, Y d is the fractional part of Y, i' and d are positive integers, the fractional part X d and Y d Divide into multiple intervals, in each interval there is a calibrated point corresponding to the point, the coordinates of the calibrated point are calculated according to X d and Y d Calculated according to the corresponding relationship in each interval; S3. Projecting the image onto a screen and photographing the projected image; S4. In the captured image, a region including a certain number of pixels is defined with the calibrated point as the center; S5. According to the characteristics of each pixel in the area, the sub-pixel coordinates of the calibrated point are obtained as follows: , where M and N are the number of pixel rows and columns in the area, respectively. is the coordinate of a pixel in the i-th row and j-th column of the region, It is the grayscale value of the pixel in the i-th row and j-th column of the area, where i is [0, M-1] and j is [0, N-1].

2. The pixel accuracy improvement method according to claim 1, characterized in that: There are five intervals, namely .

3. The pixel accuracy improvement method according to claim 1, characterized in that: The maximum difference between the calibrated coordinates of the point and the actual coordinates is less than 0.

18.

4. A pixel accuracy improvement system, characterized in that: The system implements the method described in any one of claims 1 to 3, and includes the following modules: A selection module, used for selecting an image to be projected; A calibration module, used for calibrating points on the image; A projection module, used for projecting the image onto a screen and photographing the projected image; A partitioning module is used to define an area including a certain number of pixels with the calibrated point as the center in the captured image; The obtaining module is used to obtain the sub-pixel coordinates of the calibrated point according to the characteristics of each pixel in the area.

5. An electronic device, characterized in that: The electronic device comprises: A memory storing executable instructions; A processor, wherein the processor runs the executable instructions in the memory to implement the method according to any one of claims 1 to 3.

6. A computer storage medium, characterized in that: The medium stores a computer program, and the computer program is executed by a processor to implement the method according to any one of claims 1 to 3.

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