Projector backlight adjusting method and device, equipment and medium

Abstract

The invention relates to a projector backlight adjusting method and device, equipment and a medium, and the method comprises the steps: obtaining an original projection picture image projected by a projection lens of a projector photographed by a camera configured on the projector, obtaining each frame of photographed projection picture image in a target coding format, and enabling the projection ratio of the camera to be smaller than the projection ratio of the projection lens; according to the calculation variance of the gray values of the pixels in the same orientation in the multiple frames of shot projection picture images within the preset duration and a preset calibration variance, determining target field information satisfied by the backlight values of the pixels in all orientations in the shot projection picture images from the preset bright and dark field information; determining brightness adjustment information of the original projection picture image according to the target field information; and according to the brightness adjustment information, determining the frequency and the duty ratio of a pulse width modulation signal for backlight adjustment, and according to the frequency and the duty ratio, adjusting the backlight brightness of the original projection picture image corresponding to the projection lens through the backlight driving module.

Description

Technical Field

[0001] The present disclosure relates to the technical field of projectors, and in particular to a method, device, equipment and medium for adjusting backlight of a projector. Background Art

[0002] In the field of projection display technology, if the projector lacks the ability to adaptively adjust ambient light, the display effect of the projected image will vary greatly under different lighting conditions, affecting the user's viewing experience. Traditional bright and dark field detection methods usually rely on simple threshold segmentation or area-based processing, which may lead to poor detection results due to changes in lighting, atmospheric conditions or object occlusion, affecting the display effect of the projected image. Summary of the invention

[0003] The purpose of the present invention is to provide a projector backlight adjustment method, device, equipment and medium, which are intended to intelligently perceive the projection environment light and adaptively adjust the projector backlight, thereby improving the display effect of the projection picture and the user's viewing experience, and for high-lumen projectors, adaptively adjust the projector backlight in a dark field, which can protect eyesight, save energy and reduce heat.

[0004] In order to achieve the above-mentioned purpose, a first aspect of an embodiment of the present disclosure provides a method for adjusting a projector backlight, the method comprising: Acquire the original projection screen image projected by the projection lens of the projector by photographing the original projection screen image through the camera configured on the projector, and obtain the photographed projection screen image of each frame in the target coding format, wherein the projection ratio of the camera is smaller than the projection ratio of the projection lens; According to the calculated variance of the grayscale values ​​of the pixels at the same position in the multiple frames of the captured projection screen image within a preset time length and the preset calibration variance, the target field information satisfied by the backlight values ​​of the pixels at all positions in the captured projection screen image is determined from the preset light and dark field information; Determining brightness adjustment information of the original projection screen image according to the target field information; The frequency and duty cycle of the pulse width modulation signal for backlight adjustment are determined according to the brightness adjustment information, and the backlight brightness of the original projection screen image corresponding to the projection lens is adjusted through the backlight driving module according to the frequency and duty cycle.

[0005] In a possible implementation, the target field information satisfied by the backlight values ​​of the pixels in each direction in the captured projection screen image is determined from preset light and dark field information based on the calculated variance of the grayscale values ​​of the pixels in the same direction in multiple frames of the captured projection screen image within a preset time length and a preset calibration variance, including: Determine the shooting projection intersection points in each direction in each frame of the shooting projection screen image according to the gradient of the grayscale value of each pixel in the multiple frames of the shooting projection screen image within the preset time length, and obtain multiple shooting projection intersection points corresponding to each frame of the shooting projection screen image; Determine, according to a projection ratio difference between a projection ratio of the camera and a projection ratio of the projection lens, a selection range of pixels in the captured projection screen image with each captured projection intersection as a reference point, wherein the selection range is such that the selection range corresponding to any captured projection intersection covers an original projection intersection, wherein the original projection intersection is an intersection of image boundary lines obtained by fitting image boundary points on each edge in each frame of the original projection screen image projected by the projection lens; Select pixels within the selected range from each of the captured projection images within the preset time length, taking each of the captured projection intersections as the reference point, and calculate the calculated variance of the grayscale values ​​of the pixels selected in the same orientation for multiple frames; According to the corresponding calculated variances in various directions and the preset calibration variances, the target field information satisfied by the backlight values ​​of the pixels in various directions in the captured projection screen image is determined from the preset light and dark field information.

[0006] In a possible implementation, determining the target field information satisfied by the backlight values ​​of the pixels in each direction in the captured projection screen image from preset light and dark field information according to the calculated variance corresponding to each direction and the preset calibration variance includes: Calculating the variance difference between the calculated variance corresponding to each of the directions and the preset calibration variance; In the case where the variance difference is less than or equal to the preset difference threshold, if the preset light and dark field information is the light field information, it is determined that the target field information satisfied by the backlight value of the pixel at the position in the captured projection screen image is the light field information; or, if the preset light and dark field information is the dark field information, it is determined that the target field information satisfied by the backlight value of the pixel at the position in the captured projection screen image is the dark field information; In the case where the variance difference is greater than the preset difference threshold, if the preset light and dark field information is bright field information, it is determined that the target field information satisfied by the backlight value of the pixel at that position in the captured projection screen image is dark field information; or, if the preset light and dark field information is dark field information, it is determined that the target field information satisfied by the backlight value of the pixel at that position in the captured projection screen image is bright field information.

[0007] In a possible implementation, the selecting of pixels within the selected range with each of the captured projection intersections as the reference points from each frame of the captured projection screen image within the preset time length, and calculating the calculated variance of the grayscale values ​​of pixels selected from multiple frames at the same orientation include: Selecting pixels within the selected range from each frame of the captured projection screen image within the preset time length, taking each captured projection intersection as the reference point, to obtain a first pixel corresponding to each orientation; Calculating an average value of the grayscale value of the first pixel corresponding to each position of each frame of the captured projection screen image; According to the preset mean value threshold and the mean value corresponding to each orientation, determining whether there is an abnormal pixel with an abnormal gray value in the first pixel corresponding to the orientation; In the case where there are abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to any orientation, the first pixels corresponding to the orientation are screened to remove the abnormal pixels with abnormal grayscale values ​​from the first pixels corresponding to the orientation; When there are no abnormal pixels with abnormal grayscale values ​​corresponding to the first pixels at the same position in each frame of the captured projection screen image within the preset time period, the calculated variance of the grayscale values ​​of the first pixels selected at the same position in multiple frames is calculated.

[0008] In a possible implementation, when there are abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to any orientation, screening the first pixels corresponding to the orientation to remove the abnormal pixels with abnormal grayscale values ​​from the first pixels corresponding to the orientation includes: The following steps are executed in a loop: When there is an abnormal pixel with an abnormal grayscale value in the first pixels corresponding to any orientation, calculate the standard deviation of the grayscale value of the first pixel at the orientation; Taking the average value corresponding to the first pixel corresponding to the orientation as the center and the preset multiple standard deviation as the extension range, determining the target pixel covered by the extension range; Eliminating the target pixel to screen the first pixel corresponding to the orientation to eliminate the abnormal pixel with abnormal gray value from the first pixel corresponding to the orientation; After eliminating the target pixel, the average value of the first pixels that have not been eliminated is calculated, and based on the preset mean threshold and the average value corresponding to the position, it is determined whether there are abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to the position, until there are no abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to the position.

[0009] In a possible implementation, the orientation includes the upper right corner, the lower right corner, the upper left corner and the lower left corner, and when there are no abnormal pixels with abnormal grayscale values ​​for the first pixels corresponding to the same orientation in each frame of the captured projection screen image within the preset time length, calculating the calculated variance of the grayscale values ​​of the first pixels selected at the same orientation in multiple frames includes: In the case that there are no abnormal pixels with abnormal grayscale values ​​for the first pixels corresponding to the same orientation in each frame of the captured projection screen image within the preset time length, the second pixel corresponding to each orientation is obtained according to the first pixels in the selected range, which are selected from each frame of the captured projection screen image within the preset time length, with the captured projection intersection points of the upper right corner, the lower right corner, the upper left corner and the lower left corner as the reference points; According to the grayscale value of the second pixel corresponding to the upper right corner corresponding to each frame of the captured projection screen image within the preset time length, calculating the calculated variance of the grayscale values ​​of the second pixel selected at the upper right corner of multiple frames; According to the gray value of the second pixel corresponding to the lower right corner corresponding to each frame of the captured projection screen image within the preset time length, calculating the calculated variance of the gray values ​​of the second pixel selected at the lower right corner of multiple frames; According to the gray value of the second pixel corresponding to the upper left corner corresponding to each frame of the captured projection screen image within the preset time length, calculating the calculated variance of the gray values ​​of the second pixel selected at the upper left corner of multiple frames; According to the grayscale value of the second pixel corresponding to the lower left corner corresponding to each frame of the captured projection screen image within the preset time length, the calculated variance of the grayscale values ​​of the second pixel selected at the lower left corner of multiple frames is calculated.

[0010] In a possible implementation, determining whether there is an abnormal pixel with an abnormal grayscale value in the first pixel corresponding to each orientation according to a preset mean value threshold and the average value corresponding to each orientation includes: If the mean difference between the mean value corresponding to any of the directions and the preset mean value threshold exceeds a preset value, it is determined that an abnormal pixel with an abnormal grayscale value exists in the first pixel corresponding to the direction; If the mean difference between the average value corresponding to any of the directions and the preset mean threshold value does not exceed the preset value, it is determined that there is no abnormal pixel with abnormal grayscale value in the first pixel corresponding to the direction.

[0011] According to a second aspect of the embodiments of the present disclosure, a projector backlight adjustment device is provided, comprising: An acquisition module is configured to acquire an original projection screen image projected by a projection lens of the projector by photographing the original projection screen image through a camera configured on the projector, and obtain a captured projection screen image of each frame in a target coding format, wherein the projection ratio of the camera is smaller than the projection ratio of the projection lens; The first determination module is configured to determine the target field information satisfied by the backlight values ​​of the pixels at various directions in the captured projection screen image from the preset light and dark field information according to the calculated variance of the grayscale values ​​of the pixels at the same direction in multiple frames of the captured projection screen image within a preset time length and the preset calibration variance; A second determination module is configured to determine the brightness adjustment information of the original projection screen image according to the target field information; The third determination module is configured to determine the frequency and duty cycle of the pulse width modulation signal used for backlight adjustment according to the brightness adjustment information, and adjust the backlight brightness of the original projection screen image corresponding to the projection lens through the backlight driving module according to the frequency and duty cycle.

[0012] According to a third aspect of an embodiment of the present disclosure, a computer-readable storage medium is provided, on which a computer program is stored, and when the program is executed by a processor, the steps of any one of the methods described in the first aspect are implemented.

[0013] According to a fourth aspect of the embodiments of the present disclosure, an electronic device is provided, including: a memory having a computer program stored thereon; A processor is used to execute the computer program in the memory to implement the steps of any one of the methods in the first aspect.

[0014] The present invention provides a projector backlight adjustment method, device, equipment and medium. Compared with the prior art, the present invention has the following beneficial effects: Through the camera configured on the projector, this technology can capture the original picture projected by the projection lens in real time. Since the projection ratio of the camera is smaller than that of the projection lens, the camera can capture wider and finer picture details, and calculate the variance of the pixel grayscale value in the same direction for multiple frames of shooting pictures within a preset time. By comparing with the preset calibration variance, the light and dark change area in the picture can be accurately identified; according to the results of the grayscale analysis, the target field information that the backlight value of the pixels in each direction in the shooting picture image should meet can be determined from the preset light and dark field information. Accurate identification and classification of the picture brightness and darkness are achieved. Based on the target field information, the brightness and darkness adjustment information for the original projection picture image can be formulated. Not only the overall brightness of the picture is considered, but also the balance of local brightness and darkness is taken into account, thereby realizing dynamic adjustment of the picture brightness. According to the brightness and darkness adjustment information, the frequency and duty cycle of the pulse width modulation signal used for backlight adjustment can be determined. Through the backlight driver module, the backlight brightness adjustment instruction is accurately executed, and the backlight brightness of the projection picture is accurately controlled.

[0015] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings: Figure 1 It is a flow chart of a method for adjusting the backlight of a projector according to an embodiment of the specification.

[0017] Figure 2 It is a schematic diagram of the hardware structure of a projector according to an embodiment of the specification.

[0018] Figure 3 It is a block diagram of a projector backlight adjustment device according to an embodiment of the specification.

[0019] Figure 4 It is a block diagram of another projector backlight adjustment device shown in an embodiment of the specification. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of 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.

[0021] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0022] The present invention provides a method for adjusting the backlight of a projector. Figure 1 This is a flow chart of a method for adjusting the backlight of a projector according to an embodiment. The method includes: In step S11, an original projection screen image projected by a projection lens of the projector is obtained by photographing the original projection screen image of the projector through a camera configured on the projector, and a captured projection screen image of each frame in a target coding format is obtained, wherein the projection ratio of the camera is smaller than the projection ratio of the projection lens; Among them, the throw ratio is the ratio between the projection distance and the width of the projected image. It determines the size of the image that can be projected at a specific distance. The projection distance is the shortest distance from the projector lens to the projected image, while the image width refers to the actual width of the projected image. At the same projection distance, the smaller the throw ratio, the wider the projected image.

[0023] The target coding format is a specific format used when image data is stored or transmitted. For example, YUV420P is used as the target coding format. In this way, the image information can be divided into brightness (Y) and chrominance (U, V) for encoding based on the different sensitivities of the visual system to brightness and chrominance. The YUV format allows different sampling and processing of brightness and chrominance, thereby improving coding efficiency and image quality. YUV420P is a planar storage method of the YUV4:2:0 sampling format. In YUV420P, brightness information (Y) and chrominance information (U, V) are stored separately on different planes. Specifically, the Y component (brightness information) is stored independently for each pixel, while the U and V components (chrominance information) share a group for every 4 Y components. This sampling method greatly reduces the storage requirements for chrominance information while maintaining good image quality.

[0024] In the disclosed embodiment, the camera configured on the projector is used to capture the original image projected by the projection lens. Since the projection ratio of the camera is smaller than the projection ratio of the projection lens, this means that the camera can capture a wider image within the same distance, thereby being able to capture background details such as the projection wall in all directions in addition to the original image. The image captured by the camera is then converted into a digital signal and encoded and stored according to the target encoding format.

[0025] For example, suppose the projection ratio of the projector is 1.2, and the projection ratio of the camera is 0.8. When the projector projects a 100-inch screen at a distance of 3 meters, the camera can capture the same or wider screen at a closer distance of 3 meters. In this way, the camera can not only capture the overall projection screen, but also capture more details, such as other background details such as the projection wall in addition to the original screen.

[0026] In step S12, according to the calculated variance of the grayscale values ​​of the pixels at the same orientation in the multiple frames of the captured projection screen image within a preset time length and the preset calibration variance, the target field information satisfied by the backlight values ​​of the pixels at all orientations in the captured projection screen image is determined from the preset light and dark field information; Among them, the gray value is the brightness value of each pixel in the image, usually ranging from 0 (black) to 255 (white). Variance is a statistic used to measure the degree of discreteness of data distribution. For the gray value of pixels in an image, the larger the variance, the greater the difference in the gray value of the pixels, that is, the more uneven the image. The calibration variance is a preset threshold used to determine whether the discrete degree of the gray value of the image meets a certain standard. Bright and dark field information is preset information about the distribution of light and dark in an image, usually including information such as the backlight value corresponding to different brightness areas.

[0027] In the disclosed embodiment, the variance of the grayscale values ​​of pixels at the same position in the projection screen images captured by multiple frames within a preset time length is first calculated. The variance reflects the degree of change in the brightness of the pixels at that position. Then, this variance is compared with the preset calibration variance. If the variance is greater than the calibration variance, it means that the brightness of the pixels at that position varies greatly, which may be caused by uneven backlight or problems with the projection lens.

[0028] Next, according to the preset light and dark field information, the target field information that the backlight value of the pixels in each direction in the captured projection screen image should meet is determined. The target field information is set based on the ideal light and dark distribution, and is used to characterize what brightness level (or darkness level) the pixels in each direction should reach in order to achieve overall brightness uniformity.

[0029] In this way, the uneven light and dark areas in the picture can be accurately identified, and targeted adjustments can be made according to the preset light and dark field information.

[0030] In step S13, according to the target field information, the brightness adjustment information of the original projection screen image is determined; The brightness adjustment information is specific information about how to adjust the brightness of each area of ​​the picture based on the comparison between the target field information and the original projection picture image, which usually includes the brightness increase or decrease of each pixel or pixel area, the brightness adjustment ratio, etc.

[0031] In the disclosed embodiment, the previously determined target field information (i.e., the ideal light and dark distribution) is used for comparison with the original projection screen image. By comparing the brightness value of each pixel or pixel area with the brightness value of the corresponding position in the target field information, the system can calculate the brightness increase or decrease or adjustment ratio of each pixel or area, i.e., the light and dark adjustment information.

[0032] For example, if the brightness value of a certain area in the target field information is 200 (grayscale value), and the brightness value of the corresponding area in the original projection screen image is 150, the system will calculate that the brightness of this area needs to be increased by 50 (grayscale value) and generate corresponding brightness and darkness adjustment information. This information will be used to guide the subsequent backlight adjustment process.

[0033] In step S14, the frequency and duty cycle of the pulse width modulation signal for backlight adjustment are determined according to the brightness adjustment information, and the backlight brightness of the original projection screen image corresponding to the projection lens is adjusted through the backlight driving module according to the frequency and duty cycle.

[0034] Among them, the pulse width modulation (PWM) signal adjusts the average power or brightness of the signal by changing the width (duty cycle) of the pulse. In backlight adjustment, the PWM signal is used to control the brightness of the backlight.

[0035] Frequency is the repetition rate of the PWM signal, that is, the number of times the signal changes from high to low (or from low to high) per second. Duty cycle is the ratio of the duration of the high level (or low level) in the PWM signal to the entire cycle time, which determines the average power or brightness. The backlight driver module is a circuit or component used to receive a PWM signal and adjust the backlight brightness according to the signal.

[0036] In the disclosed embodiment, the frequency and duty cycle of the PWM signal used for backlight adjustment are calculated based on the brightness adjustment information. For example, the brightness adjustment information is converted into parameters of the PWM signal to ensure that the backlight can be adjusted according to the expected brightness.

[0037] For example, if it is determined that the brightness of a certain area needs to be increased, it will generate a PWM signal with a larger duty cycle to drive the backlight. The increase in duty cycle means that the backlight is on for a longer time in each cycle, thereby increasing the average brightness. At the same time, the frequency of the PWM signal is adjusted according to actual needs to ensure the stability and response speed of the backlight adjustment.

[0038] Once the frequency and duty cycle of the PWM signal are determined, these signals are sent to the backlight through the backlight driver module. The backlight driver module receives these signals and adjusts the brightness of the backlight accordingly, thereby achieving precise adjustment of the backlight brightness of the original projected image.

[0039] The above technical solution can capture the original picture projected by the projection lens in real time through the camera configured on the projector. Since the projection ratio of the camera is smaller than the projection ratio of the projection lens, the camera can capture wider and finer picture details, and calculate the variance of the pixel grayscale value in the same direction for multiple frames of shooting pictures within a preset time. By comparing with the preset calibration variance, the light and dark change area in the picture can be accurately identified; according to the result of grayscale analysis, the target field information that the backlight value of the pixels in each direction in the shooting picture image should meet can be determined from the preset light and dark field information. Accurate identification and classification of the picture brightness and darkness are achieved. Based on the target field information, the brightness and darkness adjustment information for the original projection picture image can be formulated. Not only the overall brightness of the picture is considered, but also the balance of local brightness and darkness is taken into account, thereby realizing dynamic adjustment of the picture brightness. According to the brightness and darkness adjustment information, the frequency and duty cycle of the pulse width modulation signal used for backlight adjustment can be determined. Through the backlight driving module, the backlight brightness adjustment instruction is accurately executed, and the backlight brightness of the projection picture is accurately controlled. This improves the user experience. The dynamic adjustment of the backlight brightness can avoid visual discomfort caused by an overly bright or dark screen, making it more comfortable for users to use the device for a long time. The energy-saving effect is significant. By dynamically adjusting the backlight brightness according to the actual ambient light, energy consumption is effectively reduced, especially in dimly lit environments. The backlight brightness will automatically decrease, thereby achieving energy-saving effects. The life of the backlight component is extended: Due to the dynamic adjustment of the backlight brightness, it avoids always running at maximum brightness, and the life of the backlight component is extended, thereby reducing the maintenance cost and replacement frequency of the equipment.

[0040] In a possible implementation, in step S12, the target field information satisfied by the backlight values ​​of the pixels in each direction in the captured projection screen image is determined from the preset light and dark field information according to the calculated variance of the grayscale values ​​of the pixels in the same direction in the multiple frames of the captured projection screen image within a preset time length and the preset calibration variance, including: In step S121, according to the gradient of the grayscale value of each pixel in the multiple frames of the captured projection screen image within the preset time length, the captured projection intersection points in each direction in each frame of the captured projection screen image are determined to obtain multiple captured projection intersection points corresponding to each frame of the captured projection screen image; The grayscale gradient is the rate of change of the grayscale values ​​of adjacent pixels in the image, which is used to detect the edge or change area in the image. The shooting projection intersection is the point formed by the intersection of the projection light and the image plane in the shooting projection screen image, which is usually located at the edge or feature area of ​​the image.

[0041] In the disclosed embodiment, the grayscale value gradient of each pixel in the multiple frames of the projection screen image captured within a preset time length is first calculated. By comparing the grayscale value differences of adjacent pixels, the areas in the image where the grayscale value changes significantly can be identified, and these areas often correspond to the intersections of the projection light and the image plane. For example, in an image containing projected text, the pixel grayscale value gradient at the edge of the text will be larger, so these edge points can be identified as the capture projection intersection. Through this process, the system determines multiple capture projection intersections for each frame of the image.

[0042] In step S122, according to the projection ratio difference between the projection ratio of the camera and the projection ratio of the projection lens, a selection range of pixels in the captured projection screen image is determined with each captured projection intersection as a reference point, wherein the selection range is such that the selection range corresponding to any captured projection intersection covers an original projection intersection, wherein the original projection intersection is an intersection of image boundary lines obtained by fitting image boundary points on each edge in each frame of the original projection screen image projected by the projection lens; The original projection intersection point is the intersection point of the image boundary lines obtained by fitting the image boundary points on each side in the original projection screen image projected by the projection lens.

[0043] In the disclosed embodiment, the pixel selection range with each captured projection intersection as a reference point is determined based on the difference between the projection ratio of the camera and the projection ratio of the projection lens. The purpose of this step is to ensure that the selected pixel range can accurately reflect the information in the original projection image while taking into account the difference in viewing angles between the camera and the projection lens.

[0044] For example, if the camera's throw ratio is smaller than the projection lens' throw ratio, the captured projected image will be smaller than the original projected image, so the system needs to expand the pixel selection range accordingly to ensure that the original projection intersection is covered. Specifically, the system can calculate the relative position of each captured projection intersection and the image boundary, and then adjust the size and shape of the selection range based on the projection ratio difference so that each selection range can cover an original projection intersection. This helps ensure the accuracy and reliability of the backlight value calculation.

[0045] In step S123, pixels within the selected range are selected from each frame of the captured projection image within the preset time length, with each captured projection intersection point as the reference point, and the calculated variance of the grayscale values ​​of pixels selected at the same orientation in multiple frames is calculated; The calculated variance of the grayscale values ​​of pixels selected from multiple frames at the same position is used to measure the discrete degree of the grayscale values ​​of the pixels at the position.

[0046] In the disclosed embodiment, for each frame of the projection screen image captured within a preset time length, each capture projection intersection is used as a reference point to select all pixels within the previously determined pixel range. Then, for each orientation (i.e., the position of each capture projection intersection), the system calculates the variance of the grayscale values ​​of the pixels selected at that orientation in the multiple frames of the image.

[0047] For example, suppose there is a sequence of 10 frames of captured projection images, and 4 captured projection intersections are identified in each frame. For each intersection, a fixed range of pixels around it is selected. Next, the system calculates the variance of the pixel grayscale values ​​selected at the corresponding orientation of each intersection in these 10 frames. This helps to understand the stability or degree of change of the pixel grayscale values ​​at each orientation.

[0048] In step S124, according to the corresponding calculated variances in various directions and the preset calibration variances, the target field information satisfied by the backlight values ​​of the pixels in various directions in the captured projection screen image is determined from the preset bright and dark field information.

[0049] In the disclosed embodiment, the calculated variance of the grayscale values ​​of pixels in each direction is compared with a preset calibration variance, which is preset based on factors such as the actual application scenario, the performance of the projection device, and the image quality requirements.

[0050] The purpose of the comparison is to determine whether the discrete degree of the pixel grayscale value at each direction is within an acceptable range. If the grayscale value variance of a certain direction is much smaller than the calibration variance, it may mean that the pixel brightness at that direction is too stable and lacks the necessary contrast; if the variance is much larger than the calibration variance, it may indicate that the pixel brightness at that direction varies too much, affecting the clarity and readability of the image.

[0051] Based on this comparison result, the information that best matches the target condition is selected from the preset light and dark field information as the target field information that the pixel backlight value at that position should satisfy. For example, if the grayscale value variance at a certain position is moderate and close to the calibration variance, the system may select a target field information with medium brightness; if the variance is large, a target field information with higher contrast and more obvious light and dark contrast may be selected.

[0052] In this way, the backlight value of pixels in all directions in the captured projection screen image can be automatically adjusted to ensure that the entire image can maintain clear visual effects and appropriate contrast under different lighting conditions.

[0053] In a possible implementation, in step S124, determining the target field information satisfied by the backlight values ​​of the pixels in each direction in the captured projection screen image from the preset light and dark field information according to the calculated variance corresponding to each direction and the preset calibration variance, includes: In step S1241, the variance difference between the calculated variance corresponding to each of the directions and the preset calibration variance is calculated; The variance difference is the difference between the calculated variance (ie, the variance of the grayscale values ​​of pixels in each direction obtained in step S123) and the preset calibration variance, and is used to measure the degree of difference between the two.

[0054] In the disclosed embodiment, the grayscale value variance calculated in each direction is compared with the preset calibration variance one by one to calculate the variance difference between them. This difference reflects the degree of deviation between the actual grayscale value fluctuation and the expected fluctuation.

[0055] For example, suppose the calculated grayscale value variance at a certain position is 10, and the preset calibration variance is 8. Then, the variance difference at this position is 10-8 = 2. The system performs this calculation for all positions and obtains a series of variance differences.

[0056] In step S1242, when the variance difference is less than or equal to the preset difference threshold, if the preset bright and dark field information is bright field information, it is determined that the target field information satisfied by the backlight value of the pixel at the position in the captured projection screen image is bright field information; or, if the preset bright and dark field information is dark field information, it is determined that the target field information satisfied by the backlight value of the pixel at the position in the captured projection screen image is dark field information; The preset difference threshold is used to determine whether the variance difference is within an acceptable range, and is set according to the actual application scenario and image quality requirements. Bright field information is the information of the area with higher pixel brightness and more obvious contrast in the image, which is usually used to ensure that important information in the image is clearly visible. Dark field information is the information of the area with lower pixel brightness and weaker contrast in the image, which is often used to highlight specific areas or create a specific atmosphere.

[0057] In the disclosed embodiment, the calculated variance difference is compared with a preset difference threshold. If the variance difference is less than or equal to the preset difference threshold, it means that the gray value fluctuation of the pixel at this position is within an acceptable range and is close to the preset calibration variance.

[0058] Next, the target field information is determined according to the preset light and dark field information. If the preset light and dark field information is the light field information, and the variance difference meets the conditions, then the backlight value of the pixel in this direction should meet the conditions of the light field information, that is, the brightness is high and the contrast is obvious. On the contrary, if the preset light and dark field information is the dark field information, and the variance difference meets the conditions, then the backlight value of the pixel in this direction should meet the conditions of the dark field information, that is, the brightness is low and the contrast is weak.

[0059] For example, assuming that the preset difference threshold is 2, and the variance difference in a certain direction is 1 (less than 2), and the preset bright and dark field information is bright field information, then the backlight value of the pixel in this direction should meet the condition of bright field information, that is, the brightness of the pixel in this direction is increased in subsequent processing to enhance the contrast.

[0060] Through this process, the backlight value of pixels in all directions in the captured projection image can be automatically adjusted according to the fluctuations in the pixel grayscale values ​​in all directions, ensuring that the entire image maintains clear visual effects and appropriate contrast under different lighting conditions.

[0061] In step S1243, when the variance difference is greater than the preset difference threshold, if the preset light and dark field information is bright field information, it is determined that the target field information satisfied by the backlight value of the pixel at that position in the captured projection screen image is dark field information; or, if the preset light and dark field information is dark field information, it is determined that the target field information satisfied by the backlight value of the pixel at that position in the captured projection screen image is bright field information.

[0062] Similarly, if the variance difference is greater than the preset difference threshold, it means that the grayscale value fluctuation of the pixel in a certain direction exceeds the acceptable range and is significantly different from the preset calibration variance. In this case, the target field information is adjusted to adapt to this difference, thereby ensuring the overall quality and visual effect of the image.

[0063] Specifically, if the preset bright and dark field information is bright field information, but the variance difference is greater than the preset difference threshold, it indicates that the grayscale value of the pixel at this position fluctuates too much, which may lead to excessive brightness or contrast. In order to balance this difference, the opposite dark field information is selected as the target field information. This can reduce the brightness of the pixel at this position, reduce the contrast, and make the image smoother and more uniform.

[0064] On the contrary, if the preset bright and dark field information is dark field information, but the variance difference is also greater than the preset difference threshold, this means that the grayscale value fluctuation of the pixel in this direction may also lead to too low brightness or contrast, making the image information difficult to identify. In order to improve this situation, the bright field information is selected as the target field information. Doing so can increase the brightness of the pixels in this direction, enhance the contrast, and make the important information in the image more prominent.

[0065] In a possible implementation, in step S123, selecting pixels within the selected range with each of the captured projection intersections as the reference points from each frame of the captured projection screen image within the preset time length, and calculating the calculated variance of the grayscale values ​​of pixels selected from multiple frames at the same orientation, includes: In step S1231, pixels within the selected range are selected from each frame of the captured projection screen image within the preset time length, with each captured projection intersection point as the reference point, to obtain the first pixel corresponding to each orientation; In the disclosed embodiment, each frame of the projection screen image within a preset time length is first traversed. For each frame of the image, the system uses the known intersection points of the shooting projection (these intersection points are usually obtained through image processing algorithms such as edge detection, feature matching, etc.) as reference points. Then, the system selects a pixel area within a predetermined range with these intersection points as the center. The size of this area is usually determined according to the image resolution, the accuracy of the projection equipment, and the requirements of the actual application scenario. The system extracts all pixels from this area and marks them as the first pixels of the corresponding orientation.

[0066] For example, suppose there is a sequence of 10 frames of projected images, and 4 projected intersections are identified in each frame. For each intersection, a circular area with a radius of 10 pixels and centered at the intersection is set as the selection range. Traverse each frame, and for each intersection, extract all pixels from this circular area and use them as the first pixels of the corresponding position.

[0067] In step S1232, the average grayscale value of the first pixel corresponding to each position of each frame of the captured projection screen image is calculated; In the disclosed embodiment, for each orientation in each frame of image (i.e., the position corresponding to each shooting projection intersection), the average grayscale value of all first pixels in the orientation is calculated. This average value reflects the overall brightness level of the pixels in the orientation. The system performs this calculation for each orientation in each frame of image, thereby obtaining a matrix or array containing the average grayscale values ​​of all orientations.

[0068] Continuing with the above example, assume that the first pixel of all directions has been extracted from each frame of the image. Next, the system will count the grayscale values ​​of these pixels and calculate the average grayscale values ​​of all pixels in each direction. For example, for the direction corresponding to the first intersection, 10 grayscale value averages are obtained in 10 frames of images, which reflect the overall change trend of the pixel brightness in this direction.

[0069] In step S1233, according to the preset mean value threshold and the average value corresponding to each orientation, it is determined whether there is an abnormal pixel with abnormal grayscale value in the first pixel corresponding to the orientation; In the disclosed embodiment, a preset mean value threshold is used to determine whether there are pixels with abnormal grayscale values ​​in each direction. This mean value threshold is usually set based on factors such as the actual application scenario, image quality requirements, and the performance of the projection device. The average grayscale value calculated in each direction is compared with the preset mean value threshold. If the average value of a certain direction exceeds the threshold range (whether it is too high or too low), the system considers that there are pixels with abnormal grayscale values ​​in this direction.

[0070] Continuing with the above example, the average grayscale value of all pixels in each direction is calculated, and a mean threshold range is set (for example, between 50 and 200). Next, the average value of each direction is compared with this threshold range one by one. If the average value of a certain direction is lower than 50 or higher than 200, there are pixels with abnormal grayscale values ​​in this direction. These abnormal pixels may be caused by reasons such as projection equipment failure, light interference, or image processing errors.

[0071] In step S1234, when there are abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to any orientation, the first pixels corresponding to the orientation are screened to remove the abnormal pixels with abnormal grayscale values ​​from the first pixels corresponding to the orientation; In the disclosed embodiment, pixels with abnormal grayscale values ​​may be screened in each direction. If it is determined that there are pixels with abnormal grayscale values ​​(i.e., abnormal pixels) in a certain direction, all first pixels in the direction are further checked. The purpose of this step is to remove those abnormal pixels whose grayscale values ​​obviously deviate from the normal range from the first pixels corresponding to the direction, so as to ensure the accuracy and reliability of subsequent calculations.

[0072] The screening process may involve a variety of methods, such as statistical filtering (such as median filtering, mean filtering, etc.), threshold-based judgment (such as setting a stricter grayscale value range and only retaining pixels within the range) or machine learning-based classification algorithms (such as using a trained model to identify and remove abnormal pixels). The specific method to be used depends on the actual application scenario, image quality requirements, and system processing capacity limitations.

[0073] Suppose that pixels with abnormal grayscale values ​​are found in a certain direction. In order to remove these abnormal pixels, the median filtering method can be used. Specifically, for each first pixel in the direction, select the pixels within a certain range around it (such as a 3x3 or 5x5 neighborhood), and then calculate the median of the grayscale values ​​of these pixels. If the median value is not much different from the grayscale value of the original pixel (for example, the difference is less than a preset threshold), the pixel is retained; otherwise, it is regarded as an abnormal pixel and removed.

[0074] In step S1235, when there are no abnormal pixels with abnormal grayscale values ​​corresponding to the first pixels at the same position in each frame of the captured projection screen image within the preset time length, the calculated variance of the grayscale values ​​of the first pixels selected at the same position in multiple frames is calculated.

[0075] In the disclosed embodiment, the variance of the grayscale values ​​of the first pixels selected at the same orientation in the multi-frame projection screen images is calculated. The premise of this step is that in each frame of the image within the preset time length, there are no abnormal pixels with abnormal grayscale values ​​corresponding to the first pixels at the same orientation. In other words, only when all the first pixels at a certain orientation have passed the screening, the variance of the grayscale value of the orientation is calculated.

[0076] The variance calculation usually involves the following steps: First, for each position, the system summarizes the grayscale values ​​of all the first pixels after filtering; then, the average value (i.e., mean) of these grayscale values ​​is calculated; finally, the square of the difference between each grayscale value and the mean is calculated, and these square values ​​are added and divided by the number of pixels to obtain the variance. The variance reflects the degree of dispersion or fluctuation of the grayscale values ​​of the pixels at that position.

[0077] Assume that pixels without abnormal grayscale values ​​are screened out in each direction. Next, the grayscale value variance of these pixels in each direction can be calculated. Take a certain direction as an example. Assume that there are 100 screened pixels in this direction in 10 frames of images (that is, there are 10 pixels in each frame of image). First, calculate the average grayscale value of these pixels, then calculate the square of the difference between the grayscale value of each pixel and the average value, and add these square values ​​and divide by 100 (that is, the number of pixels) to get the grayscale value variance of this direction.

[0078] In a possible implementation, in step S1234, when there are abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to any orientation, the first pixels corresponding to the orientation are screened to remove the abnormal pixels with abnormal grayscale values ​​from the first pixels corresponding to the orientation, including: The following steps are executed in a loop: In step S21, when there is an abnormal pixel with an abnormal grayscale value in the first pixels corresponding to any orientation, the standard deviation of the grayscale value of the first pixel in the orientation is calculated; In the disclosed embodiment, when an abnormal pixel with an abnormal grayscale value is detected in the first pixel corresponding to any orientation, the standard deviation of the grayscale values ​​of all the first pixels in the orientation is calculated. The standard deviation is an important indicator for measuring the degree of data dispersion, which reflects the degree of deviation of the data point from the average value. Calculating the standard deviation can help the system more accurately identify which pixels' grayscale values ​​deviate from the normal range.

[0079] Assume that there are 10 first pixels in the first frame image at a certain position, and their grayscale values ​​are {50, 52,51, 100, 53, 54, 55, 56, 57, 49}. First, calculate the average value (μ) of these grayscale values, then calculate the square of the difference between each grayscale value and the average value, sum them up and divide them by the number of pixels (N) to get the variance (σ²), and finally take the square root of the variance to get the standard deviation (σ). If the calculated standard deviation is large, it means that the grayscale values ​​of these pixels are highly dispersed, and there may be abnormal pixels.

[0080] In step S22, taking the average value corresponding to the first pixel corresponding to the orientation as the center and the preset multiple standard deviation as the extension range, the target pixel covered by the extension range is determined; In the disclosed embodiment, an interval is determined with the average value of the first pixel corresponding to the orientation as the center and the standard deviation of the preset multiple as the extension range. This interval will cover those pixels that may be abnormal but have not yet been clearly identified, that is, target pixels. The selection of the preset multiple depends on the system's requirements for the sensitivity of abnormal pixels. The larger the multiple, the wider the coverage range, the more abnormal pixels may be included, but it may also include more normal pixels; the smaller the multiple, the narrower the coverage range, and some abnormal pixels may be missed, but the probability of misjudging normal pixels is also reduced.

[0081] Continuing with the above example, assume that the preset multiple is set to 2 and the calculated standard deviation (σ) is 10. Then, the extended range is the mean value (μ) ± 2σ, that is, [μ-20, μ+20]. If the grayscale value of a pixel falls within this range, it is considered to be a target pixel and may need further screening.

[0082] In step S23, the target pixel is removed to screen the first pixels corresponding to the orientation, so as to remove the abnormal pixels with abnormal grayscale values ​​from the first pixels corresponding to the orientation; In the disclosed embodiment, the determined target pixel is eliminated to further screen the first pixel corresponding to the orientation. To remove those pixels that may be abnormal but have not been clearly identified, so as to reduce the error and uncertainty of subsequent calculations. After eliminating the target pixel, the gray value distribution of the remaining pixels is re-evaluated to ensure the accuracy of subsequent analysis.

[0083] In the above example, if there are 10 first pixels, and the grayscale values ​​of 3 pixels fall within the extended range [μ-20, μ+20], then these 3 pixels are considered to be target pixels and are removed. The remaining 7 pixels are considered to be pixels that are more likely to represent the normal grayscale value of the orientation.

[0084] In step S24, after eliminating the target pixel, the average value of the first pixels that have not been eliminated is calculated, and based on the preset mean threshold and the average value corresponding to the position, it is determined whether there are abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to the position, until there are no abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to the position.

[0085] In the disclosed embodiment, the average value of the remaining first pixels after the target pixel is removed is calculated, and based on the preset mean value threshold and the average value corresponding to the position, it is determined again whether there are abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to the position. This step is an iterative process, which aims to gradually approximate the true grayscale value distribution by continuously removing possible abnormal pixels. If after multiple iterations, there are no more abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to the position (that is, the grayscale values ​​of all remaining pixels are within the preset mean value threshold range), the iterative process ends.

[0086] In the above example, if the target pixel is removed and the mean and standard deviation are recalculated, and it is found that the grayscale values ​​of the remaining pixels are within the preset mean threshold range, then there are no abnormal pixels with abnormal grayscale values ​​in the first pixel corresponding to the orientation. If there are still some pixels whose grayscale values ​​exceed the threshold range, the iterative process of steps S21 to S24 is continued until the conditions are met.

[0087] Through this series of steps, pixels with abnormal grayscale values ​​can be more accurately identified and eliminated.

[0088] In a possible implementation, the orientation includes an upper right corner, a lower right corner, an upper left corner, and a lower left corner. In step S1235, when there are no abnormal pixels with abnormal grayscale values ​​for the first pixels corresponding to the same orientation in each frame of the captured projection screen image within the preset time length, calculating the calculated variance of the grayscale values ​​of the first pixels selected at the same orientation in multiple frames includes: In step S31, when there are no abnormal pixels with abnormal grayscale values ​​corresponding to the first pixels in the same orientation in each frame of the captured projection screen image within the preset time length, the second pixel corresponding to each orientation is obtained according to the first pixels in the selected range, which are selected from each frame of the captured projection screen image within the preset time length, with the captured projection intersections of the upper right corner, the lower right corner, the upper left corner and the lower left corner as the reference points; In the disclosed embodiment, first confirm that in each frame of the projection screen image captured within the preset duration, the first pixels corresponding to the same orientation (such as the upper right corner, the lower right corner, the upper left corner and the lower left corner) do not have abnormal pixels with abnormal grayscale values. This ensures the accuracy and reliability of the calculation. Then, according to each frame of the projection screen image captured within the preset duration, the four shooting projection intersection points of the upper right corner, the lower right corner, the upper left corner and the lower left corner are respectively selected as reference points, and a selection range is defined around each reference point. Within this selection range, the system selects the first pixel as the second pixel of the orientation. This process actually extracts and organizes the valid pixels in each orientation in each frame of the image, so as to subsequently calculate the grayscale value variance.

[0089] Assume that the preset duration is 5 seconds, 10 frames are taken per second, and there are 50 frames in total. In each frame, the system uses the upper right corner as the reference point and defines a 5x5 pixel selection range around it. Then, within this range, the system selects the first pixel with a normal grayscale value (i.e., no abnormality) as the second pixel in the upper right corner of the frame. The same process is applied to the lower right corner, upper left corner, and lower left corner. In this way, in each orientation, the system will obtain a set of second pixels in multiple frames.

[0090] In step S32, according to the grayscale value of the second pixel corresponding to the upper right corner corresponding to each frame of the captured projection screen image within the preset time length, the calculated variance of the grayscale values ​​of the second pixel selected at the upper right corner of multiple frames is calculated; In the disclosed embodiment, the variance of the grayscale values ​​of the second pixel selected in the upper right corner of multiple frames is calculated based on the grayscale value of the second pixel in the upper right corner corresponding to each frame of the projection screen image captured within a preset time. This process is actually a calculation application of the statistic of variance. Variance is an important indicator to measure the degree of data dispersion, which reflects the degree of deviation of the data point relative to the average value. In this step, the system first calculates the average value of the grayscale values ​​of all the second pixels in the upper right corner, and then calculates the square of the difference between each grayscale value and the average value, sums these square values ​​and divides them by the number of pixels (i.e., the number of frames) to obtain the variance.

[0091] Continuing with the above example, assume that in 29 frames of image in 1 second, the grayscale value of the second pixel corresponding to each upper right corner has been extracted. These grayscale values ​​may be a sequence, such as {60, 62, 61, 59, ...}. First, calculate the average value of this sequence, then calculate the square of the difference between each grayscale value and the average value, sum these square values ​​and divide them by 29 (i.e. the number of frames) to get the variance of the grayscale value of the second pixel in that direction. This variance value reflects the discreteness or fluctuation of the grayscale value of the second pixel in the upper right corner within the preset duration.

[0092] By calculating the variance, we can understand the discrete degree of the pixel grayscale value in each direction. At the same time, since the variance calculation is based on multiple frames of images, it can also suppress the influence of random noise to a certain extent and improve the accuracy and reliability of the analysis.

[0093] In step S33, according to the grayscale value of the second pixel corresponding to the lower right corner corresponding to each frame of the captured projection screen image within the preset time length, the calculated variance of the grayscale values ​​of the second pixel selected at the lower right corner of multiple frames is calculated; Similarly, the grayscale values ​​of the second pixel corresponding to the lower right corner of these frames are first collected. Then, using these grayscale values, the system calculates the variance of the grayscale values ​​of the second pixel selected at the lower right corner of multiple frames. This variance calculation process is also based on the statistical variance definition, which aims to quantify the degree of dispersion of the grayscale value of the second pixel in the lower right corner relative to its average value.

[0094] Assuming the preset duration of 1 second and the shooting frequency of 29 frames per second as an example again, there are a total of 29 frames. For each frame, a 5x5 pixel area is selected in the lower right corner, and the first pixel with a normal grayscale value is selected as the second pixel of the frame. After all frames are selected, a sequence of 29 grayscale values ​​will be obtained, which correspond to the second pixel in the lower right corner of the 29 frames. Next, the system calculates the average of these grayscale values ​​and calculates the square of the difference between each grayscale value and the average one by one. Finally, these square values ​​are summed and divided by 29 (that is, the number of frames) to obtain the variance of the grayscale value in the lower right corner.

[0095] In step S34, according to the grayscale value of the second pixel corresponding to the upper left corner corresponding to each frame of the captured projection screen image within the preset time length, the calculated variance of the grayscale values ​​of the second pixel selected at the upper left corner of multiple frames is calculated; Similarly, the grayscale values ​​of the second pixel corresponding to the upper left corner of these frames are first collected. Then, using these grayscale values, the system calculates the variance of the grayscale values ​​of the second pixel selected in the upper left corner of multiple frames. This variance calculation process is also based on the statistical variance definition, which aims to quantify the degree of dispersion of the grayscale value of the second pixel in the lower right corner relative to its average value.

[0096] In step S35, according to the grayscale value of the second pixel corresponding to the lower left corner of each frame of the captured projection screen image within the preset time length, the calculated variance of the grayscale values ​​of the second pixel selected at the lower left corner of multiple frames is calculated.

[0097] Similarly, the grayscale values ​​of the second pixel corresponding to the lower left corner of these frames are first collected. Then, using these grayscale values, the system calculates the variance of the grayscale values ​​of the second pixel selected at the lower left corner of multiple frames. This variance calculation process is also based on the statistical variance definition, which aims to quantify the degree of dispersion of the grayscale value of the second pixel in the lower right corner relative to its average value.

[0098] In a possible implementation, in step S1233, determining whether there is an abnormal pixel with an abnormal grayscale value in the first pixel corresponding to the orientation according to the preset mean value threshold and the average value corresponding to each orientation includes: If the mean difference between the average value corresponding to any of the directions and the preset mean value threshold exceeds a preset value, it is determined that an abnormal pixel with an abnormal gray value exists in the first pixel corresponding to the direction; If the mean difference between the average value corresponding to any of the directions and the preset mean threshold value does not exceed the preset value, it is determined that there is no abnormal pixel with abnormal grayscale value in the first pixel corresponding to the direction.

[0099] In the embodiment of the present disclosure, a preset mean value threshold and the average value corresponding to each position are used to determine whether the first pixel at the position has an abnormal pixel with an abnormal grayscale value, which helps to identify and handle potential image quality issues.

[0100] Specifically, the average grayscale value of the first pixel in each orientation (upper right corner, lower right corner, upper left corner, lower left corner) is first calculated. Then, these average values ​​are compared with the preset mean threshold. The preset mean threshold is pre-set according to normal image data and is used to determine whether the grayscale value is within the normal range.

[0101] During the comparison process, the difference between the average value of each position and the preset mean threshold (i.e., mean difference) is calculated. Then, this difference is compared with a preset value (i.e., tolerance or threshold difference). If the mean difference exceeds the preset value, it means that the grayscale value of the position deviates from the normal range, so the system determines that the first pixel of the position has an abnormal pixel with an abnormal grayscale value. On the contrary, if the mean difference does not exceed the preset value, it means that the grayscale value of the position is within the normal range, and it is determined that the first pixel of the position does not have an abnormal pixel with an abnormal grayscale value.

[0102] Assume the following data: preset mean threshold: 128 (assumed to be the median value in the grayscale image); preset value (tolerance): 10 (i.e., the allowable range of fluctuation of the mean value); for a certain orientation (such as the upper right corner), the average grayscale value of the first pixel calculated by the system is 135. Calculate the mean difference: 135 - 128 = 7, compare the mean difference with the preset value: 7<10, because the mean difference is less than the preset value, the system determines that there is no abnormal pixel with abnormal grayscale value in the first pixel in the upper right corner.

[0103] For another orientation (for example, the lower left corner), the system calculates the average grayscale value of the first pixel to be 145. Calculate the mean difference: 145 - 128 = 17, compare the mean difference with the preset value: 17>10, because the mean difference is greater than the preset value, the system determines that the first pixel in the lower left corner has an abnormal grayscale value.

[0104] The above steps can identify the grayscale values ​​in which directions are abnormal, thus providing key information for adjusting projection parameters, marking abnormal areas, etc. This helps to improve the accuracy and efficiency of image processing.

[0105] See also Figure 2 As shown, the projector disclosed in the present invention includes a camera (Camera) 3, a liquid crystal display (Liquid Crystal Display, LCD) 5, a backlight driver module, a system on chip (System on Chip, SoC) 2, a power module (Power) 1, and a projection lens (Lens) 6, wherein the camera 3 is used to take a picture of the current projection image and transmit it to the system on chip (SoC) 2, and the projection ratio of the camera 3 is not less than the projection ratio of the projection lens. The liquid crystal display 5 can be used as a display device to display the image projected by any projection lens; the backlight driving module 4 uses pulse width modulation (PWM) to control the LCD backlight brightness; the system-level chip 2 is used to process the data of the camera 3 into YUV data, obtain a frame of YUV420P data, and take the bytes of size (width * height) as Y data. The image is detected once per second, and the calibration data and algorithm of the automatic trapezoidal algorithm are used to calculate the four corners of the projected image, the range of the four corners of the image and the four corners of the image, and calculate the variance and average difference of the image in these four ranges. According to the variance result, it is judged whether the light and dark information is correct, and then compared with the average difference of the four points during calibration, the current light and dark field is judged, and the backlight is adjusted according to this light and dark value, and the control signal PWM is used to adjust the brightness of the screen. The power module (Power) 1 is used to provide the power required by the entire system. The projection lens (Lens) 6 can project the image of LCD5, project it through the projection lens 6, and form a projection image on the wall or curtain.

[0106] In one implementation, see the code for the relevant calculation process: / / Calculate the average value double getAverage (double *pixels,int n) { double ss = 0.0f,ave = 0.0f; if(pixels != NULL) { for(int i = 0 ; i <n ; i++) { ss += pixels[i]; } } return ss / (double)n; } / / Calculate the variance double getVariance(double *pixels,int n) { double ss = 0.0f,ave = 0.0f; if(pixels != NULL) { ave = getAverage(pixels,n); ss = 0; for(int i = 0 ; i <n ; i++) { ss +="(pixels[i]-ave)*(pixels[i]-ave);"} return n; 计算标准差 double getstvariance(double *pixels,int n) if(pixels !="NULL&&n">0) { return sqrt(getVariance(pixels,n)); } return 0x1fffffff; } / / Calculate the effective average / / Filter out the data with 2 times the variance around the mean, and then calculate the average value double getEffectAverage(double *pixels,int n) { int cnt = 0; double avg1 = 0, avg2 = 0,aag = 0; avg1 = getStVariance(pixels,n); / / Standard deviation avg2 = getAverage(pixels,n); / / average for(int i = 0 ; i <n ; i++) { if(fabs(pixels[i] - avg2)<(avg1*2.0f)) { aag += pixels[i]; cnt++; } } if(cnt>0) { aag / = (double)cnt; } NANOX_MARK("avg1 = %0.2f,avg2 = %0.2f,aag = %0.2f,cnt = %d\n",avg1,avg2,aag,cnt); return 0; } The present disclosure also provides a projector backlight adjustment device. Figure 3 As shown, including: The acquisition module 210 is configured to acquire the original projection screen image projected by the projection lens of the projector by photographing the original projection screen image through the camera configured on the projector, and obtain the captured projection screen image of each frame in the target coding format, wherein the projection ratio of the camera is smaller than the projection ratio of the projection lens; The first determination module 220 is configured to determine the target field information satisfied by the backlight values ​​of the pixels at the same orientation in the captured projection screen image from the preset light and dark field information according to the calculated variance of the grayscale values ​​of the pixels at the same orientation in the multiple frames of the captured projection screen image within a preset time length and the preset calibration variance; The second determination module 230 is configured to determine the brightness adjustment information of the original projection screen image according to the target field information; The third determination module 240 is configured to determine the frequency and duty cycle of the pulse width modulation signal used for backlight adjustment according to the brightness adjustment information, and adjust the backlight brightness of the original projection screen image corresponding to the projection lens through the backlight driving module according to the frequency and duty cycle.

[0107] In a possible implementation, the first determination module 220 is configured to: determine the shooting projection intersection points in each direction in each frame of the shooting projection screen image according to the gradient of the grayscale value of each pixel in the multiple frames of the shooting projection screen image within the preset time length, and obtain multiple shooting projection intersection points corresponding to each frame of the shooting projection screen image; determine the shooting projection intersection point in the shooting projection screen image as a reference point according to the projection ratio difference between the projection ratio of the camera and the projection ratio of the projection lens, and select the pixel selection range in the shooting projection screen image, wherein the selection range makes the selection corresponding to any of the shooting projection intersection points The range covers an original projection intersection point, wherein the original projection intersection point is the intersection point of the image boundary lines obtained by fitting the image boundary points on each side in each frame of the original projection screen image projected by the projection lens; pixels within the selected range are selected from each frame of the captured projection screen image within the preset time length, with each captured projection intersection point as the reference point, and the calculated variance of the grayscale values ​​of pixels selected from multiple frames at the same orientation is calculated; according to the corresponding calculated variances at each orientation and the preset calibration variance, the target field information satisfied by the backlight values ​​of the pixels at each orientation in the captured projection screen image is determined from the preset light and dark field information.

[0108] In one possible implementation, the first determination module 220 is configured to: calculate the variance difference between the calculated variance corresponding to each of the directions and the preset calibration variance; when the variance difference is less than or equal to the preset difference threshold, if the preset light and dark field information is bright field information, determine that the target field information satisfied by the backlight value of the pixel at the direction in the captured projection screen image is bright field information; or, if the preset light and dark field information is dark field information, determine that the target field information satisfied by the backlight value of the pixel at the direction in the captured projection screen image is dark field information; when the variance difference is greater than the preset difference threshold, if the preset light and dark field information is bright field information, determine that the target field information satisfied by the backlight value of the pixel at the direction in the captured projection screen image is dark field information; or, if the preset light and dark field information is dark field information, determine that the target field information satisfied by the backlight value of the pixel at the direction in the captured projection screen image is bright field information.

[0109] In one possible implementation, the first determination module 220 is configured to: select pixels within the selected range with each of the captured projection intersections as the reference points from each frame of the captured projection screen image within the preset time length, and obtain the first pixel corresponding to each of the said directions; calculate the average value of the grayscale values ​​of the first pixels corresponding to each direction of each frame of the captured projection screen image; determine whether there are abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to the direction according to a preset mean threshold and the average value corresponding to each direction; in the case where there are abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to any direction, screen the first pixels corresponding to the direction to eliminate the abnormal pixels with abnormal grayscale values ​​from the first pixels corresponding to the direction; in the case where there are no abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to the same direction in each frame of the captured projection screen image within the preset time length, calculate the calculated variance of the grayscale values ​​of the first pixels selected at the same direction for multiple frames.

[0110] In one possible implementation, the first determination module 220 is configured to: loop the following steps: in the case where there are abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to any orientation, calculate the standard deviation of the grayscale values ​​of the first pixel at the orientation; with the average value corresponding to the first pixel corresponding to the orientation as the center and the preset multiple of the standard deviation as the extension range, determine the target pixels covered by the extension range; eliminate the target pixels to screen the first pixels corresponding to the orientation to eliminate the abnormal pixels with abnormal grayscale values ​​from the first pixels corresponding to the orientation; after eliminating the target pixels, calculate the average value of the first pixels that have not been eliminated, and determine whether there are abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to the orientation based on the preset mean threshold and the average value corresponding to the orientation, until there are no abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to the orientation.

[0111] In a possible implementation, the orientation includes the upper right corner, the lower right corner, the upper left corner and the lower left corner, and the first determination module 220 is configured as follows: when there are no abnormal pixels with abnormal grayscale values ​​corresponding to the first pixels of the same orientation in each frame of the captured projection screen image within the preset time length, the second pixel corresponding to each of the orientations is obtained according to the first pixel within the selected range with the capture projection intersection of the upper right corner, the lower right corner, the upper left corner and the lower left corner as the reference point; the grayscale value of the second pixel corresponding to the upper right corner corresponding to each frame of the captured projection screen image within the preset time length is determined. value, calculate the calculated variance of the grayscale values ​​of the second pixel selected at the upper right corner for multiple frames; calculate the calculated variance of the grayscale values ​​of the second pixel selected at the lower right corner for multiple frames according to the grayscale value of the second pixel corresponding to the lower right corner of each frame of the captured projection screen image within the preset time length; calculate the calculated variance of the grayscale values ​​of the second pixel selected at the upper left corner for multiple frames according to the grayscale value of the second pixel corresponding to the upper left corner of each frame of the captured projection screen image within the preset time length; calculate the calculated variance of the grayscale values ​​of the second pixel selected at the lower left corner for multiple frames according to the grayscale value of the second pixel corresponding to the lower left corner of each frame of the captured projection screen image within the preset time length.

[0112] In one possible implementation, the first determination module 220 is configured as follows: if the mean difference between the average value corresponding to any of the orientations and the preset mean threshold value exceeds a preset value, then it is determined that the first pixel corresponding to the orientation has an abnormal pixel with an abnormal grayscale value; if the mean difference between the average value corresponding to any of the orientations and the preset mean threshold value does not exceed the preset value, then it is determined that the first pixel corresponding to the orientation does not have an abnormal pixel with an abnormal grayscale value.

[0113] The present disclosure also provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps of the method described in any one of the aforementioned embodiments are implemented.

[0114] The present disclosure also provides an electronic device, including: A memory having a computer program stored therein; a processor configured to execute the computer program in the memory to implement the steps of any one of the methods described in the foregoing embodiments.

[0115] Figure 4 The projector backlight adjustment device 100 shown includes: a processor 1001 and a memory 1003. The processor 1001 and the memory 1003 are connected, such as through a bus 1002. Optionally, the projector backlight adjustment device 100 may also include a communication component 1004, which can be used for data interaction between the device 100 and other devices, such as data transmission and / or data reception. It should be noted that in actual scheduling, the communication component 1004 is not limited to one, and the structure of the projector backlight adjustment device 100 does not constitute a limitation on the embodiments of the present application.

[0116] Processor 1001 may be a CPU (Central Processing Unit), a general-purpose processor, a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. It may implement or execute various exemplary logic blocks, modules and circuits described in conjunction with the disclosure of this application. Processor 1001 may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, etc.

[0117] The bus 1002 may include a path to transmit information between the above components. The bus 1002 may be a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus. The bus 1002 may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 4 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0118] The memory 1003 may be a ROM (Read Only Memory) or other types of static storage devices that can store static information and instructions, a RAM (Random Access Memory) or other types of dynamic storage devices that can store information and instructions, or an EEPROM (Electrically Erasable Programmable Read Only Memory), a CD-ROM (Compact Disc Read Only Memory) or other optical disk storage, optical disk storage (including compressed optical disk, laser disk, optical disk, digital versatile disk, Blu-ray disk, etc.), magnetic disk storage medium, other magnetic storage devices, or any other medium that can be used to carry or store program code and can be read by a computer, without limitation herein.

[0119] The memory 1003 is used to store program codes for executing the embodiments of the present disclosure, and the execution is controlled by the processor 1001. The processor 1001 is used to execute the program codes stored in the memory 1003 to implement the steps shown in the embodiment of the projector backlight adjustment method.

[0120] The embodiment of the present disclosure further provides a computer-readable storage medium having program codes stored thereon. When the program codes are executed by a processor, the steps and corresponding contents of the aforementioned projector backlight adjustment method embodiment can be implemented.

[0121] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments; within the technical concept of the present disclosure, various changes, modifications, substitutions and variations may be made to these embodiments, and these changes, modifications, substitutions and variations all fall within the protection scope of the present disclosure.

[0122] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction, and they should also be regarded as the contents disclosed in this disclosure. In order to avoid unnecessary repetition, this disclosure will not further describe various possible combinations. The technical scope of this application is not limited to the contents in the specification, and its technical scope must be determined according to the scope of the claims.< / n>

Claims

1. A method for adjusting the backlight of a projector, characterized in that: The method comprises: Acquire the original projection screen image projected by the projection lens of the projector by photographing the original projection screen image through the camera configured on the projector, and obtain the photographed projection screen image of each frame in the target coding format, wherein the projection ratio of the camera is smaller than the projection ratio of the projection lens; According to the calculated variance of the grayscale values ​​of the pixels at the same position in the multiple frames of the captured projection screen image within a preset time length and the preset calibration variance, the target field information satisfied by the backlight values ​​of the pixels at all positions in the captured projection screen image is determined from the preset light and dark field information; Determining brightness adjustment information of the original projection screen image according to the target field information; The frequency and duty cycle of the pulse width modulation signal for backlight adjustment are determined according to the brightness adjustment information, and the backlight brightness of the original projection screen image corresponding to the projection lens is adjusted through the backlight driving module according to the frequency and duty cycle.

2. The projector backlight adjustment method according to claim 1, characterized in that: The method of determining the target field information satisfied by the backlight values ​​of the pixels at the same orientation in the captured projection screen image from the preset light and dark field information according to the calculated variance of the grayscale values ​​of the pixels at the same orientation in the multiple frames of the captured projection screen image within the preset time length and the preset calibration variance comprises: Determine the shooting projection intersection points in each direction in each frame of the shooting projection screen image according to the gradient of the grayscale value of each pixel in the multiple frames of the shooting projection screen image within the preset time length, and obtain multiple shooting projection intersection points corresponding to each frame of the shooting projection screen image; Determine, according to a projection ratio difference between a projection ratio of the camera and a projection ratio of the projection lens, a selection range of pixels in the captured projection screen image with each captured projection intersection as a reference point, wherein the selection range is such that the selection range corresponding to any captured projection intersection covers an original projection intersection, wherein the original projection intersection is an intersection of image boundary lines obtained by fitting image boundary points on each edge in each frame of the original projection screen image projected by the projection lens; Select pixels within the selected range from each of the captured projection images within the preset time length, taking each of the captured projection intersections as the reference point, and calculate the calculated variance of the grayscale values ​​of the pixels selected in the same orientation for multiple frames; According to the corresponding calculated variances in various directions and the preset calibration variances, the target field information satisfied by the backlight values ​​of the pixels in various directions in the captured projection screen image is determined from the preset light and dark field information.

3. The projector backlight adjustment method according to claim 2, characterized in that: The step of determining target field information satisfied by the backlight values ​​of the pixels in each direction in the captured projection screen image from preset light and dark field information according to the corresponding calculated variances in each direction and the preset calibration variances in each direction includes: Calculating the variance difference between the calculated variance corresponding to each of the directions and the preset calibration variance; In the case where the variance difference is less than or equal to the preset difference threshold, if the preset light and dark field information is the light field information, it is determined that the target field information satisfied by the backlight value of the pixel at the position in the captured projection screen image is the light field information; or, if the preset light and dark field information is the dark field information, it is determined that the target field information satisfied by the backlight value of the pixel at the position in the captured projection screen image is the dark field information; In the case where the variance difference is greater than the preset difference threshold, if the preset light and dark field information is bright field information, it is determined that the target field information satisfied by the backlight value of the pixel at that position in the captured projection screen image is dark field information; or, if the preset light and dark field information is dark field information, it is determined that the target field information satisfied by the backlight value of the pixel at that position in the captured projection screen image is bright field information.

4. The projector backlight adjustment method according to claim 2, characterized in that: The step of selecting pixels within the selected range from each of the captured projection images within the preset time length with each of the captured projection intersections as the reference points, and calculating the calculated variance of the grayscale values ​​of pixels selected from multiple frames at the same orientation includes: Selecting pixels within the selected range from each frame of the captured projection screen image within the preset time length, taking each captured projection intersection as the reference point, to obtain a first pixel corresponding to each orientation; Calculating an average value of the grayscale value of the first pixel corresponding to each position of each frame of the captured projection screen image; According to the preset mean value threshold and the mean value corresponding to each orientation, determining whether there is an abnormal pixel with an abnormal gray value in the first pixel corresponding to the orientation; In the case where there are abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to any orientation, the first pixels corresponding to the orientation are screened to remove the abnormal pixels with abnormal grayscale values ​​from the first pixels corresponding to the orientation; When there are no abnormal pixels with abnormal grayscale values ​​corresponding to the first pixels at the same position in each frame of the captured projection screen image within the preset time period, the calculated variance of the grayscale values ​​of the first pixels selected at the same position in multiple frames is calculated.

5. The projector backlight adjustment method according to claim 4, characterized in that: In the case where the abnormal pixel with abnormal gray value exists in the first pixels corresponding to any orientation, the first pixels corresponding to the orientation are screened to remove the abnormal pixel with abnormal gray value from the first pixels corresponding to the orientation, including: The following steps are executed in a loop: When there is an abnormal pixel with an abnormal grayscale value in the first pixels corresponding to any orientation, calculate the standard deviation of the grayscale value of the first pixel at the orientation; Taking the average value corresponding to the first pixel corresponding to the orientation as the center and the preset multiple standard deviation as the extension range, determining the target pixel covered by the extension range; Eliminating the target pixel to screen the first pixel corresponding to the orientation to eliminate the abnormal pixel with abnormal gray value from the first pixel corresponding to the orientation; After eliminating the target pixel, the average value of the first pixels that have not been eliminated is calculated, and based on the preset mean threshold and the average value corresponding to the position, it is determined whether there are abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to the position, until there are no abnormal pixels with abnormal grayscale values ​​in the first pixels corresponding to the position.

6. The projector backlight adjustment method according to claim 4, characterized in that: The orientation includes the upper right corner, the lower right corner, the upper left corner and the lower left corner. When there are no abnormal pixels with abnormal grayscale values ​​corresponding to the first pixels of the same orientation in each frame of the captured projection screen image within the preset time length, the calculated variance of the grayscale values ​​of the first pixels selected at the same orientation in multiple frames is calculated, including: In the case that there are no abnormal pixels with abnormal grayscale values ​​for the first pixels corresponding to the same orientation in each frame of the captured projection screen image within the preset time length, the second pixel corresponding to each orientation is obtained according to the first pixels in the selected range, which are selected from each frame of the captured projection screen image within the preset time length, with the captured projection intersection points of the upper right corner, the lower right corner, the upper left corner and the lower left corner as the reference points; According to the grayscale value of the second pixel corresponding to the upper right corner corresponding to each frame of the captured projection screen image within the preset time length, calculating the calculated variance of the grayscale values ​​of the second pixel selected at the upper right corner of multiple frames; According to the gray value of the second pixel corresponding to the lower right corner corresponding to each frame of the captured projection screen image within the preset time length, calculating the calculated variance of the gray values ​​of the second pixel selected at the lower right corner of multiple frames; According to the gray value of the second pixel corresponding to the upper left corner corresponding to each frame of the captured projection screen image within the preset time length, calculating the calculated variance of the gray values ​​of the second pixel selected at the upper left corner of multiple frames; According to the grayscale value of the second pixel corresponding to the lower left corner corresponding to each frame of the captured projection screen image within the preset time length, the calculated variance of the grayscale values ​​of the second pixel selected at the lower left corner of multiple frames is calculated.

7. The projector backlight adjustment method according to claim 4, characterized in that: The step of determining whether there is an abnormal pixel with an abnormal grayscale value in the first pixel corresponding to the orientation according to the preset mean value threshold and the average value corresponding to each orientation includes: If the mean difference between the mean value corresponding to any of the directions and the preset mean value threshold exceeds a preset value, it is determined that an abnormal pixel with an abnormal grayscale value exists in the first pixel corresponding to the direction; If the mean difference between the average value corresponding to any of the directions and the preset mean threshold value does not exceed the preset value, it is determined that there is no abnormal pixel with abnormal grayscale value in the first pixel corresponding to the direction.

8. A projector backlight adjustment device, characterized in that: include: An acquisition module is configured to acquire an original projection screen image projected by a projection lens of the projector by photographing the original projection screen image through a camera configured on the projector, and obtain a captured projection screen image of each frame in a target coding format, wherein the projection ratio of the camera is smaller than the projection ratio of the projection lens; The first determination module is configured to determine the target field information satisfied by the backlight values ​​of the pixels at various directions in the captured projection screen image from the preset light and dark field information according to the calculated variance of the grayscale values ​​of the pixels at the same direction in multiple frames of the captured projection screen image within a preset time length and the preset calibration variance; A second determination module is configured to determine the brightness adjustment information of the original projection screen image according to the target field information; The third determination module is configured to determine the frequency and duty cycle of the pulse width modulation signal used for backlight adjustment according to the brightness adjustment information, and adjust the backlight brightness of the original projection screen image corresponding to the projection lens through the backlight driving module according to the frequency and duty cycle.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method described in any one of claims 1 to 7 are implemented.

10. An electronic device, characterized in that: include: a memory having a computer program stored thereon; A processor, configured to execute the computer program in the memory to implement the steps of the method according to any one of claims 1 to 7.

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