Parameter calibration methods, devices, electronic equipment, and storage media for projection systems

Abstract

This application discloses a parameter calibration method, apparatus, electronic device, and storage medium for a projection system, relating to the field of projection technology. The method includes: projecting a white field image and a black field image onto a target area using a target projector, and capturing images of the target area using multiple cameras to obtain multiple first images and multiple second images; acquiring multiple brightness distributions of the projected image area in the multiple first images; if the target brightness distribution does not meet preset brightness distribution conditions, iteratively adjusting the display brightness parameters of the target projector and / or the camera parameters until, after adjusting the display brightness parameters and / or camera parameters, the re-acquired target brightness distribution meets the preset brightness distribution conditions, thus obtaining the calibrated display brightness parameters of the target projector and the calibrated camera parameters of the camera. This allows the projected image captured by the camera to automatically adapt to changes in ambient light, maintaining consistent brightness.

Description

Technical Field

[0001] This application relates to the field of projection technology, and in particular to a parameter calibration method, apparatus, electronic device and storage medium for a projection system. Background Technology

[0002] In related technologies, projectors project fringe patterns to assist in functions such as projector focusing, geometric correction, or 3D reconstruction. However, if the brightness of the projected image is inappropriate—for example, too dark and the projected stripes will be unclear, while too bright and the stripes will be overexposed and unresolved—then effectively adapting the projection brightness parameters of the projection system to the environment has become an urgent problem to be solved. Summary of the Invention

[0003] This application proposes a parameter calibration method, apparatus, electronic device, and storage medium for a projection system, so as to adaptively adjust the projection brightness parameters of the projection system.

[0004] In a first aspect, embodiments of this application provide a parameter calibration method for a projection system. The projection system includes multiple projectors and multiple cameras. The method includes: projecting a white field image onto a target area using a target projector and capturing images of the target area using the multiple cameras to obtain multiple first images; and projecting a black field image onto the target area using the target projector and capturing images of the target area using the multiple cameras to obtain multiple second images, wherein each of the multiple second images corresponds one-to-one with the multiple first images, and the target projector is any one of the multiple projectors; acquiring a difference image between each first image and its corresponding second image, and based on the difference image, determining the projected image area formed by the target projector in each first image as the first image. First projection screen area; based on the grayscale value of each pixel in the first projection screen area of ​​each first image, obtain the brightness distribution of each first image, resulting in multiple brightness distributions, each of which corresponds one-to-one with the multiple cameras; if the target brightness distribution does not meet the preset brightness distribution conditions, iteratively adjust the display brightness parameters of the target projector and / or the camera parameters of the target camera until the target brightness distribution, after adjusting the display brightness parameters and / or the camera parameters, meets the preset brightness distribution conditions again, and obtain the adjusted display brightness parameters as the calibration display brightness parameters of the target projector, and obtain the adjusted camera parameters as the calibration camera parameters of the target camera, wherein the target brightness distribution is obtained based on the multiple brightness distributions.

[0005] Secondly, embodiments of this application provide a parameter calibration device for a projection system. The projection system includes multiple projectors and multiple cameras. The device includes: an image acquisition module, a projection area determination module, a brightness distribution acquisition module, and a parameter calibration module. The image acquisition module is used to project a white field image onto a target area using a target projector and capture images of the target area using the multiple cameras to obtain multiple first images; and to project a black field image onto the target area using the target projector and capture images of the target area using the multiple cameras to obtain multiple second images. The multiple second images correspond one-to-one with the multiple first images, and the target projector is any one of the multiple projectors. The projection area determination module is used to acquire a difference image between each first image and its corresponding second image, and based on the difference image, determine the projection area formed by the target projector in each first image as the first projection area of ​​each first image. The brightness distribution acquisition module is used to determine the first projection area of ​​each first image based on the first image. The grayscale value of each pixel in the first projection area of ​​an image is used to obtain the brightness distribution of each first image, resulting in multiple brightness distributions, each corresponding to one of the multiple cameras. A parameter calibration module is used to iteratively adjust the display brightness parameters of the target projector and / or the camera parameters of the target camera if the target brightness distribution does not meet preset brightness distribution conditions, until the adjusted display brightness parameters and / or camera parameters, after which the re-obtained target brightness distribution meets the preset brightness distribution conditions, is used as the calibrated display brightness parameters of the target projector, and the adjusted camera parameters are used as the calibrated camera parameters of the target camera. The target brightness distribution is obtained based on the multiple brightness distributions.

[0006] Thirdly, embodiments of this application provide an electronic device, including: one or more processors; a memory; and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs are configured to perform the methods described above.

[0007] Fourthly, embodiments of this application provide a computer-readable storage medium storing program code that can be invoked by a processor to execute the methods described above.

[0008] In the solution provided in this application, a white field image is projected onto a target area by a target projector, and multiple first images are obtained by capturing images of the target area using multiple cameras. Similarly, a black field image is projected onto the target area by the target projector, and multiple second images are obtained by capturing images of the target area using multiple cameras. Each second image corresponds one-to-one with a first image, and the target projector can be any one of the multiple projectors. A difference image is obtained between each first image and its corresponding second image. Based on the difference image, the projection area formed by the target projector in each first image is determined as the first projection area of ​​each first image. The first projection area of ​​each first image is then determined. The grayscale value of each pixel in the area is used to obtain the brightness distribution of each first image, resulting in multiple brightness distributions, each corresponding to a different camera. If the target brightness distribution does not meet the preset brightness distribution conditions, the display brightness parameters of the target projector and / or the camera parameters of the target camera are iteratively adjusted until the adjusted display brightness parameters and / or camera parameters re-obtain the target brightness distribution that meets the preset brightness distribution conditions. The adjusted display brightness parameters are used as the calibration display brightness parameters of the target projector, and the adjusted camera parameters are used as the calibration camera parameters of the target camera. The target brightness distribution is obtained based on the multiple brightness distributions. In this way, by iteratively adjusting the display brightness parameters of the projector and / or the camera parameters, the multi-camera, multi-projection system can automatically and quickly adjust to reasonable parameters. This ensures that the projected image is within a reasonable brightness range under each projector and camera combination, preventing overexposure or under-exposure. It also ensures that each camera can capture images with brightness distributions that meet the preset brightness distribution conditions, thereby ensuring the normal operation of the projector's focusing, geometric correction, and 3D reconstruction functions. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 A schematic flowchart of a parameter calibration method for a projection system provided in an embodiment of this application is shown.

[0011] Figure 2 A schematic diagram of a projection system provided in an embodiment of this application is shown.

[0012] Figure 3This illustration shows a schematic diagram of a first image provided in an embodiment of this application.

[0013] Figure 4 This illustration shows a schematic diagram of a second image provided in an embodiment of this application.

[0014] Figure 5 It shows Figure 1 A flowchart illustrating a sub-step of step S120 in one embodiment.

[0015] Figure 6 This illustration shows a schematic diagram of a binarized image provided in an embodiment of this application.

[0016] Figure 7 A flowchart illustrating a parameter calibration method for a projection system provided in another embodiment of this application is shown.

[0017] Figure 8 A schematic diagram illustrating the steps of parameter calibration for a projection system provided in an embodiment of this application is shown.

[0018] Figure 9 This is a block diagram of a parameter calibration device for a projection system according to an embodiment of this application.

[0019] Figure 10 This is a block diagram of an electronic device for performing a parameter calibration method for a projection system according to an embodiment of this application.

[0020] Figure 11 This is a storage unit in this application embodiment for storing or carrying program code that implements the parameter calibration method of the projection system according to this application embodiment. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative effort are within the scope of protection of the present application.

[0022] It should be noted that some processes described in the specification, claims, and accompanying drawings of this application include multiple operations that appear in a specific order. These operations may not be performed in the order they appear herein, or they may be performed in parallel. Operation numbers such as S110, S120, etc., are merely used to distinguish different operations and do not represent any execution order. Furthermore, these processes may include more or fewer operations, and these operations may be performed sequentially or in parallel. Also, the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or server that includes a series of steps or sub-modules is not necessarily limited to those steps or sub-modules that are explicitly listed, but may include other steps or sub-modules that are not explicitly listed or that are inherent to such process, method, product, or device.

[0023] In related technologies, projected stripe patterns have multiple applications: projector focusing, geometric correction, 3D reconstruction, and more. However, if the projector brightness is inappropriate—too dim and the projected stripes will be unclear, too bright and the stripes will be overexposed and unresolved—it becomes crucial to calibrate the projector's brightness and adapt it to the environment. Furthermore, for the decoding process of stripe structured light, pixel grayscale values ​​are extremely important, affecting the accuracy and precision of the 3D reconstruction results. To minimize the loss of image acquisition information due to inconsistent camera brightness, adaptive brightness adjustment for different cameras is also necessary.

[0024] Factors such as inconsistent projector brightness, projection distance, projection method, and camera shooting distance can lead to different parameter combinations when different cameras capture images projected from different projectors in order to ensure consistent image brightness. This makes the brightness calibration and adaptive adjustment system of multi-camera, multi-projector systems more complex and requires a feasible solution.

[0025] To address the aforementioned problems, the inventors have proposed a parameter calibration method, apparatus, electronic device, and storage medium for a projection system. The parameter calibration method for the projection system provided in this application will be described in detail below.

[0026] Please refer to Figure 1 , Figure 1 This is a flowchart illustrating a parameter calibration method for a projection system according to an embodiment of this application. The following will be combined with... Figure 1The parameter calibration method for the projection system provided in this application embodiment is described in detail. This parameter calibration method for the projection system may include the following steps:

[0027] Step S110: Project a white field image onto the target area using the target projector, and capture images of the target area using the multiple cameras to obtain multiple first images; project a black field image onto the target area using the target projector, and capture images of the target area using the multiple cameras to obtain multiple second images; the multiple second images correspond one-to-one with the multiple first images; the target projector is any one of the multiple projectors.

[0028] In this embodiment, the projection system includes multiple projectors and multiple cameras, such as... Figure 2 As shown, the projection system 20 may include projectors 211, 212, and 213, cameras 221, 222, 223, and 224. Of course, in practical applications, the number of projectors and cameras included in the projection system may be more or fewer; this embodiment does not limit this. The cameras can be monochrome or color cameras, such as RGB cameras. It should be noted that the shooting range of any one of the multiple cameras can cover the projection range of any one of the multiple projectors.

[0029] Since the projection system contains multiple projectors, the brightness parameters of each projector can be calibrated sequentially, as can the camera parameters of each projector-camera combination. This ensures that in subsequent applications (such as projector focusing, geometric correction, or 3D reconstruction), the stripe pattern projected by each projector remains within a reasonable brightness range, and that the brightness distribution of images captured by each camera is similar, guaranteeing accuracy in subsequent applications. Specifically, a white field image can be projected onto a target area using a target projector (i.e., any one of the multiple projectors), and multiple images can be captured by multiple cameras to obtain multiple first images, each corresponding to one of the multiple cameras; the white field image can be understood as a pure white image. Further, a black field image can be projected onto the target area using the target projector, and multiple images can be captured by multiple cameras to obtain multiple second images, each corresponding to one of the multiple cameras; the black field image can be understood as a pure black image. For example, the target projector projects a white field image onto a target area containing a bear model, and the first images captured by the cameras can be... Figure 3 As shown; and, the target projector projects a black field image onto the target area where the bear model is placed, and the second image captured by the camera can be as follows: Figure 4 As shown.

[0030] by Figure 2 Taking the projection system 20 shown as an example, projector 211 is used as the target projector for brightness parameter calibration. A white field image is projected onto the target area by projector 211, and cameras 221, 222, 223, and 224 each capture images of the target area, resulting in four first images. A black field image is projected onto the target area by projector 211, and cameras 221, 222, 223, and 224 each capture images of the target area, resulting in four second images. Clearly, the four first images and four second images are in one-to-one correspondence; that is, the first image captured by camera 221 corresponds to the second image captured by camera 221. Similarly, if projector 212 or projector 213 is used as the target projector for brightness parameter calibration, the calibration is performed in the same way, and will not be elaborated further here.

[0031] Step S120: Obtain the difference image between each first image and its corresponding second image, and based on the difference image, determine the projection screen area formed by the target projector in each first image as the first projection screen area of ​​each first image.

[0032] Optionally, if the camera is a color camera, a first grayscale image corresponding to each first image is acquired, and a second grayscale image corresponding to each second image corresponding to the first image is acquired, and a difference image between the first grayscale image and the second grayscale image is acquired. The difference image can be used to reflect pixel regions in the first image and its corresponding second image that show significant differences.

[0033] Optionally, if the camera is a monochrome camera, it means that the first image and the second image captured are both grayscale images, so the difference image between each first image and its corresponding second image can be directly obtained.

[0034] It should be noted that the subject of this application is the electronic device with data processing capabilities in the projection system 10 (not included in...). Figure 2 As shown in the figure, the electronic device establishes a wired or wireless communication connection with each camera and each projector, thereby enabling the transmission of data and control signals based on the communication connection.

[0035] In some implementations, please refer to Figure 5 Step S120 may specifically include the contents of steps S121 to S123:

[0036] Step S121: Perform binarization processing on the difference image to obtain the binarized image corresponding to the difference image.

[0037] Binarization can be understood as setting a grayscale threshold, mapping the grayscale values ​​of pixels greater than or equal to the threshold to 255 (i.e., treating these pixels as white), and mapping the grayscale values ​​of pixels less than the threshold to 0 (i.e., treating these pixels as black). In other words, binarization converts the difference image from a grayscale image into a black-and-white image; the resulting binarized image is a grayscale image. This binarized image can also be understood as a mask image that excludes ambient light. Figure 3 For the first image, Figure 4 For the second image, Figure 3 and Figure 4 The difference image is binarized, and the resulting binarized image can be obtained as follows: Figure 6 As shown.

[0038] Step S122: Obtain the location of the white region in the binarized image.

[0039] Step S123: Determine the image region corresponding to the region position of the white area from each of the first images, and use it as the first projection image region of each of the first images.

[0040] In a binary image, the regions mapped as white are the pixel areas where there is a significant difference between the first and second images. Therefore, the location of the white region formed by the white pixels can be obtained based on the pixel positions of all white pixels in the binary image. This white region can be understood as the projected display area formed by multiple first projectors as captured by the camera. Therefore, the image region corresponding to the location of the white region can be determined from the first image as the projected display area formed by multiple first projectors.

[0041] by Figure 2 Taking the projection system 20 shown as an example, projector 211 is used as the target projector for the current brightness parameter calibration; eventually, the projection image area in the first image captured by camera 221, the projection image area in the first image captured by camera 222, the projection image area in the first image captured by camera 223, and the projection image area in the first image captured by camera 224 will be determined.

[0042] Step S130: Based on the grayscale value of each pixel in the first projection area of ​​each first image, obtain the brightness distribution of each first image to obtain multiple brightness distributions, and the multiple brightness distributions correspond one-to-one with the multiple cameras.

[0043] Specifically, based on the grayscale value of each pixel in the first projection area of ​​each first image, a grayscale histogram of each first image is obtained, serving as the brightness distribution of each first image. Further, a target brightness distribution can be determined based on these multiple brightness distributions. Specifically, the average grayscale value of the grayscale values ​​at preset quantiles in the brightness distributions of all first images can be obtained as the target brightness distribution; this target brightness distribution can also be understood as representing the average brightness distribution of images captured by multiple cameras when projecting an image onto a target projector. The grayscale values ​​at preset quantiles can be used to reflect the central trend and dispersion of the grayscale values ​​of each pixel in the first projection area. The preset quantiles are pre-set values, such as 0.90 or 0.95.

[0044] Optionally, if the average gray value is not within the preset gray value range, then the target brightness distribution is determined to not meet the preset brightness distribution conditions; if the average gray value is within the preset gray value range, then the target brightness distribution is determined to meet the preset brightness distribution conditions.

[0045] Step S140: If the target brightness distribution does not meet the preset brightness distribution conditions, the display brightness parameters of the target projector and / or the camera parameters of the camera are iteratively adjusted until the target brightness distribution, after adjusting the display brightness parameters and / or the camera parameters, meets the preset brightness distribution conditions. The adjusted display brightness parameters are used as the calibration display brightness parameters of the target projector, and the adjusted camera parameters are used as the calibration camera parameters of the camera. The target brightness distribution is obtained based on the multiple brightness distribution conditions.

[0046] Among these parameters, brightness is defined as luminous flux; camera parameters include at least one of exposure time, gain, and aperture. The brightness of the projected image is positively correlated with the luminous flux parameter; that is, the higher the luminous flux, the brighter the projected image. Exposure time refers to the time interval from when the camera shutter opens to when it closes, during which an image of an object is captured on film. A longer exposure time allows more light to pass through, resulting in a brighter image. Camera gain primarily refers to adjusting the ISO sensitivity to change the sensor's sensitivity to light, thus affecting image brightness and contrast. Higher ISO results in a brighter image, and vice versa. The camera aperture is a device used to control the amount of light passing through the lens and entering the camera's sensor; it is usually located within the lens. In layman's terms, when a camera lens takes a picture, it's impossible to arbitrarily change the lens diameter. However, the amount of light passing through can be controlled by adding a polygonal or circular variable aperture grating inside the lens. This device is called the aperture. The larger the aperture, the more light enters through the lens, and the brighter the image captured by the camera. Conversely, the smaller the aperture, the lower the brightness. In other words, the brightness of the image captured by the camera is positively correlated with the size of the camera's aperture.

[0047] Optionally, if the target brightness distribution does not meet the preset brightness distribution conditions, and if the grayscale value of a preset quantile in the target brightness distribution is less than the minimum threshold of the preset grayscale value range, then the average brightness of the images captured by multiple cameras is too low. Therefore, the display brightness parameter of the target projector and / or the camera parameter of at least one camera can be iteratively increased until the target brightness distribution, after being increased, meets the preset brightness distribution conditions. The increased display brightness parameter is then used as the calibration display brightness parameter of the target projector, and the increased camera parameter is used as the calibration camera parameter of the at least one camera. The display brightness parameter and camera parameter can be iteratively adjusted based on a preset convergence algorithm, which includes, but is not limited to, commonly used binary search, difference search, or ternary search methods.

[0048] Optionally, if the target brightness distribution does not meet the preset brightness distribution conditions, and the grayscale value of a preset quantile in the target brightness distribution is greater than the maximum threshold of the preset grayscale value range, then the average brightness of the images captured by multiple cameras is too high. Therefore, the display brightness parameters of the target projector and / or the camera parameters of at least one camera can be iteratively reduced until the display brightness parameters and / or the camera parameters are reduced. After this reduction, the target brightness distribution is re-acquired and meets the preset brightness distribution conditions. The reduced display brightness parameters are then used as the calibration display brightness parameters of the target projector, and the reduced camera parameters are used as the calibration camera parameters of the at least one camera.

[0049] In other words, if the grayscale values ​​of the preset quantiles in the re-acquired target brightness distribution are within the preset grayscale value range, then the parameter calibration of the projection system is stopped. The currently adjusted display brightness parameters are used as the calibration display brightness parameters for the target projector, and the adjusted camera parameters are used as the calibration camera parameters for the camera. In this way, after calibrating the brightness parameters for each projector and between each projector and each camera, each projector can project a display image with similar brightness, and each camera can capture an image with suitable and similar brightness, ensuring the normal operation of subsequent applications such as projector focusing, geometric correction, or 3D reconstruction.

[0050] After step S130, if the target brightness distribution meets the preset brightness distribution conditions, then the current display brightness parameter of the target projector and the current camera parameter of each camera are both valid parameters. Thus, the current display brightness parameter of the target projector is determined as the above-mentioned calibration display brightness parameter, and the current camera parameter of each camera is determined as the calibration camera parameter of that camera.

[0051] In this embodiment, by iteratively adjusting the display brightness parameters of the projector and / or the camera parameters, the multi-camera, multi-projector projection system can automatically and quickly adjust to reasonable parameters. This ensures that the image projected by each projector and each camera is within a reasonable brightness range, preventing overexposure or underexposure. It also ensures that each camera can capture images with brightness distribution that conforms to preset brightness distribution conditions, thereby ensuring the normal operation of the projector's focusing, geometric correction, and 3D reconstruction functions.

[0052] Please refer to Figure 7 , Figure 7 This is a flowchart illustrating a parameter calibration method for a projection system according to another embodiment of this application. The following will be combined with... Figure 7The parameter calibration method for the projection system provided in this application embodiment is described in detail. This parameter calibration method for the projection system may include the following steps:

[0053] Step S210: Project a white field image onto the target area using the target projector, and capture images of the target area using the multiple cameras to obtain multiple first images; project a black field image onto the target area using the target projector, and capture images of the target area using the multiple cameras to obtain multiple second images; the multiple second images correspond one-to-one with the multiple first images; the target projector is any one of the multiple projectors.

[0054] Step S220: Obtain the difference image between each first image and its corresponding second image, and based on the difference image, determine the projection screen area formed by the target projector in each first image as the first projection screen area of ​​each first image.

[0055] Step S230: Based on the grayscale value of each pixel in the first projection area of ​​each first image, obtain the brightness distribution of each first image to obtain multiple brightness distributions, and the multiple brightness distributions correspond one-to-one with the multiple cameras.

[0056] Step S240: Obtain the average gray value of the gray values ​​of the preset quantiles in the brightness distribution of all the first images, and use it as the target brightness distribution.

[0057] In this embodiment, the specific implementation of steps S210 to S240 can be found in the content of the foregoing embodiments, and will not be repeated here.

[0058] Step S250: If the average gray value is within the preset gray value range, and it is detected that the gray value of a preset quantile in the brightness distribution of the target image is not within the preset gray value range, then the camera parameters of the target camera used to capture the target image are iteratively adjusted until the gray value of the preset quantile in the obtained specified brightness distribution is within the preset gray value range. The adjusted camera parameters are then used as the calibration camera parameters of the target camera. The target image is any one of the plurality of first images, and the specified brightness distribution is the brightness distribution of the first image recaptured by the target camera after adjusting the camera parameters.

[0059] Understandably, if the average grayscale value is within a preset grayscale value range, it indicates that the projection brightness of the target projector is within a reasonable brightness range. Further, the grayscale values ​​of preset quantiles in the brightness distribution of each first image can be obtained, resulting in multiple grayscale values, each corresponding one-to-one with a first image. Optionally, if it is detected that the grayscale value of a preset quantile in the brightness distribution of a target image is not within the preset grayscale value range, it indicates that the brightness of the image captured by the target camera used to capture that target image is not within a suitable brightness range. Therefore, the camera parameters of the target camera can be iteratively adjusted until, after adjusting the camera parameters, the grayscale values ​​of the preset quantiles in the brightness distribution of the first image recaptured by the target camera are within the preset grayscale value range, and the adjusted camera parameters are used as the calibration camera parameters of the target camera. In this way, the brightness distribution of the images captured by each camera can be made similar.

[0060] Optionally, if the average gray value is within the preset gray value range, and the gray value of the preset quantile in the brightness distribution of the target image is less than the minimum threshold of the preset gray value range, it indicates that the brightness of the image captured by the target camera is low; therefore, the camera parameters of the target camera can be iteratively increased until the brightness distribution of the target camera obtained after increasing the camera parameters meets the preset brightness distribution condition, and the increased camera parameters are used as the calibration camera parameters.

[0061] It should be noted that when iteratively increasing camera parameters, the camera's exposure time is generally adjusted first, for example, by increasing the exposure time. If, after increasing the camera's exposure time, the grayscale value of the preset quantile in the re-acquired specified brightness distribution is still not within the preset grayscale value range, the camera gain can be further increased to avoid introducing excessive noise into the camera's image by directly adjusting the camera gain from the outset. If, after increasing the camera gain, the grayscale value of the preset quantile in the re-acquired specified brightness distribution is still not within the preset grayscale value range, the camera's aperture or gamma can be further increased until the grayscale value of the preset quantile in the re-acquired specified brightness distribution is within the preset grayscale value range. At this point, the adjustment of the camera parameters is stopped, and the increased camera parameters are used as the calibration camera parameters.

[0062] Optionally, if the average gray value is within the preset gray value range, and the gray value of the preset quantile in the brightness distribution of the target image is greater than the maximum threshold of the preset gray value range, it indicates that the brightness of the image captured by the target camera is high; therefore, the camera parameters of the target camera can be iteratively reduced until the gray value of the preset quantile in the obtained specified brightness distribution is within the preset gray value range, and the reduced camera parameters are used as the calibration camera parameters.

[0063] Similarly, when iteratively reducing camera parameters, the camera's exposure time is adjusted first, for example, by reducing the exposure time. If, after reducing the camera's exposure time, the grayscale value of the preset quantile in the re-acquired specified brightness distribution is still not within the preset grayscale value range, the camera gain can be further reduced to avoid introducing excessive noise into the camera's image by directly adjusting the camera gain from the outset. If, after reducing the camera gain, the grayscale value of the preset quantile in the re-acquired specified brightness distribution is still not within the preset grayscale value range, the camera's aperture or gamma can be further reduced until the grayscale value of the preset quantile in the re-acquired specified brightness distribution falls within the preset grayscale value range. At this point, the adjustment of the camera parameters is stopped, and the reduced camera parameters are used as the calibration camera parameters.

[0064] Step S260: If the average grayscale value is not within the preset grayscale value range, the display brightness parameter of the target projector is iteratively adjusted until the average grayscale value obtained after adjusting the display brightness parameter is within the preset grayscale value range. The adjusted display brightness parameter is then used as the calibration display brightness parameter of the target projector. The camera parameters of the target camera are then iteratively adjusted until the grayscale value of the preset quantile in the obtained specified brightness distribution is within the preset grayscale value range. The adjusted camera parameters are then used as the calibration camera parameters.

[0065] Understandably, if the average grayscale value is not within the preset grayscale value range, it indicates that the projection brightness of the target projector is not yet within a reasonable brightness range. Therefore, the display brightness parameters of the target projector can be iteratively adjusted until the average grayscale value, after adjustment, falls within the preset grayscale value range. The adjusted display brightness parameters are then used as the calibrated display brightness parameters of the target projector. In other words, when the average grayscale value is not within the preset grayscale value range, the display brightness parameters of the target projector are calibrated first. Furthermore, after calibrating the display brightness parameters of the target projector, i.e., after ensuring the projection brightness is within a reasonable brightness range, if the aforementioned target camera is detected, the camera parameters of the target camera are iteratively adjusted to achieve calibration. For details on how to iteratively adjust the camera parameters of the target camera, please refer to the aforementioned content, which will not be repeated here.

[0066] Optionally, if the average grayscale value is not within the preset grayscale value range and the average grayscale value is less than the minimum threshold of the preset grayscale value range, it indicates that the projection brightness of the target projector is too low. Therefore, the display brightness parameter of the target projector can be iteratively increased until the average grayscale value obtained after increasing the display brightness parameter is within the preset grayscale value range, and the increased display brightness parameter is used as the calibrated display brightness parameter.

[0067] Optionally, if the average grayscale value is not within the preset grayscale value range and the average grayscale value is greater than the maximum threshold of the preset grayscale value range, it indicates that the projection brightness of the target projector is too high. Therefore, the display brightness parameter of the target projector can be iteratively increased or decreased until the display brightness parameter is decreased and the average grayscale value is re-obtained within the preset grayscale value range. The reduced display brightness parameter is then used as the calibrated display brightness parameter.

[0068] Optionally, if the grayscale value of the preset quantile in the fifth grayscale histogram is not within the preset grayscale value range, the initial brightness parameters of the adjusted target projector and / or the initial camera parameters of the adjusted target camera are iteratively adjusted. If the number of iterations reaches a preset threshold and the preset condition is still not met, a prompt message is output. The prompt message indicates that the parameter calibration of the projection system has failed. The preset threshold is a pre-set value. The prompt message can be output via display, voice, email, or SMS; this embodiment does not limit this method.

[0069] For example, if one projector and N cameras are selected from the aforementioned projection system for brightness parameter calibration, any camera can capture the image projected by any one of the projectors. The selected projector is denoted as the Mth projector. i Projector number (i.e., the target projector mentioned above), where i is an integer. For G ij The overall process for calibrating the brightness parameters can be found in [reference needed]. Figure 8 Therefore, the first step is to initialize and set up the projector Z. i The display brightness factor (i.e., the aforementioned display brightness parameter) and camera parameters of multiple cameras (exposure time, gain, aperture, etc.). Projector M i White and black images are projected sequentially and captured by N cameras. The images are then subtracted and binarized to generate a mask image. The white areas in the mask image represent the projector M. i The projection area of ​​each first image is obtained. Then, the first image captured for the white field image is taken again, and the grayscale histogram of this first image within the white mask area (i.e., the projection area) is calculated. The grayscale value Z at a preset quantile (representing a percentage exceeding, e.g., 0.90, 0.95, set according to scene requirements) in this grayscale histogram is used as the brightness distribution of each first image. The average grayscale value of the preset quantiles in the brightness distribution of all first images is then obtained as the target brightness distribution; subsequently, it is determined whether the average grayscale value is within the preset grayscale value range (Z). min Z max )Inside.

[0070] Optionally, if the average grayscale value is within the preset grayscale value range (Z... min Z maxIf the grayscale value of a target camera (e.g., camera Nj out of N cameras) is detected to be outside the preset grayscale value range in the brightness distribution of the target image, then the camera parameters of the target camera used to capture the target image are iteratively adjusted until the grayscale value of the preset quantile in the acquired specified brightness distribution is within the preset grayscale value range. The adjusted camera parameters are then used as the calibration camera parameters of the target camera. The target image is any one of a plurality of first images, and the specified brightness distribution is the brightness distribution of the first image recaptured by the target camera after adjusting the camera parameters. Specifically, if the average grayscale value is within the preset grayscale value range, and the grayscale value of the preset quantile in the brightness distribution of the target image is less than the minimum threshold of the preset grayscale value range, then the camera parameters of the target camera are iteratively increased until the grayscale value of the preset quantile in the acquired specified brightness distribution is within the preset grayscale value range. The increased camera parameters are then used as the calibration camera parameters. If the average gray value is within the preset gray value range, and the gray value of a preset quantile in the brightness distribution of the target image is greater than the maximum threshold of the preset gray value range, then the camera parameters of the target camera are iteratively reduced until the gray value of the preset quantile in the obtained specified brightness distribution is within the preset gray value range. The reduced camera parameters are then used as the calibrated camera parameters. This yields the effective brightness factor for the aforementioned projector and the reasonable camera parameters for N cameras.

[0071] Optionally, if the average grayscale value is not within the preset grayscale value range (Z), min Z maxWithin a certain range, the display brightness parameters of the target projector are iteratively adjusted until the average grayscale value obtained after adjusting the display brightness parameters is within the preset grayscale value range. The adjusted display brightness parameters are then used as the calibration display brightness parameters of the target projector. The camera parameters of the target camera (e.g., camera Nj out of N cameras) are then iteratively adjusted until the grayscale value of the preset quantile in the obtained specified brightness distribution is within the preset grayscale value range. The adjusted camera parameters are then used as the calibration camera parameters. Specifically, if the average grayscale value is not within the preset grayscale value range, and the average grayscale value is less than the minimum threshold of the preset grayscale value range, then the display brightness parameter of the target projector is iteratively increased until the average grayscale value obtained after increasing the display brightness parameter falls within the preset grayscale value range. The increased display brightness parameter is then used as the calibrated display brightness parameter. If the average grayscale value is not within the preset grayscale value range, and the average grayscale value is greater than the maximum threshold of the preset grayscale value range, then the display brightness parameter of the target projector is iteratively increased or decreased until the display brightness parameter is decreased until the average grayscale value obtained after decreasing falls within the preset grayscale value range. The decreased display brightness parameter is then used as the calibrated display brightness parameter. This yields the effective brightness factor of the aforementioned one projector and the reasonable camera parameters for N cameras.

[0072] It should be noted that this process of continuously adjusting the projector's display brightness parameters and camera parameters is achieved through a preset convergence algorithm, which includes, but is not limited to, binary search, interpolation search, ternary search, etc.

[0073] In this embodiment, by iteratively adjusting the display brightness parameters of the projector and / or the camera parameters, the multi-camera, multi-projection system can automatically and quickly adjust to reasonable parameters. This ensures that the projected image is within a reasonable brightness range for each projector and camera combination, preventing overexposure or underexposure. It also ensures that each camera captures an image with a brightness distribution that conforms to preset brightness distribution conditions, thereby guaranteeing the normal operation of the projector's focusing, geometric correction, and 3D reconstruction functions. In other words, it achieves the goal of automatically adapting the projected image captured by the camera to changes in ambient light, maintaining consistent brightness.

[0074] Please refer to Figure 9The diagram illustrates a structural block diagram of a parameter calibration device 300 for a projection system according to an embodiment of this application. The projection system includes multiple projectors and multiple cameras. The device 300 may include: an image acquisition module 310, a projection area determination module 320, a brightness distribution acquisition module 330, and a parameter calibration module 340.

[0075] The image acquisition module 310 is used to project a white field image onto a target area through a target projector and capture images of the target area through the multiple cameras to obtain multiple first images; and to project a black field image onto the target area through the target projector and capture images of the target area through the multiple cameras to obtain multiple second images. The multiple second images correspond one-to-one with the multiple first images, and the target projector is any one of the multiple projectors.

[0076] The projection area determination module 320 is used to obtain the difference image between each first image and its corresponding second image, and based on the difference image, determine the projection screen area formed by the target projector in each first image as the first projection screen area of ​​each first image.

[0077] The brightness distribution acquisition module 330 is used to acquire the brightness distribution of each first image based on the gray value of each pixel in the first projection area of ​​each first image, and obtain multiple brightness distributions, which correspond one-to-one with the multiple cameras.

[0078] The parameter calibration module 340 is used to iteratively adjust the display brightness parameters of the target projector and / or the camera parameters of the camera if the target brightness distribution does not meet the preset brightness distribution conditions, until the target brightness distribution re-acquired after adjusting the display brightness parameters and / or the camera parameters meets the preset brightness distribution conditions. The adjusted display brightness parameters are used as the calibration display brightness parameters of the target projector, and the adjusted camera parameters are used as the calibration camera parameters of the camera. The target brightness distribution is obtained based on the multiple brightness distribution conditions.

[0079] In some embodiments, the brightness distribution acquisition module 330 may be specifically used to: acquire a grayscale histogram of each first image based on the grayscale value of each pixel in the first projection area of ​​each first image, as the brightness distribution of each first image. The parameter calibration device 300 of the projection system may further include: an average grayscale acquisition module and a brightness distribution judgment module. Specifically, the average grayscale acquisition module may be used to, after acquiring the grayscale histogram of each first image based on the grayscale value of each pixel in the first projection area of ​​each first image, as the brightness distribution of each first image, acquire the average grayscale value of the grayscale values ​​at preset quantiles in the brightness distributions of all first images, as the target brightness distribution. The brightness distribution judgment module may be used to, if the average grayscale value is not within the preset grayscale value range, determine that the target brightness distribution does not meet the preset brightness distribution conditions; if the average grayscale value is within the preset grayscale value range, determine that the target brightness distribution meets the preset brightness distribution conditions.

[0080] In this method, the parameter calibration module 340 can be specifically used to: if the average gray value is within the preset gray value range, and it is detected that the gray value of a preset quantile in the brightness distribution of the target image is not within the preset gray value range, then the camera parameters of the target camera used to capture the target image are iteratively adjusted until the gray value of the preset quantile in the obtained specified brightness distribution is within the preset gray value range, and the adjusted camera parameters are used as the calibration camera parameters of the target camera. The target image is any one of the plurality of first images, and the specified brightness distribution is the result after adjusting the camera parameters. The brightness distribution of the first image recaptured by the target camera; if the average gray value is not within the preset gray value range, the display brightness parameters of the target projector are iteratively adjusted until the average gray value recaptured after adjusting the display brightness parameters is within the preset gray value range, and the adjusted display brightness parameters are used as the calibration display brightness parameters of the target projector. Then, the camera parameters of the target camera are iteratively adjusted until the gray value of the preset quantile in the acquired specified brightness distribution is within the preset gray value range, and the adjusted camera parameters are used as the calibration camera parameters.

[0081] In some embodiments, the parameter calibration module 340 may be specifically used to: if the average gray value is within the preset gray value range, and the gray value of a preset quantile in the brightness distribution of the target image is less than the minimum threshold of the preset gray value range, then the camera parameters of the target camera are iteratively increased until the gray value of the preset quantile in the specified brightness distribution is within the preset gray value range, and the increased camera parameters are used as the calibration camera parameters; if the average gray value is within the preset gray value range, and the gray value of the preset quantile in the brightness distribution of the target image is greater than the maximum threshold of the preset gray value range, then the camera parameters of the target camera are iteratively decreased until the gray value of the preset quantile in the specified brightness distribution is within the preset gray value range, and the decreased camera parameters are used as the calibration camera parameters.

[0082] In some embodiments, the parameter calibration module 340 may also be specifically used for: if the average gray value is not within the preset gray value range and the average gray value is less than the minimum threshold of the preset gray value range, then iteratively increasing the display brightness parameter of the target projector until the average gray value obtained after increasing the display brightness parameter is within the preset gray value range, and obtaining the increased display brightness parameter as the calibrated display brightness parameter; if the average gray value is not within the preset gray value range and the average gray value is greater than the maximum threshold of the preset gray value range, then iteratively increasing or decreasing the display brightness parameter of the target projector until the average gray value obtained after decreasing the display brightness parameter is within the preset gray value range, and obtaining the decreased display brightness parameter as the calibrated display brightness parameter.

[0083] In some embodiments, the projection region determination module 320 may include a difference image acquisition unit and a projection image region determination unit. The difference image acquisition unit may be used to: if the camera is a monochrome camera, acquire a difference image between each first image and its corresponding second image; if the camera is a color camera, acquire a first grayscale image corresponding to each first image, and acquire a second grayscale image corresponding to each second image corresponding to the first image, and acquire a difference image between the first grayscale image and the second grayscale image. The projection image region determination unit may be used to binarize the difference image to obtain a binarized image corresponding to the difference image; acquire the region position of the white area in the binarized image; and determine the image region corresponding to the region position of the white area from each first image as the first projection image region of each first image.

[0084] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the above-described device and module can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0085] In the several embodiments provided in this application, the coupling between modules can be electrical, mechanical, or other forms of coupling.

[0086] Furthermore, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0087] In summary, by iteratively adjusting the projector's display brightness parameters and / or camera parameters, a multi-camera, multi-projector projection system can automatically and quickly adjust to reasonable parameters. This ensures that the projected image is within a reasonable brightness range for each projector and camera combination, preventing overexposure or underexposure. Simultaneously, it ensures that each camera captures an image with a brightness distribution that conforms to preset brightness distribution conditions, thereby guaranteeing the normal operation of the projector's focusing, geometric correction, and 3D reconstruction functions. In other words, it achieves the goal of automatically adapting the projected image captured by the camera to changes in ambient light, maintaining consistent brightness.

[0088] The following will combine Figure 10 This application describes an electronic device.

[0089] Reference Figure 10 , Figure 10 This diagram illustrates a structural block diagram of an electronic device 400 according to an embodiment of this application. The method described above in this embodiment can be executed by this electronic device 400. The electronic device can be an electronic terminal with data processing capabilities, including but not limited to smartphones, tablets, laptops, and desktop computers.

[0090] The electronic device 400 in this application embodiment may include one or more of the following components: processor 401, memory 402, and one or more application programs, wherein the one or more application programs may be stored in memory 402 and configured to be executed by one or more processors 401, and the one or more programs are configured to perform the methods as described in the foregoing method embodiments.

[0091] Processor 401 may include one or more processing cores. Processor 401 connects to various parts within the electronic device 400 using various interfaces and lines, and performs various functions and processes data of the electronic device 400 by running or executing instructions, programs, code sets, or instruction sets stored in memory 402, and by calling data stored in memory 402. Optionally, processor 401 may be implemented using at least one hardware form of Digital Signal Processing (DSP), Field-Programmable Gate Array (FPGA), or Programmable Logic Array (PLA). Processor 401 may integrate one or a combination of several of the following: Central Processing Unit (CPU), Graphics Processing Unit (GPU), and modem. The CPU primarily handles the operating system, user interface, and applications; the GPU is responsible for rendering and drawing the displayed content; and the modem handles wireless communication. It is understood that the aforementioned modem can also be integrated into processor 401 and implemented as a separate communication chip.

[0092] The memory 402 may include random access memory (RAM) or read-only memory (ROM). The memory 402 can be used to store instructions, programs, code, code sets, or instruction sets. The memory 402 may include a program storage area and a data storage area. The program storage area may store instructions for implementing an operating system, instructions for implementing at least one function (such as touch functionality, sound playback functionality, image playback functionality, etc.), and instructions for implementing the various method embodiments described below. The data storage area may also store data created by the electronic device 400 during use (such as the various correspondences described above).

[0093] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the above-described device and module can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0094] In the several embodiments provided in this application, the coupling or direct coupling or communication connection between the modules shown or discussed may be an indirect coupling or communication connection through some interface, device or module, and may be electrical, mechanical or other forms.

[0095] Furthermore, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0096] Please refer to Figure 11 This diagram illustrates a structural block diagram of a computer-readable storage medium provided in an embodiment of this application. The computer-readable medium 500 stores program code that can be called by a processor to execute the methods described in the above method embodiments.

[0097] The computer-readable storage medium 500 may be an electronic memory such as flash memory, EEPROM (Electrically Erasable Programmable Read-Only Memory), EPROM, hard disk, or ROM. Optionally, the computer-readable storage medium 500 includes a non-transitory computer-readable storage medium. The computer-readable storage medium 500 has storage space for program code 510 that performs any of the method steps described above. This program code can be read from or written to one or more computer program products. The program code 510 may be compressed, for example, in a suitable form.

[0098] In some embodiments, a computer program product or computer program is provided, which includes computer instructions stored in a computer-readable storage medium. A processor of an electronic device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the electronic device to perform the steps in the above-described method embodiments.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A parameter calibration method for a projection system, characterized in that, The projection system includes multiple projectors and multiple cameras, and the method includes: A white field image is projected onto a target area by a target projector, and multiple first images are obtained by capturing images of the target area using the multiple cameras. A black field image is projected onto the target area by the target projector, and multiple second images are obtained by capturing images of the target area using the multiple cameras. The multiple second images correspond one-to-one with the multiple first images. The target projector is any one of the multiple projectors. Obtain the difference image between each first image and its corresponding second image, and based on the difference image, determine the projection area formed by the target projector in each first image as the first projection area of ​​each first image; Based on the grayscale value of each pixel in the first projection area of ​​each first image, the brightness distribution of each first image is obtained, resulting in multiple brightness distributions, each of which corresponds to one of the multiple cameras. If the target brightness distribution does not meet the preset brightness distribution conditions, the display brightness parameters of the target projector and / or the camera parameters are iteratively adjusted until the target brightness distribution, after adjusting the display brightness parameters and / or the camera parameters, meets the preset brightness distribution conditions. The adjusted display brightness parameters are then used as the calibration display brightness parameters of the target projector, and the adjusted camera parameters are used as the calibration camera parameters of the camera. The target brightness distribution is obtained based on the multiple brightness distribution conditions.

2. The method according to claim 1, characterized in that, The step of obtaining the brightness distribution of each first image based on the grayscale value of each pixel in the first projection area of ​​each first image includes: Based on the grayscale value of each pixel in the first projection area of ​​each first image, a grayscale histogram of each first image is obtained as the brightness distribution of each first image. After obtaining a grayscale histogram of each first image based on the grayscale value of each pixel in the first projection area of ​​each first image, as the brightness distribution of each first image, the method further includes: The average gray value of the gray values ​​at preset quantiles in the brightness distribution of all the first images is obtained as the target brightness distribution. If the average gray value is not within the preset gray value range, then the target brightness distribution is determined to be inconsistent with the preset brightness distribution conditions. If the average gray value is within the preset gray value range, then the target brightness distribution is determined to meet the preset brightness distribution conditions.

3. The method according to claim 2, characterized in that, If the target brightness distribution does not meet the preset brightness distribution conditions, the display brightness parameters of the target projector and / or the camera parameters of the target camera are iteratively adjusted until the target brightness distribution, after adjusting the display brightness parameters and / or the camera parameters, meets the preset brightness distribution conditions. The adjusted display brightness parameters are then used as the calibration display brightness parameters of the target projector, and the adjusted camera parameters are used as the calibration camera parameters of the target camera. This includes: If the average gray value is within the preset gray value range, and it is detected that the gray value of a preset quantile in the brightness distribution of the target image is not within the preset gray value range, then the camera parameters of the target camera used to capture the target image are iteratively adjusted until the gray value of the preset quantile in the obtained specified brightness distribution is within the preset gray value range. The adjusted camera parameters are then used as the calibration camera parameters of the target camera. The target image is any one of the plurality of first images, and the specified brightness distribution is the brightness distribution of the first image recaptured by the target camera after adjusting the camera parameters. If the average grayscale value is not within the preset grayscale value range, the display brightness parameter of the target projector is iteratively adjusted until the average grayscale value obtained after adjusting the display brightness parameter is within the preset grayscale value range. The adjusted display brightness parameter is then used as the calibration display brightness parameter of the target projector. The camera parameters of the target camera are then iteratively adjusted until the grayscale value of the preset quantile in the obtained specified brightness distribution is within the preset grayscale value range. The adjusted camera parameters are then used as the calibration camera parameters.

4. The method according to claim 3, characterized in that, If the average gray value is within the preset gray value range, and it is detected that the gray value of a preset quantile in the brightness distribution of the target image is not within the preset gray value range, then the camera parameters of the target camera used to capture the target image are iteratively adjusted until the gray value of the preset quantile in the obtained specified brightness distribution is within the preset gray value range. The adjusted camera parameters are then used as the calibration camera parameters of the target camera. The target image is any one of the plurality of first images, and the specified brightness distribution is the brightness distribution of the first image recaptured by the target camera after adjusting the camera parameters, including: If the average gray value is within the preset gray value range, and the gray value of the preset quantile in the brightness distribution of the target image is less than the minimum threshold of the preset gray value range, then the camera parameters of the target camera are iteratively increased until the gray value of the preset quantile in the specified brightness distribution is within the preset gray value range, and the increased camera parameters are used as the calibration camera parameters. If the average gray value is within the preset gray value range, and the gray value of the preset quantile in the brightness distribution of the target image is greater than the maximum threshold of the preset gray value range, then the camera parameters of the target camera are iteratively reduced until the gray value of the preset quantile in the specified brightness distribution is within the preset gray value range, and the reduced camera parameters are used as the calibration camera parameters.

5. The method according to claim 3, characterized in that, If the average grayscale value is not within the preset grayscale value range, the display brightness parameter of the target projector is iteratively adjusted until the average grayscale value obtained after adjusting the display brightness parameter is within the preset grayscale value range. The adjusted display brightness parameter is then used as the calibrated display brightness parameter of the target projector, including: If the average gray value is not within the preset gray value range and the average gray value is less than the minimum threshold of the preset gray value range, then the display brightness parameter of the target projector is iteratively increased until the average gray value is re-obtained within the preset gray value range after the display brightness parameter is increased, and the increased display brightness parameter is used as the calibrated display brightness parameter. If the average grayscale value is not within the preset grayscale value range, and the average grayscale value is greater than the maximum threshold of the preset grayscale value range, then the display brightness parameter of the target projector is iteratively increased or decreased until the display brightness parameter is decreased and the re-acquired average grayscale value is within the preset grayscale value range. The reduced display brightness parameter is then used as the calibrated display brightness parameter.

6. The method according to any one of claims 1-5, characterized in that, The step of obtaining the difference image between each of the first images and its corresponding second image includes: If the camera is a monochrome camera, then the difference image between each first image and its corresponding second image is obtained; If the camera is a color camera, then a first grayscale image corresponding to each first image is obtained, and a second grayscale image corresponding to each second image corresponding to the first image is obtained, and the difference image between the first grayscale image and the second grayscale image is obtained.

7. The method according to any one of claims 1-5, characterized in that, The step of determining, based on the difference image, the projection area formed by the target projector in each first image, as the first projection area of ​​each first image, includes: The difference image is binarized to obtain the corresponding binarized image; Obtain the location of the white region in the binarized image; From each of the first images, an image region corresponding to the location of the white area is determined, which is then used as the first projected image region of each of the first images.

8. A parameter calibration device for a projection system, characterized in that, The projection system includes multiple projectors and multiple cameras, and the device includes: The image acquisition module is used to project a white field image onto a target area through a target projector and capture images of the target area through the multiple cameras to obtain multiple first images; and to project a black field image onto the target area through the target projector and capture images of the target area through the multiple cameras to obtain multiple second images, wherein the multiple second images correspond one-to-one with the multiple first images, and the target projector is any one of the multiple projectors; The projection area determination module is used to acquire the difference image between each first image and its corresponding second image, and based on the difference image, determine the projection screen area formed by the target projector in each first image as the first projection screen area of ​​each first image. The brightness distribution acquisition module is used to acquire the brightness distribution of each first image based on the gray value of each pixel in the first projection area of ​​each first image, thereby obtaining multiple brightness distributions, and the multiple brightness distributions correspond one-to-one with the multiple cameras; The parameter calibration module is used to iteratively adjust the display brightness parameters of the target projector and / or the camera parameters of the camera if the target brightness distribution does not meet the preset brightness distribution conditions, until the target brightness distribution re-acquired after adjusting the display brightness parameters and / or the camera parameters meets the preset brightness distribution conditions. The adjusted display brightness parameters are used as the calibration display brightness parameters of the target projector, and the adjusted camera parameters are used as the calibration camera parameters of the camera. The target brightness distribution is obtained based on the multiple brightness distribution conditions.

9. An electronic device, characterized in that, The electronic device includes: One or more processors; Memory; One or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs being configured to perform the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores program code that can be invoked by a processor to perform the method as described in any one of claims 1 to 7.

Images