Projection picture correction method, and projection device

Abstract

The present application relates to a projection picture correction method, and a projection device. The method comprises: acquiring a captured image captured when a projection device projects a preset image, wherein the preset image comprises a positioning mark and a correction mark, the positioning mark is used for positioning the preset image, and the correction mark is used for performing precision correction; and determining an image correction parameter on the basis of the positioning mark and the correction mark, and correcting a projection picture on the basis of the image correction parameter. By means of the present application, accurate coordinates of a projector screen in a projection device coordinate system required for projection picture correction can be determined on the basis of a captured image, such that the difficulty in projection picture correction can be reduced, and the efficiency and accuracy of projection picture correction can also be improved.

Description

Projection image calibration methods and projection equipment

[0001] This application claims priority to Chinese Patent Application No. 202410932408.6, filed on July 11, 2024, entitled “Projection Image Correction Method and Projection Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of projection technology, specifically to a projection image correction method and projection device. Background Technology

[0003] In the field of projection technology, achieving accurate image calibration for projection devices without built-in cameras has become a technical challenge. These devices cannot directly use a camera to capture the projected image for calibration, therefore traditional image comparison-based calibration methods are not applicable in this scenario. Summary of the Invention

[0004] This application discloses a projection screen calibration method and projection device, which can determine the accurate coordinates of the projection screen in the projection device coordinate system based on only one captured image, thereby reducing the difficulty of projection screen calibration and improving the efficiency and accuracy of projection screen calibration.

[0005] In a first aspect, this application relates to a projection screen correction method, comprising: acquiring a captured image, wherein the captured image is captured when a projection device projects a preset image, and the preset image covers the projection screen area; wherein the preset image includes a positioning mark and a correction mark; the positioning mark is used to position the preset image, and the correction mark is used to perform accuracy correction; determining image correction parameters based on the positioning mark and the correction mark, and correcting the projection screen based on the image correction parameters.

[0006] Optionally, the positioning marker is located in the central area of ​​a preset image, and the positioning marker includes one or more marker graphics.

[0007] Optionally, the correction mark is located in the boundary area of ​​the preset image, and the correction mark is set around the positioning mark; the correction mark includes one or more mark graphics.

[0008] Optionally, before the above-mentioned "determine image correction parameters" step, the first vertex coordinates of the vertex of the preset image in the coordinate system of the captured image are determined, and the corresponding area of ​​the preset image in the captured image is determined based on the first vertex coordinates; the projection screen area is determined within the area corresponding to the preset image in the captured image, and the second vertex coordinates of the vertex of the projection screen area in the coordinate system corresponding to the captured image are determined.

[0009] Optionally, the above-described steps for determining image correction parameters include: determining a plurality of nearest neighbor markers of the vertices of the projection screen area from the correction markers; selecting a preset number of nearest neighbor markers with the largest enclosing area from the plurality of nearest neighbor markers, and using the selected preset number of nearest neighbor markers as a plurality of first markers; and determining image correction parameters based on the plurality of first markers.

[0010] Optionally, the above step of determining the image correction parameters based on multiple first marks includes: determining a precision correction coefficient based on the coordinates of the multiple first marks in the coordinate system corresponding to the captured image and the coordinates of the second vertex; wherein the second vertex coordinates represent the coordinates of the vertex of the projection screen area in the coordinate system corresponding to the captured image; and determining the image correction parameters based on the precision correction coefficient and the coordinates of the multiple first marks in the coordinate system of the display chip of the projection device.

[0011] Optionally, the vertices of the projection screen area include the upper left vertex, upper right vertex, lower left vertex, and lower right vertex of the projection screen area.

[0012] Optionally, the above-mentioned step of correcting the projected image according to the image correction parameters includes: controlling the projection device to determine the vertex coordinates of the image to be projected according to the image correction parameters, so that the projected image corresponding to the image to be projected is aligned with the projection screen area.

[0013] Optionally, the projection image correction method further includes: determining multiple boundary points of the projection screen area, and determining the image correction parameters corresponding to each of the multiple boundary points according to the correction marks; and performing distortion correction on the projected image after the projection image correction is performed according to the image correction parameters corresponding to each boundary point.

[0014] In a second aspect, this disclosure also provides a projection device, including: one or more processors; a memory; and one or more application programs, wherein the one or more application programs are stored in the memory and configured to be executed by the processor to implement the projection image correction method of the first aspect described above.

[0015] Thirdly, this disclosure also provides a computer-readable storage medium having a computer program stored thereon, the computer program being loaded by a processor to perform a projection image correction method.

[0016] This application relates to a projection screen calibration method, a projection device, and a storage medium. The method involves constructing a specific projection scene and capturing an image of that scene in a single photograph. Based on the vertices of the projection screen in the captured image and specific markers in the projected image, image calibration parameters are determined for calibrating the projection screen. This allows for rapid and accurate calibration of the projection screen. Specifically, when constructing the projection scene, a pre-constructed image with specific markers can be projected onto the projection screen using the projection device, ensuring the projected image covers the entire screen area. This allows the accurate coordinates of the projection screen in the projection device's coordinate system to be determined from just one captured image, based on the vertices of the projection screen and nearby markers in the captured image. This reduces the difficulty of projection screen calibration and improves its efficiency and accuracy. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this disclosure, 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 disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 is an application scenario diagram of the projection image correction method provided in the embodiments of this application.

[0019] Figure 2 is a flowchart of the projection image correction method provided in the embodiment of this application.

[0020] Figure 3 is an example of a preset image provided in an embodiment of this application.

[0021] Figure 4 is an example of a preset image provided in an embodiment of this application.

[0022] Figure 5 is an example of a captured image provided in an embodiment of this application.

[0023] Figure 6 is a flowchart illustrating the determination of the position of the vertex of the projection screen area in the captured image, provided in an embodiment of this application.

[0024] Figure 7 is a flowchart of determining image correction parameters provided in an embodiment of this application.

[0025] Figure 8 is a schematic diagram of the projection device provided in an embodiment of this application. Detailed Implementation

[0026] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0027] It should be understood that the various steps described in the method embodiments of this disclosure may be performed in different orders and / or in parallel. Furthermore, method embodiments may include additional steps and / or omit the steps shown. The scope of this disclosure is not limited in this respect.

[0028] The term "comprising" and its variations as used herein are open-ended inclusions, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Definitions of other terms will be given in the description below.

[0029] It should be noted that the concepts of "first" and "second" mentioned in this disclosure are used only to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0030] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0031] The names of messages or information exchanged between multiple devices in the embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of such messages or information.

[0032] For example, Figure 1 shows an application scenario of the projection screen correction method provided in this application embodiment. A projection device (e.g., projection device 101 in Figure 1) projects an image onto a projection screen (e.g., projection screen 102 in Figure 1). In order to provide users with a better visual experience, it is usually necessary to correct the projection screen of the projection device (e.g., projection screen 103 in Figure 1) so that the projection screen projected by the projection device is aligned with the projection screen.

[0033] In related technologies, methods for correcting projection screens based on images captured by terminal devices (such as mobile phones) typically require the terminal device to take at least multiple shots. By comparing the images obtained from multiple shots, the position of the projected image in the captured images is determined, thereby adjusting the projected image.

[0034] For example, in related technologies, a mobile phone takes two images: the first image is the background before the projector projects an image, and the second image is the image after the projector projects an image. By comparing these two images, the position of the projected image on the mobile phone camera's coordinate system is determined, thus achieving screen alignment.

[0035] However, the above methods are relatively cumbersome to operate and have high requirements for the shooting environment. For example, if the shooting environment has complex lighting or the shooting device has camera distortion, it may affect the accuracy of the projected image correction. In addition, if the projection screen is uneven, the above methods cannot achieve accurate correction of the projected image.

[0036] To address the aforementioned issues, this application provides a projection screen correction method. By constructing a specific projection scene, a single image can be captured of the scene. Based on the vertices of the projection screen in the captured image and specific markers in the projection screen, image correction parameters for correcting the projection screen are determined. This allows for rapid and accurate correction of the projection screen. Specifically, when constructing the specific projection scene, a pre-constructed image with specific markers can be projected onto the projection screen using a projection device, ensuring the projection screen covers the entire screen area. Thus, based on the vertices of the projection screen in the captured image and nearby specific markers, the accurate coordinates of the projection screen in the projection device's coordinate system required for projection screen correction can be determined using only one captured image. This reduces the difficulty of projection screen correction and improves its efficiency and accuracy.

[0037] In this embodiment, the projection image correction method can be applied to projection devices and camera devices that are electrically or communicatively connected to each other. It can also be directly applied to projection devices that include a camera device. For projection devices requiring projection image correction, the projection image correction function provided by the method of this application can be directly integrated into the projection device, or it can run on the projection device in the form of a software development kit (SDK). In other embodiments, the camera device can also be a camera device of a terminal device, such as a mobile phone camera, and the projection image correction function provided by the method of this application can be directly integrated into the terminal device.

[0038] The following will take the application of the projection image correction method to a projection device including a camera as an example. To facilitate a clear and complete description of the embodiments of this application, the specific process of the projection image correction method will be described below with reference to Figure 2. As shown in Figure 2, this is a flowchart of the projection image correction method provided by the embodiments of this application. Depending on different needs, the order of the steps in this flowchart can be changed, and some steps can be omitted.

[0039] Step S1: Acquire the captured image.

[0040] In one embodiment, the method for correcting the projected image essentially ensures that the projection device can accurately project the image onto the projection screen area and maintain alignment between the projected image and the boundary of the projection screen area. To this end, a key step in correcting the projected image is determining the precise position of the projection screen area in the coordinate system of the projection device's display chip, for example, the coordinates of the vertices of the projection screen area. The vertices of the projection screen area include the upper-left, upper-right, lower-left, and lower-right vertices. In this way, the projection device can intelligently adjust the size and orientation of the projected image to precisely align the vertices of the projected image with the vertices of the projection screen area, thereby achieving accurate correction of the projected image.

[0041] In short, the core of projection image calibration lies in enabling the projection device to "know" the location of the projection screen area. Therefore, by setting a specific preset image, a reference frame can be provided for the projection device, helping it determine the location of the projection screen area in its own coordinate system (such as the coordinate system of the projection device's display chip).

[0042] Specifically, the preset image may contain specific markers, the position, shape, and size of which are pre-defined. By photographing the projection screen area onto which the preset image is projected, a captured image containing both the projected image and the vertices of the projection screen area can be obtained. Based on the relationship between the projected image and the projection screen in the captured image, especially the relative positions of the specific markers in the preset image and the vertices of the projection screen area, key information for correcting the projected image can be obtained.

[0043] In one embodiment, the captured image is obtained when a projection device projects a preset image. The preset image may be a pre-constructed specific pattern diagram, and may include positioning marks and correction marks. For example, the specific marks in the preset image include positioning marks and correction marks.

[0044] In one embodiment, the positioning marker may be located in the central area of ​​a preset image. The positioning marker can be used to locate the preset image, for example, to locate the area where the preset image is located in a captured image. The positioning marker includes one or more marker graphics, such as, but not limited to, dot arrays, checkerboard patterns, Aruco QR codes, etc.

[0045] In one embodiment, the correction mark can be located in the boundary area of ​​a preset image, and the correction mark is set around the positioning mark. The correction mark can be used for precision correction. For example, by determining the relative position of the correction mark and the vertex of the projection screen area, the precision correction of the vertex position of the projection screen area in the coordinate system of the display chip of the projection device can be achieved, eliminating errors caused by camera distortion and unevenness of the screen.

[0046] The correction markers include one or more marker shapes, such as, but not limited to, cross markers, triangle markers, and pentagram markers. The coordinates of the correction markers in the preset image are known; for example, the coordinates of the correction markers can be the coordinates of the center point of the corresponding marker shape. For instance, if the correction marker is a cross marker "+", the intersection of the two lines in the cross marker "+" can be taken as the center point of the cross marker, and the coordinates of this center point can be used as the coordinates of the corresponding cross marker in the preset image.

[0047] Furthermore, since the coordinate system of the projection device's display chip can precisely locate every pixel on the projected image, and when the projection device projects a preset image, the coordinate system of the projection device's display chip is consistent with the coordinate system corresponding to the preset image in the projection device's viewing angle, the coordinates of the correction mark in the projected image under the coordinate system of the projection device's display chip are known. For example, the coordinates of the correction mark in the projected image under the coordinate system of the projection device's display chip are equal to the coordinates of the correction mark under the coordinate system corresponding to the preset image.

[0048] For example, Figure 3 shows an example of a preset image provided in an embodiment of this application, where the marker graphics within the dashed frame represent positioning markers, and the marker graphics outside the dashed frame represent correction markers. Figure 4 shows an example of a preset image provided in an embodiment of this application, where the marker graphics within the dashed frame represent positioning markers, and the marker graphics outside the dashed frame represent correction markers.

[0049] By setting a preset image with positioning and correction marks, the requirements for the shooting environment of the captured image can be reduced. For example, the preset image can be applied to environments with complex lighting, camera distortion, uneven screen, etc., which makes it easier to achieve accurate correction of the projected image based on a captured image in subsequent processes.

[0050] In one embodiment, a preset image can cover the projection screen area, so that the correction marks of the preset image can surround the vertices of the projection screen area, making it easier to determine the relative positions of the correction marks in the preset image and the vertices of the projection screen area.

[0051] For example, Figure 5 shows an example of a captured image provided in an embodiment of this application, wherein a preset image covers the projection screen area, and the correction marks (e.g., triangle marks) of the preset image surround the vertices of the projection screen area.

[0052] In one embodiment, to determine the coordinates of the vertices of the projection screen area in the coordinate system of the display chip of the projection device, the coordinates of the vertices of the projection screen area in the coordinate system corresponding to the captured image can be determined first. For example, the region where the preset image is located can be determined first based on the position of the vertices of the preset image in the captured image, then the projection screen area can be determined within the region where the preset image is located, and finally the position of the vertices of the projection screen area in the captured image can be determined.

[0053] For example, the following describes the process of determining the position of the vertex of the projection screen area in the captured image, with reference to Figure 6. Depending on different needs, the order of the steps in this flowchart can be changed, and some steps can be omitted.

[0054] Step S11: Determine the coordinates of the first vertex of the preset image in the coordinate system of the captured image, and determine the corresponding area of ​​the preset image in the captured image based on the coordinates of the first vertex.

[0055] In one embodiment, the preset image can be located in the captured image based on the positioning marks in the preset image using image recognition technology, thereby determining the first vertex coordinates of the preset image's vertices in the captured image coordinate system based on the located preset image.

[0056] In one example, image recognition technology includes, but is not limited to, object recognition technology and template matching technology. The vertices of the preset image include the top-left vertex, top-right vertex, bottom-left vertex, and bottom-right vertex, where each of these four vertices has a corresponding first vertex coordinate. The image coordinate system can be a coordinate system with the bottom-left corner of the image as the origin, the longer side of the image as the horizontal axis, and the shorter side of the image as the vertical axis. The unit length in the image coordinate system can be the length of one pixel.

[0057] In one embodiment, when determining the region corresponding to the preset image in the captured image based on the coordinates of the first vertex, the region enclosed by the coordinates of the four vertices corresponding to the four vertices of the preset image can be used as the region corresponding to the preset image in the captured image.

[0058] Step S12: Determine the projection screen area within the region corresponding to the preset image in the captured image, and determine the second vertex coordinates of the vertex of the projection screen area in the coordinate system corresponding to the captured image.

[0059] In one embodiment, since the preset image covers the projection screen area, the projection screen area can be determined within the area corresponding to the preset image in the captured image.

[0060] In one example, image recognition technology can be used to extract the four boundary lines corresponding to the four boundaries of the projection screen area within the area corresponding to the preset image in the captured image, determine the projection screen area based on the area enclosed by the four boundary lines, and determine the vertices of the projection screen area based on the intersection of the four boundary lines.

[0061] The projection screen area has four boundaries: left, right, top, and bottom. Each boundary corresponds to a boundary line, and the intersection of any two boundaries is considered a vertex. The vertices of the projection screen area include the top-left, top-right, bottom-left, and bottom-right vertices.

[0062] Through the above embodiments, the region corresponding to the preset image in the captured image can be accurately extracted based on image analysis technology by using specific markers (such as positioning markers) in the preset image, and the coordinates of the vertices of the projection screen area in the coordinate system corresponding to the captured image can be determined based on this region, providing a basis for subsequently determining the coordinates of the vertices of the projection screen area in the coordinate system of the display chip of the projection device.

[0063] Furthermore, when the projection device projects a preset image, the coordinates of the vertices of the preset image in the coordinate system of the projection device's display chip are known. For example, the coordinates of a vertex of the preset image in the coordinate system of the projection device's display chip are equal to its coordinates in the coordinate system of the preset image itself. After determining the coordinates of the first vertex of the four vertices of the preset image in the coordinate system of the captured image, the transformation relationship between the coordinate system of the projection device's display chip and the coordinate system of the captured image can be determined based on the two sets of coordinates of the vertices of the preset image in both the captured image and the projection device's display chip coordinate systems.

[0064] Step S2: Determine the image correction parameters based on the positioning marks and correction marks, and correct the projected image based on the image correction parameters.

[0065] In one embodiment, after determining the region corresponding to the preset image in the captured image based on the positioning markers, and determining the coordinates of the vertices of the projection screen region in the coordinate system corresponding to the captured image within that region, image correction parameters can be further determined based on correction markers near the vertices of the projection screen region. Specifically, the image correction parameters may include the coordinates of the vertices of the projection screen region in the coordinate system of the display chip of the projection device.

[0066] In one embodiment, when determining image correction parameters, multiple nearest neighbor markers of the vertices of the projection screen area can be determined from the correction markers; a preset number of nearest neighbor markers with the largest enclosing area can be selected from the multiple nearest neighbor markers, and the selected preset number of nearest neighbor markers can be used as multiple first markers; the image correction parameters can be determined based on the multiple first markers.

[0067] In one embodiment, the distance between the correction mark and the vertex of the projection screen area can be determined based on the coordinates of the correction mark in the coordinate system corresponding to the captured image and the second vertex coordinates of the vertex of the projection screen area in the coordinate system corresponding to the captured image, and multiple nearest neighbor marks can be determined based on the distance between the correction mark and the vertex of the projection screen area.

[0068] Taking the top-left vertex of the projection screen area as an example, the Euclidean distance between the top-left vertex and each correction marker in the coordinate system corresponding to the captured image can be determined. Based on the Euclidean distance, multiple nearest neighbor markers of the top-left vertex can be determined. These multiple nearest neighbor markers can be located around the top-left vertex, and can include nearest neighbor markers located within the projection screen area or outside the projection screen area.

[0069] To determine the image correction parameters, a preset number of nearest neighbor markers that lie in the same plane as the vertices of the projection screen area can be selected, such as a preset number of nearest neighbor markers located within the projection screen area. The preset number can be an integer greater than or equal to 3.

[0070] Specifically, it is possible to traverse the enclosed areas (e.g., the triangular area enclosed by 3 nearest neighbor tags) of each preset number of nearest neighbor tags in multiple nearest neighbor tags, select the enclosed area that is located within the projection screen area and has the largest area from the enclosed areas, and use the preset number of nearest neighbor tags corresponding to the selected enclosed areas as multiple first tags.

[0071] In one embodiment, after determining multiple first markers, the coordinates of the first markers in the coordinate system corresponding to the captured image can be determined. Then, based on the transformation relationship between the coordinate system corresponding to the captured image and the coordinate system of the projection device's display chip, the coordinates of the first markers in the projection device's display chip coordinate system can be determined. Next, the positional relationship between the coordinates of the first markers in the coordinate system corresponding to the captured image and the coordinates of the vertices of the projection screen area can be determined. Finally, this positional relationship is applied to the projection device's display chip coordinate system, and by combining this positional relationship with the coordinates of the first markers in the projection device's display chip coordinate system, image correction parameters for correcting the projected image to the projection screen area can be determined.

[0072] For example, the process of determining image correction parameters is described below with reference to Figure 7. Depending on different needs, the order of the steps in this flowchart can be changed, and some steps can be omitted.

[0073] Step S21: When determining image correction parameters based on multiple first markers, the accuracy correction coefficient can be determined based on the coordinates of the multiple first markers in the coordinate system corresponding to the captured image and the coordinates of the second vertex.

[0074] In one embodiment, the second vertex coordinates represent the coordinates of a vertex in the projection screen area within the coordinate system corresponding to the captured image. The accuracy correction coefficient may include coordinate coefficients of the second vertex coordinates in the marker space coordinate system corresponding to multiple first markers. The accuracy correction coefficient can be used to indicate the positional relationship between the multiple first markers and the vertices of the projection screen area.

[0075] Specifically, taking the top-left vertex of the projection screen area as an example, the top-left vertex can be used as the centroid of the area enclosed by multiple first markers. Then, based on the coordinates of the multiple first markers in the coordinate system corresponding to the captured image and the coordinates of the second vertex, the centroid coefficient of the area enclosed by the multiple first markers can be determined, and this centroid coefficient can be used as the coordinate coefficient of the second vertex in the marker space coordinate system corresponding to the multiple first markers.

[0076] For example, the formula used to determine the accuracy correction coefficient can be expressed as: m A =αm i +βm j +γm k

[0077] Where, m A This represents the coordinates of the second vertex of the projection screen area (e.g., the top left vertex), m. i m represents the coordinates of the first marker i in the coordinate system corresponding to the captured image. j This represents the coordinates of the first marker j in the coordinate system corresponding to the captured image, m. k The coordinates of the first marker k in the coordinate system corresponding to the captured image are represented by α, β, and γ, which represent the accuracy correction coefficients.

[0078] Step S22: Determine the image correction parameters based on the accuracy correction coefficient and the coordinates of multiple first marks in the coordinate system of the projection device display chip.

[0079] In one embodiment, the accuracy correction coefficient can be applied to the coordinate system of the projection device display chip to determine the coordinates of the vertex of the projection screen area in the coordinate system of the projection device display chip as image correction parameters, based on the positional relationship between the multiple first marks and the vertices of the projection screen area, and the coordinates of the multiple first marks in the coordinate system of the projection device display chip.

[0080] Specifically, taking the top left vertex as the vertex of the projection screen area as an example, the top left vertex can be used as the centroid of the area enclosed by multiple first marks, and the precision correction coefficient can be used as the centroid coefficient of the area enclosed by multiple first marks. The centroid coordinates of the centroid are determined based on the coordinates of multiple first marks in the coordinate system of the projection device display chip and the centroid coefficient, and the centroid coordinates are used as the coordinates of the top left vertex in the coordinate system of the projection device display chip.

[0081] For example, the formula used to determine the image correction parameters can be expressed as: S A =αs i +βs j +γs k ,

[0082] Among them, S A This represents the image correction parameter s corresponding to the vertex (e.g., the top left vertex) of the projection screen area. i This represents the coordinates of the first marker i in the coordinate system of the display chip in the projection device, s j This represents the coordinates of the first marker j in the coordinate system of the display chip in the projection device, s k The coordinates of the first marker k in the coordinate system of the display chip of the projection device are represented; α, β, and γ represent the accuracy correction coefficients.

[0083] Through the above embodiments, the coordinates of the vertex of the projection screen area in the coordinate system of the projection device display chip can be determined based on the positional relationship between the multiple first marks near the vertex of the projection screen area and the vertex of the projection screen area, as well as the coordinates of the multiple first marks in the coordinate system of the projection device display chip.

[0084] In one embodiment, when correcting the projected image according to image correction parameters, the projection device can be controlled to determine the vertex coordinates of the image to be projected according to the image correction parameters, so that the projected image corresponding to the image to be projected is aligned with the projection screen area.

[0085] Specifically, since the image correction parameters indicate the vertex position of the projection screen area, the image correction parameters can be used as the vertex coordinates of the image to be projected. The projection device is then controlled to project the image to be projected according to the vertex coordinates of the image to be projected, so that the image to be projected is projected onto the projection screen area, thereby aligning the projected image corresponding to the image to be projected with the projection screen area.

[0086] For example, the image correction parameters corresponding to the top left vertex of the projection screen area can be used as the vertex coordinates of the top left vertex of the image to be projected, the image correction parameters corresponding to the top right vertex of the projection screen area can be used as the vertex coordinates of the top right vertex of the image to be projected, the image correction parameters corresponding to the bottom left vertex of the projection screen area can be used as the vertex coordinates of the bottom left vertex of the image to be projected, and the image correction parameters corresponding to the bottom right vertex of the projection screen area can be used as the vertex coordinates of the bottom right vertex of the image to be projected. In this way, the image to be projected can be projected onto the projection screen area.

[0087] In one embodiment, if the projection device is a short-throw projection device, a wide-angle lens is usually required to achieve a larger projection image due to the short projection distance. If the projected image is projected onto an uneven screen, severe distortion will occur. In this case, simply using the image correction parameters corresponding to the vertices of the projection screen area in the above method to correct the projected image may not achieve the desired effect. Further distortion correction (dewarping) can be performed on the corrected projected image.

[0088] In one embodiment, distortion correction of the projected image after projection correction may include: determining multiple boundary points of the projection screen area, and determining the image correction parameters corresponding to each of the multiple boundary points according to the correction marks; and performing distortion correction on the projected image after projection correction according to the image correction parameters corresponding to each boundary point.

[0089] Specifically, multiple boundary points can be determined first at each boundary of the projection screen area. For example, multiple (e.g., 5) equally divided points can be taken as boundary points at each boundary. Then, multiple correction markers are determined near each boundary point as second markers, using a method similar to that used for determining the first markers. Next, based on the positional relationship between the second markers and each boundary point in the coordinate system corresponding to the captured image, the accuracy correction coefficient for each boundary point is determined. Then, based on the accuracy correction coefficient for each boundary point and the coordinates of the second markers in the coordinate system of the projection device's display chip, the image correction parameters for each boundary point are determined; for example, the coordinates of each boundary point in the coordinate system of the projection device's display chip. Finally, the projection device can be controlled to determine the coordinates of the boundary points of the image to be projected based on the image correction parameters, ensuring that the projected image is aligned with the projection screen area.

[0090] The above embodiments can effectively solve the problem of projection image distortion caused by short-throw machines or uneven screens.

[0091] The projection screen correction method provided in this application constructs a specific projection scene and captures an image of that scene in a single photograph. Based on the vertices of the projection screen and specific markers in the image, image correction parameters are determined to correct the projection screen. This allows for rapid and accurate correction of the projection screen. Specifically, when constructing the projection scene, a pre-constructed image with specific markers can be projected onto the projection screen using a projection device, ensuring the image covers the entire screen area. This allows the accurate coordinates of the projection screen in the projection device's coordinate system to be determined from just one image, based on the vertices of the projection screen and nearby markers in the captured image. This reduces the difficulty of projection screen correction and improves its efficiency and accuracy.

[0092] It should be understood that although the steps in the flowcharts of Figures 2, 6, and 7 are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some of the steps in Figures 2, 6, and 7 may include multiple steps or stages, which are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps.

[0093] In some embodiments, the above-described projection image correction method can be implemented as a computer program, which can run on the projection device shown in FIG8. The architecture of the hardware device for implementing the projection image correction method will be described below with reference to FIG8.

[0094] It should be understood that the embodiments are for illustrative purposes only and are not limited to this structure in the scope of the patent application.

[0095] Referring to Figure 8, it is a schematic diagram of the structure of the projection device provided in the embodiment of this application.

[0096] The projection device 200 includes a projection unit 210 and a drive unit 220 for driving the projection unit 210. The projection unit 210 can form an optical image and project the optical image onto an imaging medium SC.

[0097] The projection unit 210 includes a light source unit 211, a light modulator 212, and an optical system 213. The driving unit 220 includes a light source driving unit 221 and a light modulator driving unit 222.

[0098] The light source unit 211 may include solid-state light sources such as light-emitting diodes (LEDs), lasers, and pump lamps. The light source unit 211 may include optical elements such as lenses and polarizers for improving the optical characteristics of the projected light, as well as dimming elements for adjusting the luminous flux.

[0099] The light source driving unit 221 can control the operation of the light source in the light source unit 211, including turning it on and off, according to the instructions of the control unit 250.

[0100] The light modulator 212 includes a display panel 215, which can be a transmissive liquid crystal display (LCD), a reflective liquid crystal on silicon (LCOS), or a digital micromirror device (DMD).

[0101] The optical modulator 212 is driven by the optical modulator driver unit 222, which is connected to the image processing unit 245.

[0102] The image processing unit 245 inputs image data to the light modulator driving unit 222. The light modulator driving unit 222 converts the input image data into a data signal suitable for the operation of the display panel 215. Based on the converted data signal, the light modulator driving unit 222 applies voltage to each pixel of each display panel 215 and draws an image on the display panel 215.

[0103] The optical system 213 includes a lens or mirror that causes the incident image light PLA to form an image on the imaging medium SC. The optical system 213 may also include a zoom mechanism that magnifies or reduces the image projected onto the imaging medium SC and a focus adjustment mechanism that performs focus adjustment.

[0104] The projection device 200 also includes an operation unit 231, a signal receiving unit 233, an input interface 235, a storage unit 237, a data interface 241, an interface unit 242, a frame memory 243, an image processing unit 245, and a control unit 250. The input interface 235, storage unit 237, data interface 241, interface unit 242, image processing unit 245, and control unit 250 can communicate with each other via an internal bus 207.

[0105] The operation unit 231 can generate corresponding operation signals based on the operation of various buttons and switches on the surface of the projection device 200 housing, and output them to the input interface 235. The input interface 235 includes circuitry that outputs the operation signals input from the operation unit 231 to the control unit 250.

[0106] After receiving signals (such as infrared signals or Bluetooth signals) sent from the control device 5 (such as a remote control), the signal receiving unit 233 can decode the received signals to generate corresponding operation signals. The signal receiving unit 233 outputs the generated operation signals to the input interface 235. The input interface 235 outputs the received operation signals to the control unit 250.

[0107] Storage unit 237 may be a magnetic recording device such as a hard disk drive (HDD), or a storage device using semiconductor storage elements such as flash memory. Storage unit 237 stores programs executed by control unit 250, data processed by control unit 250, image data, etc.

[0108] Data interface 241 includes a connector and interface circuitry, enabling wired connection with other electronic devices 100. Data interface 241 can also be a communication interface for communicating with other electronic devices 100. Data interface 241 receives image data, sound data, etc., from other electronic devices 100. In this embodiment, the image data can be content images.

[0109] Interface unit 242 is a communication interface for communicating with other electronic devices 100 according to the Ethernet standard. Interface unit 242 includes a connector and interface circuitry for processing signals transmitted by the connector. Interface unit 242 is an interface substrate including the connector and interface circuitry and is connected to the main substrate of control unit 250, which is a substrate on which processor 253 and other components are mounted. The connector and interface circuitry constituting interface unit 242 are mounted on the main substrate of control unit 250. Interface unit 242 can receive setting information or instruction information transmitted by other electronic devices 100.

[0110] The control unit 250 includes a memory 251 and a processor 253.

[0111] Memory 251 is a storage device that non-volatilely stores programs and data executed by processor 253. Memory 251 is composed of semiconductor storage elements such as magnetic storage devices, flash read-only memory (ROM), or other types of non-volatile storage devices. Memory 251 may also include random access memory (RAM) that constitutes the working area of ​​processor 253. Memory 251 stores data processed by control unit 250 and control programs executed by processor 253.

[0112] The processor 253 can be a single processor or a combination of multiple processor groups. The processor 253 executes a control program to control various parts of the projection device 200. For example, the processor 253 performs corresponding interactive projection screen correction based on the operation signal generated by the operation unit 231, and outputs the parameters used in the interactive projection screen correction (such as parameters for keystone correction of the image) to the image processing unit 245. Furthermore, the processor 253 can control the light source in the light source unit 211 to turn on, off, or adjust its brightness by controlling the light source drive unit 221.

[0113] The image processing unit 245 and the frame memory 243 can be constructed from integrated circuits. Integrated circuits include large-scale integrated circuits (LSI), application-specific integrated circuits (ASIC), and programmable logic devices (PLD), where PLD may include field-programmable gate arrays (FPGA). Integrated circuits may also include a portion of analog circuitry, or a combination of a processor and integrated circuits. Combinations of processors and integrated circuits are referred to as microcontroller units (MCU), system-on-chips (SoC), system LSIs, chipsets, etc.

[0114] The image processing unit 245 can store the image data received from the data interface 241 in the frame memory 243. The frame memory 243 includes multiple memory banks, each containing storage capacity for writing one frame of image data. The frame memory 243 can be constructed from synchronous dynamic random access memory (SDRAM) or dynamic random access memory (DRAM).

[0115] The image processing unit 245 can perform interactive projection image correction on the image data stored in the frame memory 243, including resolution conversion, size adjustment, distortion correction, shape correction, digital zoom, image tone adjustment, and image brightness adjustment.

[0116] The image processing unit 245 can also convert the input frame frequency of the vertical synchronization signal into a drawing frequency and generate a vertical synchronization signal with a drawing frequency. The generated vertical synchronization signal is called the output synchronization signal. The image processing unit 245 then outputs the above-mentioned output synchronization signal to the optical modulator driver unit 222.

[0117] In some embodiments of this application, a computer-readable storage medium is provided, storing a computer program that is loaded by a processor, causing the processor to execute the steps of the data migration method described above. The steps of this data migration method may be steps from the projection image correction methods of the various embodiments described above.

[0118] The above description is merely a preferred embodiment of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features disclosed in this disclosure that have similar functions.

[0119] Furthermore, while the operations are described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in a sequential order. In certain environments, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0120] Although the subject matter has been described using language specific to the method's logical actions, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims. Regarding the apparatus in the above embodiments, the specific manner in which the various modules perform their operations has been described in detail in the embodiments relating to the method, and will not be elaborated upon here.

Claims

1. A method for correcting a projected image, wherein, include: Acquire a captured image, which is captured when a preset image is projected by a projection device; wherein the preset image includes a positioning mark and a correction mark; the positioning mark is used to position the preset image, and the correction mark is used to perform accuracy correction; Image correction parameters are determined based on the positioning marks and the correction marks, and the projected image is corrected based on the image correction parameters.

2. The projection image correction method according to claim 1, wherein, The positioning marker is located in the central area of ​​the preset image, and the positioning marker includes one or more marker graphics.

3. The projection image correction method according to claim 1, wherein, The correction mark is located in the boundary area of ​​the preset image, and the correction mark includes one or more mark graphics.

4. The projection image correction method according to claim 1, wherein, The correction markers are positioned around the positioning markers.

5. The projection image correction method according to claim 1, wherein, The preset image covers the projection screen area.

6. The projection image correction method according to claim 5, wherein, Before determining the image correction parameters, the method further includes: Determine the first vertex coordinates of the vertex of the preset image in the coordinate system of the captured image, and determine the region of the preset image in the captured image based on the first vertex coordinates; The projection screen area is determined within the area corresponding to the preset image in the captured image, and the second vertex coordinates of the vertex of the projection screen area in the coordinate system corresponding to the captured image are determined.

7. The projection image correction method according to claim 6, wherein, Determining the projection screen area within the corresponding region of the preset image in the captured image includes: Using image recognition technology, four boundary lines corresponding to the four boundaries of the projection screen area are extracted from the area corresponding to the preset image in the captured image. The projection screen area is determined based on the region enclosed by the four boundary lines, and the vertices of the projection screen area are determined based on the intersection of the four boundary lines.

8. The projection image correction method according to claim 5, wherein, The method for determining the image correction parameters includes: Determine multiple nearest neighbor markers of the vertices of the projection screen area from the correction markers; From the plurality of nearest neighbor markers, select a preset number of nearest neighbor markers with the largest enclosing area, and use the selected preset number of nearest neighbor markers as a plurality of first markers; The image correction parameters are determined based on the plurality of first markers.

9. The projection image correction method according to claim 8, wherein, The nearest neighbor markers for determining the vertices of the projection screen area from the correction markers include: The distance between the correction mark and the vertex of the projection screen area is determined based on the coordinates of the correction mark in the coordinate system corresponding to the captured image, and the second vertex coordinates of the vertex of the projection screen area in the coordinate system corresponding to the captured image. The plurality of nearest neighbor markers are determined based on the distance between the correction marker and the vertex of the projection screen area.

10. The projection image correction method according to claim 8, wherein, From the plurality of nearest neighbor markers, a preset number of nearest neighbor markers with the largest enclosing region are selected, and the selected preset number of nearest neighbor markers are used as a plurality of first markers, including: Traverse the enclosed areas formed by a preset number of nearest neighbor markers among the plurality of nearest neighbor markers, select the enclosed area with the largest area within the projection screen area from the enclosed areas, and use the preset number of nearest neighbor markers corresponding to the selected enclosed area as the plurality of first markers.

11. The projection image correction method according to claim 8, wherein, Determining the image correction parameters based on the plurality of first markers includes: The accuracy correction coefficient is determined based on the coordinates of the plurality of first markers in the coordinate system corresponding to the captured image and the coordinates of the second vertex; wherein, the second vertex coordinates represent the coordinates of the vertex of the projection screen area in the coordinate system corresponding to the captured image; The image correction parameters are determined based on the accuracy correction coefficient and the coordinates of the plurality of first marks in the coordinate system of the projection device display chip.

12. The projection image correction method according to claim 11, wherein, The accuracy correction coefficient includes the coordinate coefficients of the second vertex coordinates in the mark space coordinate system corresponding to the plurality of first marks, and the accuracy correction coefficient is used to indicate the positional relationship between the plurality of first marks and the vertices of the projection screen area.

13. The projection image correction method according to claim 11, wherein, The image correction parameters are determined based on the accuracy correction coefficients and the coordinates of the plurality of first markers in the coordinate system of the projection device display chip, including: The accuracy correction coefficient is applied to the coordinate system of the projection device display chip. Based on the positional relationship between the plurality of first marks and the vertices of the projection screen area, and the coordinates of the plurality of first marks in the coordinate system of the projection device display chip, the coordinates of the vertices of the projection screen area in the coordinate system of the projection device display chip are determined as image correction parameters.

14. The projection image correction method according to claim 5, wherein, The vertices of the projection screen area include the upper left vertex, upper right vertex, lower left vertex, and lower right vertex of the projection screen area.

15. The projection image correction method according to claim 5, wherein, The step of correcting the projected image according to the image correction parameters includes: The projection device is controlled to determine the vertex coordinates of the image to be projected based on the image correction parameters, so that the projected image corresponding to the image to be projected is aligned with the projection screen area.

16. The projection image correction method according to claim 15, wherein, The method further includes: The image correction parameters are used as the vertex coordinates of the image to be projected. The projection device is controlled to project the image to be projected according to the vertex coordinates of the image to be projected, so that the image to be projected is projected onto the projection screen area, thereby aligning the projected image corresponding to the image to be projected with the projection screen area.

17. The projection image correction method according to claim 5, wherein, The method further includes: Determine multiple boundary points of the projection screen area, and determine the image correction parameters corresponding to each of the multiple boundary points according to the correction marks; The distortion of the projected image is corrected based on the image correction parameters corresponding to each boundary point.

18. The projection image correction method according to claim 17, wherein, The method further includes: In each boundary of the projection screen area, the plurality of boundary points are determined, and in the vicinity of each boundary point, a plurality of correction marks are determined as second marks; Based on the positional relationship between the second mark and each boundary point in the coordinate system corresponding to the captured image, determine the accuracy correction coefficient corresponding to each boundary point; Based on the precision correction coefficient corresponding to each boundary point and the coordinates of the second mark in the coordinate system of the display chip of the projection device, determine the image correction parameters corresponding to each boundary point; The projection device is controlled to determine the coordinates of each boundary point of the image to be projected according to the image correction parameters, so that the projected image corresponding to the image to be projected is aligned with the projection screen area.

19. A projection device, wherein, The projection device includes: One or more processors; The memory; and one or more applications, wherein the one or more applications are stored in the memory and configured to be executed by the processor to implement the projection image correction method of any one of claims 1 to 18.

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