WO2022206527A1 - 投影图像的校正方法及激光投影设备 - Google Patents

投影图像的校正方法及激光投影设备 Download PDF

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Publication number
WO2022206527A1
WO2022206527A1 PCT/CN2022/082627 CN2022082627W WO2022206527A1 WO 2022206527 A1 WO2022206527 A1 WO 2022206527A1 CN 2022082627 W CN2022082627 W CN 2022082627W WO 2022206527 A1 WO2022206527 A1 WO 2022206527A1
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Prior art keywords
target
projection
projection position
initial
image
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PCT/CN2022/082627
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English (en)
French (fr)
Inventor
张冬冬
唐甜甜
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青岛海信激光显示股份有限公司
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Publication of WO2022206527A1 publication Critical patent/WO2022206527A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3179—Video signal processing therefor
    • H04N9/3185—Geometric adjustment, e.g. keystone or convergence
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof
    • H04N9/315—Modulator illumination systems
    • H04N9/3161—Modulator illumination systems using laser light sources

Definitions

  • the present disclosure relates to the field of projection display, and in particular, to a correction method of a projected image and a laser projection device.
  • laser projection equipment can project and display projected images on a projection screen.
  • the projection lens of the laser projection device is distorted, the projected image projected and displayed by the laser projection device on the projection screen will be deformed, resulting in poor display effect of the displayed projected image.
  • a method for calibrating a projected image which is applied to a laser projection device, and the method includes:
  • a target image is displayed on the projection screen, and the target image includes a main picture and a plurality of characteristic graphics surrounding the main picture, and the color of each of the characteristic graphics is the same as the color of the target image except the main picture.
  • the background color of the area outside is different;
  • For each of the feature patterns determine the first target projection position of the feature pattern on the projection screen according to the perspective transformation coefficient of the camera and the shooting position of the feature pattern in the captured image;
  • the projection position of the projected image is corrected according to the first target projection position of the plurality of feature patterns and the second target projection position of the reference point.
  • a laser projection device for:
  • a target image is displayed on the projection screen, and the target image includes a main picture and a plurality of characteristic graphics surrounding the main picture, and the color of each of the characteristic graphics is the same as the color of the target image except the main picture.
  • the background color of the area outside is different;
  • For each of the feature patterns determine the first target projection position of the feature pattern on the projection screen according to the perspective transformation coefficient of the camera and the shooting position of the feature pattern in the captured image;
  • the projection position of the projected image is corrected according to the first target projection position of the plurality of feature patterns and the second target projection position of the reference point.
  • FIG. 1 is a flowchart of a method for correcting a projected image provided by an embodiment of the present disclosure
  • FIG. 2 is a schematic structural diagram of a laser projection device provided by an embodiment of the present disclosure
  • FIG. 3 is a schematic structural diagram of a target image provided by an embodiment of the present disclosure.
  • FIG. 4 is a flowchart of a method for correcting a projected image provided by an embodiment of the present disclosure
  • FIG. 5 is a schematic diagram of a characteristic graph provided by an embodiment of the present disclosure.
  • FIG. 6 is a schematic diagram of deformation of a projection image provided by the related art.
  • FIG. 7 is a schematic diagram of deformation of another projection image provided by the related art.
  • FIG. 8 is a schematic diagram of another projection image deformation provided by the related art.
  • FIG. 9 is a schematic structural diagram of another laser projection device provided by an embodiment of the present disclosure.
  • FIG. 1 is a flowchart of a method for correcting a projected image provided by an embodiment of the present disclosure.
  • the correction method can be applied to laser projection equipment. As shown in Figure 1, the method may include:
  • Step 101 In response to the correction instruction, display the target image on the projection screen.
  • the laser projection apparatus 10 can project and display the target image on the projection screen 20 in response to the correction instruction.
  • the target image 30 may include a main screen 301 and a plurality of characteristic graphics (eg, characteristic graphics 302 a , 302 b and 302 c ) surrounding the main screen 301 .
  • the color of each feature pattern is different from the background color of the area other than the main screen 301 in the target image 30.
  • the color of each feature graphic may be black, and the background color of the area other than the main screen 301 in the target image 30 may be white.
  • the laser projection equipment can keep the playback state of the main screen in the target image unchanged, thereby realizing the correction of the projection position of the projected image while ensuring the continuity of the main screen playback, thereby ensuring Continuity of user viewing.
  • Step 102 Acquire a photographed image obtained by photographing the projection screen by the camera.
  • the laser projection apparatus 10 may be provided with a camera 40 . After the laser projection device projects and displays the target image on the projection screen, it can send a shooting instruction to the camera. After receiving the photographing instruction, the camera can photograph the projection screen 20 to obtain a photographed image, and send the photographed image to the laser projection device 10, so that the laser projection device 10 can obtain the photographed image.
  • the camera can be independent of the laser projection device, and the user can control the camera to capture the projection screen to obtain a captured image, and control the camera to send the captured image to the laser projection device, and the laser projection device can obtain the captured image .
  • Step 103 For each feature pattern, determine the first target projection position of the feature pattern on the projection screen according to the perspective transformation coefficient of the camera and the shooting position of the feature pattern in the shot image.
  • the laser projection device After the laser projection device acquires the captured image, for each feature image, the laser projection device can determine the first position of the feature image on the projection screen according to the perspective transformation coefficient of the camera and the shooting position of the feature image in the captured image. A target projection position.
  • the perspective transformation coefficient can transform the position of any point on the projection screen into the position in the captured image, that is, the perspective transformation coefficient is the coefficient of variation between the coordinate system of the projection screen and the coordinate system of the captured image.
  • the perspective transformation coefficient is related to the shooting position of the camera, the distance between the camera and the projection screen, and the resolution of the camera.
  • the projection screen may be polygonal, eg, rectangular.
  • Step 104 Determine the second target projection position of the reference point on the projection screen according to the perspective transformation coefficient and the shooting position of the reference point in the main screen in the shot image.
  • the laser projection device can also determine the second target projection position of the reference point on the projection screen according to the perspective transformation coefficient of the camera and the shooting position of the reference point in the main screen in the shot image.
  • the reference point may be located on the boundary of the main picture, or the reference point may be the center point of the main picture.
  • Step 105 Correct the projection position of the projected image according to the first target projection position of the plurality of feature patterns and the second target projection position of the reference point.
  • the laser projection device may, according to the first target projection position of the plurality of feature patterns and the second target projection position of the reference point, determine the target projection position of the reference point. Correct the projection position of the projected image.
  • the laser projection device can determine that the target vertex of the target image is on the projection screen according to the first target projection position of the target feature graph in the plurality of feature graphs and the second target projection position of the reference point.
  • the projection position of the projected image can be corrected according to the third target projection position of the target vertex and the first initial projection position of the target vertex on the projection screen.
  • the projection position of the projection image may be adjusted based on the difference between the third target projection position and the first initial projection position, so as to realize the correction of the projection position.
  • the first initial projection position of the target vertex may be the position of the target vertex on the projection screen when the projected image is not deformed.
  • the embodiments of the present disclosure provide a method for calibrating a projected image, because the method can determine the characteristic pattern according to the perspective transformation coefficient, the shooting position of the feature pattern, and the shooting position of the reference point in the main screen.
  • the first target projection position and the second target projection position of the reference point The first target projection position and the second target projection position of the reference point.
  • the projection position of the projected image may be corrected according to the first target projection position of the plurality of feature patterns and the second target projection position of the reference point. Therefore, even if the projection lens of the laser projection device is distorted or the laser projection device is displaced, the projected image displayed on the projection screen will not be deformed, thereby ensuring a better display effect of the projected image.
  • the target image displayed on the projection screen includes the main image during the process of calibrating the projected image
  • the continuous playback of the main image can be ensured, and the continuous playback of the main image can be prevented from being affected by the correction process of the projected image.
  • FIG. 4 is a flowchart of another method for correcting a projected image provided by an embodiment of the present disclosure.
  • the correction method can be applied to laser projection equipment. As shown in Figure 4, the method may include:
  • Step 401 in response to the correction instruction, display the target image on the projection screen.
  • the laser projection apparatus 10 can project and display the target image on the projection screen 20 in response to the correction instruction.
  • the target image may include a main picture and a plurality of characteristic graphics surrounding the main picture, and the color of each characteristic graphics is different from the background color of the area other than the main picture in the target image, thereby ensuring that the laser projection device is in the acquisition process.
  • the feature pattern can be identified from the captured image.
  • the characteristic pattern may be a quadrangle or a cross, or the like.
  • the target image 30 may include 12 characteristic graphics (eg, characteristic graphics 302a, 302b and 302c) surrounding the main screen 301, and the 12 characteristic graphics may all be cross-shaped.
  • the color of each feature graphic may be black, and the background color of the area other than the main screen 301 in the target image 30 may be white.
  • the laser projection device can keep the playing state of the main screen in the target image unchanged, thereby realizing the correction of the projection position of the projected image and ensuring the main The continuity of screen playback, thereby ensuring the continuity of user viewing.
  • the correction instruction may be triggered by a user through a projection client installed in the terminal.
  • a correction button may be displayed on the display interface of the projection client, and the projection client may generate a correction instruction after detecting the user's click operation on the correction button. Then the projection client can send the correction instruction to the laser projection device. After receiving the correction instruction sent by the projection client, the laser projection device can project and display the target image on the projection screen in response to the correction instruction.
  • the correction instruction may be triggered by a user through a remote control, and after receiving the correction instruction sent by the remote control, the laser projection device may, in response to the correction instruction, project and display the target image on the projection screen.
  • a calibration button may be provided on the laser projection device, and after detecting the user's click operation on the calibration button, the laser projection device may generate a calibration instruction, and then in response to the calibration instruction, the target image may be projected and displayed on the Projection screen.
  • the laser projection device may periodically generate a correction instruction, and in response to the correction instruction, may project and display the target image on the projection screen. That is, the laser projection apparatus can periodically perform the correction process of the target image.
  • Step 402 Acquire a photographed image obtained by photographing the projection screen by the camera.
  • the laser projection device 10 may be provided with a camera 40 , and the camera 40 may be connected to the laser projection device 10 by means of a universal serial bus (USB).
  • USB universal serial bus
  • the laser projection device 10 projects and displays the target image on the projection screen 20 , it can send a shooting instruction to the camera 40 .
  • the camera 40 can photograph the projection screen 20 to obtain a photographed image, and send the photographed image to the laser projection device 10, so that the laser projection device 10 can obtain the photographed image.
  • the camera can be independent of the laser projection device, and the user can control the camera to shoot the projection screen to obtain a captured image, and control the camera to send the captured image to the laser projection device, and then the laser projection device can obtain the captured image image.
  • Step 403 For each feature pattern, determine the first target projection position of the feature pattern on the projection screen according to the perspective transformation coefficient of the camera and the shooting position of the feature pattern in the shot image.
  • the projection screen may be polygonal.
  • the laser projection device can determine the shooting positions of multiple vertexes of the projection screen in the captured image, and can determine the shooting positions of the multiple vertexes of the projection screen according to the initial positions of the multiple vertexes of the projection screen and the multiple vertexes of the projection screen in the captured image.
  • the shooting position of the camera determines the perspective transformation coefficient of the camera.
  • the laser projection device can determine the first target projection position of the feature pattern on the projection screen according to the perspective transformation coefficient of the camera and the shooting position of the feature pattern in the shot image.
  • the perspective transformation coefficient can transform the position of any point on the projection screen into a position in the captured image, that is, the perspective transformation coefficient is a variation coefficient between the screen coordinate system of the projection screen and the image coordinate system of the captured image.
  • the perspective transformation coefficient is related to the shooting position of the camera, the distance between the camera and the projection screen, and the resolution of the camera.
  • the projection screen can be a quadrilateral, such as a rectangle.
  • the projection screen may include four vertices, a first vertex, a second vertex, a third vertex and a fourth vertex.
  • the first vertex may be the upper left vertex of the projection screen
  • the second vertex may be the upper right vertex of the projection screen
  • the third vertex may be the lower left vertex of the projection screen
  • the fourth vertex may be the projection screen the lower right vertex of .
  • the frame of the projection screen may include an inner frame and an outer frame, and the four vertices may be the vertices of the inner frame or the vertices of the outer frame, which are not limited in the embodiments of the present disclosure.
  • the position of each vertex is determined by two coordinates, the shooting position of the first vertex is (a1, b1), and the initial position of the first vertex is (x1, y1).
  • the shooting position of the second vertex is (a2, b2), and the initial position of the second vertex is (x2, y2).
  • the shooting position of the third vertex is (a3, b3), and the initial position of the third vertex is (x3, y3).
  • the shooting position of the fourth vertex is (a2, b2), and the initial position of the fourth vertex is (x4, y4).
  • the laser projection apparatus can determine a total of 8 equations from the following equations (1) to (8), and can determine the perspective transformation coefficients k0 to k7 by solving the 8 equations.
  • the laser projection device may determine a perspective transformation matrix according to the plurality of perspective transformation coefficients, and may determine an inverse matrix K -1 of the perspective transformation matrix. For each feature pattern, the laser projection device can determine the first target projection position of the feature pattern on the projection screen according to the inverse matrix K -1 of the perspective transformation matrix and the shooting position of the feature pattern.
  • the perspective transformation matrix K satisfies:
  • the inverse matrix K -1 of the perspective transformation matrix satisfies: the
  • the w satisfies: t ij is a parameter of the i-th row and the j-th column in the inverse matrix K -1 , and both i and j are positive integers less than or equal to 3.
  • the perspective transformation coefficient is related to the shooting position of the camera, the distance between the camera and the projection screen, and the resolution of the camera.
  • the laser projection device determines the perspective transformation coefficient of the camera based on the shot image, and determines the first target projection position of the feature pattern based on the perspective transformation coefficient and the shooting position of the feature pattern, thus improving the feature The accuracy of the determination of the first target projection position of the graphic.
  • the first target projection position of each feature graphic is the projection position of the feature graphic in the screen coordinate system of the projection screen, and the initial positions of the multiple vertices of the projection screen can be the multiple vertexes in the projection screen.
  • the shooting position of each feature graphic is the position of the feature graphic in the image coordinate system, and the shooting positions of the multiple vertices of the projection screen are the positions of the multiple vertexes in the image coordinate system.
  • the origin of the screen coordinate system is the center point of the projection screen, the horizontal axis of the screen coordinate system is parallel to the pixel row direction of the projection screen, and the vertical axis of the screen coordinate system is parallel to the pixel column direction of the projection screen.
  • the origin of the image coordinate system is the center point of the captured image, the horizontal axis of the image coordinate system is parallel to the pixel row direction of the captured image, and the vertical axis of the image coordinate system is parallel to the pixel column direction of the captured image.
  • the laser projection device when it determines the shooting positions of multiple feature patterns and multiple vertices of the projection screen, it can perform grayscale processing on the shot image to obtain a grayscale image. Afterwards, the laser projection device may determine the shooting position of each feature pattern of the projection screen and the shooting positions of multiple vertices of the projection screen in the captured image according to the grayscale value of each pixel in the grayscale image.
  • the gray value range of each pixel in the grayscale image may be [0, 255]. Wherein, a pixel with a grayscale value of 0 appears black in the grayscale image, and a pixel with a grayscale value of 255 appears white in the grayscale image.
  • each feature pattern may be composed of a plurality of target pixels included in one target pixel group. Since the distance between two adjacent feature patterns is within the first pixel range, the distance between two adjacent target pixel groups is within the first pixel range, and each target pixel group includes a plurality of target pixels The distance between any two adjacent target pixels is within the second pixel range.
  • the first pixel range and the second pixel range are fixed ranges pre-stored in the laser projection device.
  • the laser projection device can identify a plurality of pixels in the grayscale image whose grayscale values are less than the first grayscale value threshold, and can determine a plurality of target pixel groups from the plurality of pixels, and then can obtain that each target pixel group includes: The shooting positions of multiple target pixels. Afterwards, referring to FIG. 5 , the laser projection device may determine the shooting position of the vertex pixel of the feature graph formed by each target pixel group (for example, vertex pixel A shown in FIG. 5 ) in the captured image as the same as the target pixel group. The shooting position of the corresponding feature pattern.
  • the laser projection device may determine the shooting position of the feature pattern corresponding to the target pixel group from the shooting position of the center point pixel of the feature pattern formed by the target pixel group in the shot image. If the shape of each feature pattern is a polygon, the laser projection device can determine the shooting positions of multiple vertex pixels of the feature graphic enclosed by the target pixel group in the shot image, and can determine the shooting positions of the multiple vertex pixels. The average value is determined as the shooting position of the feature pattern corresponding to the target pixel group.
  • the first gray value threshold is a fixed range pre-stored in the laser projection device.
  • the embodiments of the present disclosure are described by taking as an example that the vertices of the projection screen are the vertices of the outer frame. If the color of the border of the projection screen is black, the laser projection device may determine the pixels in the grayscale image whose grayscale values are smaller than the second grayscale value threshold as edge pixels. Then the laser projection device can determine the position of the edge pixel in the grayscale image as the position of each pixel on the border of the projection screen in the captured image, and can determine the edge pixel that is farthest from the center point of the grayscale image. The positions of the four points are determined as the shooting positions of the four vertices.
  • the second gray value threshold may be a fixed value pre-stored in the laser projection device.
  • the grayscale values of the pixels between the inner and outer borders of the projection screen are within a fixed range.
  • the position in is the position of each pixel on the inner and outer borders of the projection screen in the captured image.
  • Step 404 Detect whether the first target projection positions of the plurality of feature patterns are all located within the projection screen.
  • the laser projection device can detect whether the first target projection positions of the plurality of feature patterns are located in the projection screen. If it is detected that the first target projection positions of the multiple feature patterns are all located in the projection screen, the laser projection device can determine that the deformation of the projection image is small, and after correcting the projection positions of the projection image, the image information loss of the projection image is relatively small. If less, the laser projection device may perform step 405 . If it is detected that the first target projection position of any feature pattern is outside the projection screen, the laser projection device can determine that the deformation of the projection image is relatively large, and after correcting the projection position of the projection image, the image information of the projection image is lost more. , so the laser projection device can perform step 408 .
  • the laser projection device can detect whether the distance between the first target projection position of the feature pattern and the initial position of the center point of the projection screen is smaller than the first pixel threshold. If it is detected that the value is smaller than the first pixel threshold, it can be determined that the first target projection position of the feature pattern is located within the projection screen. If it is detected that it is greater than or equal to the first pixel threshold, it can be determined that the first target projection position of the feature pattern is located outside the projection screen.
  • the first pixel threshold is a fixed value pre-stored in the laser projection device.
  • Step 405 Determine the second target projection position of the reference point on the projection screen according to the perspective transformation coefficient and the shooting position of the reference point in the main screen in the shot image.
  • the laser projection equipment After the laser projection equipment determines that the first target projection positions of the multiple feature patterns are all located within the projection screen, it can determine the reference point on the projection screen according to the perspective transformation coefficient and the shooting position of the reference point in the main screen in the captured image.
  • the w satisfies:
  • the reference point is located on the boundary of the main picture, for example, the reference point may be a vertex on the boundary of the main picture.
  • the color of the border of the main picture is different from the background color of the area other than the main picture in the target image, thereby ensuring that the reference point can be recognized by the laser projection device.
  • the laser projection device can determine a plurality of pixels in the grayscale image whose grayscale values are less than the third grayscale value threshold, And among the plurality of pixels, a pixel that is smaller than any one of the characteristic patterns is determined as a boundary pixel on the boundary of the main picture. Then, the laser projection device can determine the position of the boundary pixel in the grayscale image as the position of each pixel on the boundary of the main picture in the captured image.
  • the laser projection device can determine the positions of the four points farthest from the center point of the main picture in the boundary pixels as the four points on the boundary The shooting position of the vertex, from which the shooting position of the reference point can be determined.
  • the third gray value threshold may be a fixed value pre-stored in the laser projection device.
  • Step 406 Determine the third target projection position of the target vertex of the target image on the projection screen according to the first target projection position of the target feature graph, the second target projection position of the reference point, and the target ratio in the plurality of feature graphs.
  • the laser projection device After the laser projection device determines the first target projection position of the plurality of feature patterns and the second target projection position of the reference point, the laser projection device can determine the first target projection position of the target feature pattern in the plurality of feature patterns, the reference point The second target projection position and the target ratio determine the third target projection position of the target vertex of the target image on the projection screen.
  • the boundary of the target image, the boundary of the main screen, and the figure formed by the plurality of characteristic figures are all quadrilaterals.
  • the reference point may be a vertex of the boundary of the main picture.
  • the target feature graph is a feature graph whose distance from the reference point is less than the distance threshold.
  • the target ratio is positively correlated with the difference between the second initial projection position and the first initial projection position, and is negatively correlated with the difference between the third initial projection position and the first initial projection position.
  • the target vertex is the vertex closest to the reference point among the multiple vertices of the target image, the first initial projection position, the second initial projection position and the third initial projection position are the target vertex,
  • the distance threshold may be a fixed value pre-stored in the laser projection device.
  • the reference point 301 a may be the upper right vertex of the border of the main screen 301
  • the target vertex may be the vertex closest to the reference point 301 a among the vertices of the target image 30 , that is, in the target image 30 . top right vertex of .
  • the target feature pattern is a feature pattern whose distance from the reference point 301a is less than a distance threshold. That is, the target feature graph may be the feature graph 302a, or the feature graph 302b, or the feature graph 302c. Alternatively, the target feature graph may include feature graph 302a, feature graph 302b, and feature graph 302c.
  • the target ratio may include a first ratio and a second ratio
  • the laser projection device is based on the first target projection position of the target feature pattern in the plurality of feature patterns, the second target projection position of the reference point, and the target ratio.
  • the laser projection device can determine the third target projection of the target vertex according to the second coordinate g1 of the first target projection position of the target feature pattern, the second coordinate g2 of the second target projection position of the reference point, and the second ratio S2 The second coordinate g3 of the location.
  • the first coordinate of the third target projection position satisfies:
  • the first coordinate may be an abscissa
  • the second coordinate may be an ordinate.
  • the first ratio S1 may be the ratio of the first initial difference R to the second initial difference P, that is, the first ratio S1 satisfies:
  • the second ratio S2 may be the ratio of the third initial difference H to the fourth initial difference Q, that is, the second ratio S2 satisfies:
  • the first coordinate z1 of the first target projection position may be the average value of the first coordinates of the first target projection positions of the plurality of target feature patterns.
  • the second coordinate g1 of the first target projection position is the average value of the second coordinates of the second target projection positions of the plurality of target feature patterns.
  • Step 407 Correct the projection position of the projected image according to the third target projection position of the target vertex and the first initial projection position of the target vertex on the projection screen.
  • the laser projection device After determining the third target projection position of the target vertex, the laser projection device can correct the projection position of the projected image according to the third target projection position of the target vertex and the first initial projection position of the target vertex on the projection screen.
  • the laser projection device can determine the third target projection position when correcting the projection position of the projected image according to the third target projection position of the target vertex and the first initial projection position of the target vertex on the projection screen.
  • the pixels in the projected image can be controlled to move by the first target difference in a direction opposite to the first offset direction.
  • the laser projection device can It is determined that the first offset direction is a direction s1 parallel to the pixel row direction and away from the origin of the screen coordinate system.
  • the laser projection device can control the pixels in the projected image to be parallel to the pixel row direction and close to the origin of the screen coordinate system.
  • the direction s2 translates the first target difference. If the absolute value of the first coordinate of the third target projection position is smaller than the absolute value of the first coordinate of the first initial projection position, referring to FIG.
  • the laser projection device can determine that the first offset direction is parallel to the pixel row direction , and the direction s2 close to the origin of the screen coordinate system, the laser projection device can control the pixels in the projected image to translate the first target difference along the direction s1 parallel to the pixel row and away from the origin of the screen coordinate system.
  • the laser projection device may also determine a second target difference between the second coordinates of the third target projection position and the second coordinates of the first initial projection position, and the difference between the second coordinates of the third target projection position relative to the first initial projection position The second offset direction of the second coordinate. Further, the pixels in the projected image can be controlled to move by the second target difference in a direction opposite to the second offset direction.
  • the laser projection device can It is determined that the second offset direction is a direction s3 parallel to the pixel row direction and away from the origin of the screen coordinate system, then the laser projection device can control the pixels in the projected image to be parallel to the pixel row direction and close to the origin of the screen coordinate system The direction s4 translates the second target difference. If the absolute value of the second coordinate of the third target projection position is smaller than the absolute value of the second coordinate of the first initial projection position, referring to FIG.
  • the laser projection device can determine that the second offset direction is parallel to the pixel row direction , and the direction s4 is close to the origin of the screen coordinate system, the laser projection device can control the pixels in the projected image to translate the second target difference along the direction s3 parallel to the pixel column and away from the origin of the screen coordinate system.
  • Step 408 displaying prompt information.
  • the laser projection device After the laser projection device detects that the first target projection position of any feature pattern in the plurality of feature patterns is outside the projection screen, it can display prompt information, the prompt information is used to prompt that the deformation of the projected image is large, thereby reminding
  • the user adjusts the position of the laser projection device or the distortion coefficient of the projection lens in time to adjust the projection position of the projected image.
  • the prompt information may be "The projected image is greatly deformed, please adjust the position of the laser projection device".
  • the projection lens of the laser projection device is greatly distorted or the laser projection device is displaced, the projected image displayed on the projection screen will not be deformed, ensuring the projection The image display effect is better.
  • step 408 can be deleted according to the situation
  • steps 405 to 407 can be deleted according to the situation.
  • the embodiments of the present disclosure provide a method for calibrating a projected image, because the method can determine the feature pattern according to the perspective transformation coefficient, the shooting position of the feature pattern, and the shooting position of the reference point in the main screen
  • the projection position of the projected image may be corrected according to the first target projection position of the plurality of feature patterns and the second target projection position of the reference point. Therefore, even if the projection lens of the laser projection device is distorted or the laser projection device is displaced, the projected image displayed on the projection screen will not be deformed, thereby ensuring a better display effect of the projected image.
  • the method provided by the embodiment of the present disclosure can ensure the continuous playback of the main screen while correcting the projection position of the projected image. , so as to ensure the continuous viewing of the user, and the user experience is better.
  • the laser projection apparatus 10 may include a light source assembly 11 , a light modulation assembly 12 , a projection lens 13 , a position determination circuit 14 , a difference value determination circuit 15 and a correction circuit 16 .
  • the light source assembly 11 is used to emit a laser beam and transmit the laser beam to the light modulation assembly 12 .
  • the light source assembly 11 may include a laser light source and a light transmitting lens.
  • the laser light source is used for emitting a laser beam
  • the optical transmission lens is used for transmitting the laser beam emitted by the laser light source to the light modulation component 12 .
  • the laser light source may be a three-color laser light source, a single-color laser light source, or a two-color laser light source, which is not limited in this embodiment of the present disclosure.
  • the light modulation component 12 may be a digital micro-mirror device (DMD), a liquid crystal display (LCD) or a liquid crystal on silicon (LCOS) device.
  • DMD digital micro-mirror device
  • LCD liquid crystal display
  • LCOS liquid crystal on silicon
  • the correction circuit 16 is used to respond to the correction instruction, generate a control signal according to the pixel value of the target image, and control the light modulation component 12 according to the control signal to modulate the light beam irradiated on its surface into an image light beam, and transmit the image light beam to the projection Lens 13.
  • the projection lens 13 is used to transmit the image beam to the projection screen 20 to project and display the target image on the projection screen 20 .
  • the correction circuit 16 can send a shooting instruction to the camera 40 after detecting the target duration of the correction instruction. 20 captures and sends the resulting captured image to the position determination circuit 14 .
  • the position determination circuit 14 may then perform steps 102 to 104 and steps 402 to 406 described above.
  • the difference value determination circuit 15 is used to determine the first difference value, the first offset direction, the second difference value and the second offset direction, and send the position offset amount to the correction circuit 16 .
  • the correction circuit 16 is used for correcting the projection position of the projected image according to the first difference value, the first offset direction, the second difference value and the second offset direction.
  • an embodiment of the present disclosure provides a laser projection device, which is used for:
  • a target image is displayed on the projection screen, and the target image includes a main image and a plurality of feature patterns surrounding the main image, each feature pattern having a color different from the background color of an area other than the main image in the target image.
  • a captured image obtained by capturing the projection screen with a camera is acquired.
  • the first target projection position of the feature pattern on the projection screen is determined according to the perspective transformation coefficient of the camera and the shooting position of the feature pattern in the shot image.
  • the second target projection position of the reference point on the projection screen is determined according to the perspective transformation coefficient and the shooting position of the reference point in the main screen in the shot image.
  • the projection position of the projected image is corrected according to the first target projection position of the plurality of feature patterns and the second target projection position of the reference point.
  • the embodiments of the present disclosure provide a laser projection device, because the laser projection device can determine the characteristic pattern according to the perspective transformation coefficient, the shooting position of the characteristic pattern, and the shooting position of the reference point in the main screen.
  • the first target projection position and the second target projection position of the reference point The first target projection position and the second target projection position of the reference point.
  • the projection position of the projected image may be corrected according to the first target projection position of the plurality of feature patterns and the second target projection position of the reference point. Therefore, even if the projection lens of the laser projection device is distorted or the laser projection device is displaced, the projected image displayed on the projection screen will not be deformed, thereby ensuring a better display effect of the projected image.
  • the reference point is located on the boundary of the main picture, and the color of the boundary of the main picture is different from the background color of the area other than the main picture in the target image.
  • the laser projection device is used for:
  • the projection position of the projected image is corrected according to the third target projection position of the target vertex and the first initial projection position of the target vertex on the projection screen.
  • the target feature pattern is a feature pattern whose distance from the reference point is less than the distance threshold; the target ratio is positively correlated with the difference between the second initial projection position and the first initial projection position, and is directly related to the third initial projection position and the first initial projection.
  • the difference in position is negatively correlated.
  • the target vertex is the vertex closest to the reference point among the multiple vertices of the target image.
  • the first initial projection position, the second initial projection position and the third initial projection position are respectively the projection positions of the target vertex, target feature graph and reference point on the projection screen when the projection image is not deformed.
  • the target ratio may include a first ratio and a second ratio; the laser projection device is used for:
  • the first coordinates of the third target projection position of the target vertex are determined according to the first coordinates of the first target projection position of the target feature pattern, the first coordinates of the second target projection position of the reference point and the first ratio.
  • the second coordinate of the third target projected position of the target vertex is determined according to the second coordinate of the first target projected position of the target feature pattern, the second coordinate of the second target projected position of the reference point, and the second ratio.
  • the pixels in the projected image are controlled to move by the first target difference in a direction opposite to the first offset direction.
  • the pixels in the projected image are controlled to move by the second target difference in a direction opposite to the second offset direction.
  • the first ratio is the ratio of the first initial difference to the second initial difference
  • the first initial difference is the difference between the first coordinate of the second initial projection position and the first coordinate of the first initial projection position
  • the first The second initial difference is the difference between the first coordinates of the third initial projection position and the first coordinates of the first initial projection position
  • the second ratio is the ratio of the third initial difference to the fourth initial difference
  • the third initial difference is the difference between the second coordinate of the second initial projection position and the second coordinate of the first initial projection position
  • the fourth The initial difference is the difference between the second coordinates of the third initial projection position and the second coordinates of the first initial projection position.
  • the laser projection device is also used for:
  • the second target projection position of the reference point on the projection screen is determined according to the perspective transformation coefficient and the shooting position of the reference point in the main screen in the captured image .
  • the laser projection device is also used for:
  • prompt information is displayed, and the prompt information is used to prompt that the deformation of the projected image is large.
  • the embodiments of the present disclosure provide a laser projection device, because the laser projection device can determine the characteristic pattern according to the perspective transformation coefficient, the shooting position of the characteristic pattern, and the shooting position of the reference point in the main screen.
  • the first target projection position and the second target projection position of the reference point The first target projection position and the second target projection position of the reference point.
  • the projection position of the projected image may be corrected according to the first target projection position of the plurality of feature patterns and the second target projection position of the reference point. Therefore, even if the projection lens of the laser projection device is distorted or the laser projection device is displaced, the projected image displayed on the projection screen will not be deformed, thereby ensuring a better display effect of the projected image.
  • An embodiment of the present disclosure provides a laser projection device, including: a memory, a processor, and a computer program stored on the memory, and when the processor executes the computer program, the method for calibrating a projected image provided by the foregoing method embodiments is implemented, for example The method shown in Figure 1 or Figure 4.
  • Embodiments of the present disclosure provide a computer-readable storage medium, where instructions are stored in the computer-readable storage medium, and the instructions are loaded and executed by a processor to implement the method for calibrating a projected image provided by the foregoing method embodiments, for example, as shown in FIG. 1 or the method shown in Figure 4.
  • An embodiment of the present disclosure provides a computer program product containing instructions, when the computer program product runs on a computer, the computer is made to execute the projection image correction method provided by the above method embodiments, for example, as shown in FIG. 1 or FIG. 4 . Methods.
  • the terms “first”, “second”, “third” and “fourth” are used for descriptive purposes only, and should not be construed as indicating or implying relative importance.
  • the meaning of the term “plurality” in the embodiments of the present disclosure refers to two or more. The above are only optional embodiments of the present disclosure, and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection of the present disclosure. within the range.

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Abstract

本申请公开了一种投影图像的校正方法及激光投影设备。属于投影显示领域。由于该校正方法可以根据透视变换系数、特征图形的拍摄位置以及主画面中参考点的拍摄位置，确定出该特征图形的第一目标投影位置和该参考点的第二目标投影位置。并根据该多个特征图形的第一目标投影位置和参考点的第二目标投影位置，对投影图像的投影位置进行校正。由此即便在激光投影设备的投影镜头发生畸变或者该激光投影设备发生位移的情况下，该投影显示在投影屏幕上的投影图像也不会发生形变，从而确保投影图像的显示效果较好。并且，由于在对投影图像进行校正的过程中，投影屏幕中显示的目标图像中包括主画面，因此能够确保主画面的连续播放。

Description

投影图像的校正方法及激光投影设备
相关申请的交叉引用
本申请要求在2021年3月31日提交中国专利局、申请号为202110348649.2，发明名称为投影图像的校正方法及激光投影设备的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本公开涉及投影显示领域，特别涉及一种投影图像的校正方法及激光投影设备。
背景技术
目前，激光投影设备可以将投影图像投影显示至投影屏幕上。但是，若激光投影设备的投影镜头发生畸变，则该激光投影设备投影显示至投影屏幕上的投影图像会发生形变，导致显示的投影图像的显示效果较差。
发明内容
本公开实施例一方面，提供了一种投影图像的校正方法，应用于激光投影设备，所述方法包括：
响应于校正指令，在投影屏幕显示目标图像，所述目标图像包括主画面以及环绕所述主画面的多个特征图形，每个所述特征图形的颜色与所述目标图像中除所述主画面之外的区域的背景色不同；
获取摄像机对所述投影屏幕进行拍摄得到的拍摄图像；
对于每个所述特征图形，根据所述摄像机的透视变换系数和所述特征图形在所述拍摄图像中的拍摄位置，确定所述特征图形在所述投影屏幕上的第一目标投影位置；
根据所述透视变换系数和所述主画面中的参考点在所述拍摄图像中的拍摄位置，确定所述参考点在所述投影屏幕上的第二目标投影位置；
根据所述多个特征图形的第一目标投影位置和所述参考点的第二目标投影位置，对投影图像的投影位置进行校正。
另一方面，提供了一种激光投影设备，所述激光投影设备，用于：
响应于校正指令，在投影屏幕显示目标图像，所述目标图像包括主画面以及环绕所述主画面的多个特征图形，每个所述特征图形的颜色与所述目标图像中除所述主画面之外的区域的背景色不同；
获取摄像机对所述投影屏幕进行拍摄得到的拍摄图像；
对于每个所述特征图形，根据所述摄像机的透视变换系数和所述特征图形在所述拍摄图像中的拍摄位置，确定所述特征图形在所述投影屏幕上的第一目标投影位置；
根据所述透视变换系数和所述主画面中的参考点在所述拍摄图像中的拍摄位置，确定所述参考点在所述投影屏幕上的第二目标投影位置；
根据所述多个特征图形的第一目标投影位置和所述参考点的第二目标投影位置，对投影图像的投影位置进行校正。
附图说明
为了更清楚地说明本公开实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本公开的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本公开实施例提供的一种投影图像的校正方法的流程图；
图2是本公开实施例提供的一种激光投影设备的结构示意图；
图3是本公开实施例提供的一种目标图像的结构示意图；
图4是本公开实施例提供的一种投影图像的校正方法的流程图；
图5是本公开实施例提供的一种特征图形的示意图；
图6是相关技术提供的一种投影图像发生形变的示意图；
图7是相关技术提供的另一种投影图像发生形变的示意图；
图8是相关技术提供的再一种投影图像发生形变的示意图；
图9是本公开实施例提供的另一种激光投影设备的结构示意图。
具体实施方式
为使本公开的目的、技术方案和优点更加清楚，下面将结合附图对本公开实施方式作进一步地详细描述。
图1是本公开实施例提供的一种投影图像的校正方法的流程图。该校正方法可以应用于激光投影设备。如图1所示，该方法可以包括：
步骤101、响应于校正指令，在投影屏幕显示目标图像。
参考图2，该激光投影设备10可以响应于校正指令，在投影屏幕20上投影显示目标图像。其中，参考图3，该目标图像30可以包括主画面301以及环绕该主画面301的多个特征图形(例如，特征图形302a、特征图形302b和特征图形302c)。该每个特征图形的颜 色与该目标图像30中除主画面301之外的区域的背景色不同。示例的，参考图3，该每个特征图形的颜色可以为黑色，该目标图像30中除主画面301之外的区域的背景色可以为白色。
激光投影设备在投影显示目标图像的过程中，可以保持目标图像中主画面的播放状态不变，由此实现在对投影图像的投影位置进行校正的同时，确保主画面播放的连续性，进而确保用户观看的连续性。
步骤102、获取摄像机对投影屏幕进行拍摄得到的拍摄图像。
参考图2，该激光投影设备10上可以设置有摄像机40。该激光投影设备在将目标图像投影显示至投影屏幕后，可以向该摄像机发送拍摄指令。该摄像机在接收到该拍摄指令之后，可以对投影屏幕20进行拍摄得到拍摄图像，并将该拍摄图像发送至激光投影设备10，进而激光投影设备10可以获取到拍摄图像。
或者，该摄像机可以独立于该激光投影设备，用户可以控制该摄像机对该投影屏幕进行拍摄得到拍摄图像，并控制该摄像机将该拍摄图像发送至激光投影设备，进而激光投影设备可以获取到拍摄图像。
步骤103、对于每个特征图形，根据摄像机的透视变换系数和特征图形在拍摄图像中的拍摄位置，确定特征图形在投影屏幕上的第一目标投影位置。
激光投影设备在获取到拍摄图像之后，对于每个特征图形，激光投影设备可以根据该摄像机的透视变换系数和该特征图形在该拍摄图像中的拍摄位置，确定该特征图形在投影屏幕上的第一目标投影位置。
该透视变换系数能够将投影屏幕中任一点的位置变换为在拍摄图像中的位置，即该透视变换系数为投影屏幕的坐标系与拍摄图像的坐标系之间的变化系数。该透视变换系数与该摄像机的拍摄位置、该摄像机与投影屏幕的距离以及该摄像机的分辨率相关。在一具体实施中，该投影屏幕可以为多边形，例如可以为矩形。
步骤104、根据透视变换系数和主画面中的参考点在拍摄图像中的拍摄位置，确定参考点在投影屏幕上的第二目标投影位置。
激光投影设备在获取到拍摄图像之后，还可以根据该摄像机的透视变换系数和主画面中的参考点在该拍摄图像中的拍摄位置，确定该参考点在投影屏幕上的第二目标投影位置。其中，该参考点可以位于该主画面的边界上，或者，该参考点可以为该主画面的中心点。
步骤105、根据多个特征图形的第一目标投影位置和参考点的第二目标投影位置，对投影图像的投影位置进行校正。
激光投影设备在确定多个特征图形的第一目标投影位置和参考点的第二目标投影位 置之后，可以根据该多个特征图形的第一目标投影位置和参考点的第二目标投影位置，对投影图像的投影位置进行校正。
在一具体实施中，激光投影设备可以根据该多个特征图形中目标特征图形的第一目标投影位置，以及该参考点的第二目标投影位置，确定该目标图像的目标顶点在该投影屏幕上的第三目标投影位置。进而，可以根据该目标顶点的第三目标投影位置和该目标顶点在该投影屏幕上的第一初始投影位置，对投影图像的投影位置进行校正。例如，可以基于该第三目标投影位置与该第一初始投影位置的差值来调整投影图像的投影位置，以实现对投影位置的校正。其中，该目标顶点的第一初始投影位置可以为该在投影图像未发生形变时，该目标顶点在该投影屏幕上的位置。
综上所述，本公开实施例提供了一种投影图像的校正方法，由于该校正方法可以根据透视变换系数、特征图形的拍摄位置以及主画面中参考点的拍摄位置，确定出该特征图形的第一目标投影位置和该参考点的第二目标投影位置。之后，可以根据该多个特征图形的第一目标投影位置和参考点的第二目标投影位置，对投影图像的投影位置进行校正。由此即便在激光投影设备的投影镜头发生畸变或者该激光投影设备发生位移的情况下，该投影显示在投影屏幕上的投影图像也不会发生形变，从而确保投影图像的显示效果较好。
并且，由于在对投影图像进行校正的过程中，投影屏幕中显示的目标图像中包括主画面，因此能够确保主画面的连续播放，避免投影图像的校正流程影响主画面播放的连续性。
图4是本公开实施例提供的另一种投影图像的校正方法的流程图。该校正方法可以应用于激光投影设备。如图4所示，该方法可以包括：
步骤401、响应于校正指令，在投影屏幕显示目标图像。
参考图2，该激光投影设备10可以响应于校正指令，在投影屏幕20上投影显示目标图像。该目标图像可以包括主画面以及环绕该主画面的多个特征图形，该每个特征图形的颜色与该目标图像中除主画面之外的区域的背景色不同，由此确保激光投影设备在获取到拍摄图像后，可以从该拍摄图像中识别出该特征图形。在一具体实施中，该特征图形可以为四边形或者十字形等。
示例的，参考图3，该目标图像30可以包括环绕在主画面301的12个特征图形(例如，特征图形302a、特征图形302b和特征图形302c)，该12个特征图形可以均为十字形。该每个特征图形的颜色可以为黑色，该目标图像30中除主画面301之外的区域的背景色可以为白色。
在本公开实施例中，激光投影设备在显示目标图像的过程中，可以保持该目标图像中 的主画面的播放状态不变，由此实现在对投影图像的投影位置进行校正的同时，确保主画面播放的连续性，进而确保用户观看的连续性。
在一具体实施中，该校正指令可以是用户通过终端中安装的投影客户端触发的。该投影客户端的显示界面可以显示有校正按钮，该投影客户端在检测到用户针对该校正按钮的点击操作后，可以生成校正指令。之后投影客户端可以将该校正指令发送至激光投影设备。该激光投影设备在接收到投影客户端发送的校正指令后，可以响应于该校正指令，将该目标图像投影显示至投影屏幕。
或者，该校正指令可以是用户通过遥控器触发的，该激光投影设备在接收到遥控器发送的校正指令后，可以响应于该校正指令，将目标图像投影显示至投影屏幕。
或者，该激光投影设备上可以设置有校正按钮，该激光投影设备在检测到用户针对该校正按钮的点击操作后，可以生成校正指令，进而可以响应于该校正指令，将该目标图像投影显示至投影屏幕。
或者，该激光投影设备可以周期性生成校正指令，并可以响应于该校正指令，将该目标图像投影显示至投影屏幕。也即是，该激光投影设备可以周期性执行该目标图像的校正流程。
步骤402、获取摄像机对投影屏幕进行拍摄得到的拍摄图像。
参考图2，该激光投影设备10上可以设置有摄像机40，该摄像机40可以通过通用串行总线(universal serial bus，USB)的方式与该激光投影设备10连接。激光投影设备10在将目标图像投影显示至投影屏幕20后，可以向该摄像机40发送拍摄指令。该摄像机40在接收到该拍摄指令之后，可以对投影屏幕20进行拍摄得到拍摄图像，并将该拍摄图像发送至激光投影设备10，进而激光投影设备10可以获取到该拍摄图像。
或者，该摄像机可以独立于该激光投影设备，用户可以控制该摄像机对该投影屏幕进行拍摄得到拍摄图像，并控制该摄像机将该拍摄图像发送至激光投影设备，进而激光投影设备可以获取到该拍摄图像。
步骤403、对于每个特征图形，根据摄像机的透视变换系数和特征图形在拍摄图像中的拍摄位置，确定特征图形在投影屏幕上的第一目标投影位置。
在本公开实施例中，该投影屏幕可以为多边形。激光投影设备在获取到拍摄图像之后，可以确定该拍摄图像中投影屏幕的多个顶点的拍摄位置，并可以根据该投影屏幕的多个顶点的初始位置，以及拍摄图像中投影屏幕的多个顶点的拍摄位置，确定该摄像机的透视变换系数。之后，对于每个特征图形，激光投影设备可以根据该摄像机的透视变换系数和该特征图形在该拍摄图像中的拍摄位置，确定该特征图形在投影屏幕上的第一目标投影位置。
其中，该透视变换系数能够将投影屏幕中任一点的位置变换为在拍摄图像中的位置，即该透视变换系数为投影屏幕的屏幕坐标系与拍摄图像的图像坐标系之间的变化系数。该透视变换系数与该摄像机的拍摄位置、该摄像机与投影屏幕的距离以及该摄像机的分辨率相关。
在一具体实施中，该投影屏幕可以为四边形，例如可以为矩形。相应的，该投影屏幕可以包括第一顶点、第二顶点、第三顶点和第四顶点共四个顶点。其中，该第一顶点可以为该投影屏幕的左上顶点，该第二顶点可以为该投影屏幕的右上顶点，该第三顶点可以为该投影屏幕的左下顶点，该第四顶点可以为该投影屏幕的右下顶点。
在一具体实施中，投影屏幕的边框可以包括内边框和外边框，该四个顶点可以为该内边框的顶点，也可以为该外边框的顶点，本公开实施例对此不做限定。
其中，每个顶点的位置由两个坐标确定，该第一顶点的拍摄位置为(a1，b1)，该第一顶点的初始位置为(x1，y1)。该第二顶点的拍摄位置为(a2，b2)，该第二顶点的初始位置为(x2，y2)。该第三顶点的拍摄位置为(a3，b3)，第三顶点的初始位置为(x3，y3)。该第四顶点的拍摄位置为(a2，b2)，第四顶点的初始位置为(x4，y4)。上述四个顶点的初始位置、四个顶点的拍摄位置以及透视变换系数k0至k7可以满足：
Figure PCTCN2022082627-appb-000001
基于上述公式，激光投影设备可以确定以下方程(1)至方程(8)共8个方程，并可以通过求解该8个方程确定出透视变换系数k0至k7。
方程(1)：a1＝k0×x1+k1×y1+k2-k6×x1×a1-k7×y1×a1；
方程(2)：b1＝k3×x1+k4×y1+k5-k6×x1×b1-k7×y1×b1；
方程(3)：a2＝k0×x2+k1×y2+k2-k6×x2×a2-k7×y2×a2；
方程(4)：b2＝k3×x2+k4×y2+k5-k6×x2×b2-k7×y2×b2；
方程(5)：a3＝k0×x3+k1×y3+k2-k6×x3×a3-k7×y3×a3；
方程(6)：b3＝k3×x3+k4×y3+k5-k6×x3×b3-k7×y3×b3；
方程(7)：a4＝k0×x4+k1×y4+k2-k6×x4×a4-k7×y4×a4；
方程(8)：b4＝k3×x4+k4×y4+k5-k6×x4×b4-k7×y4×b4。
激光投影设备在确定多个透视变换系数之后，可以根据该多个透视变换系数确定透视变换矩阵，并可以确定该透视变换矩阵的逆矩阵K -1。对于每个特征图形，激光投影设备可以根据该透视变换矩阵的逆矩阵K -1和该特征图形的拍摄位置，确定该特征图形在投影屏幕上的第一目标投影位置。
其中，该透视变换矩阵K和透视变换矩阵的逆矩阵K -1均可以为3×3的矩阵，该K×K -1＝E，该E为3×3的单位矩阵。该透视变换矩阵K满足：
Figure PCTCN2022082627-appb-000002
透视变换矩阵的逆矩阵K -1满足：该
Figure PCTCN2022082627-appb-000003
该拍摄图像中拍摄位置为(a，b)的特征图形在投影屏幕上的第一目标投影位置(X1，Y1)满足：X1＝t 11×w×a+t 12×w×b+t 13×w；Y1＝t 21×w×a+t 22×w×b+t 23×w。该w满足：
Figure PCTCN2022082627-appb-000004
t ij为逆矩阵K -1中第i行第j列的参数，i和j均为小于等于3的正整数。
在本公开实施例中，由于透视变换系数与摄像机的拍摄位置、摄像机与投影屏幕的距离以及摄像机的分辨率相关。对于每张拍摄图像，激光投影设备均基于该拍摄图像确定摄像机的透视变换系数，并基于该透视变换系数和特征图形的拍摄位置确定该特征图形的第一目标投影位置，因此提高了对该特征图形的第一目标投影位置确定的准确性。
在一具体实施中，该每个特征图形的第一目标投影位置是该特征图形在投影屏幕的屏幕坐标系中的投影位置，该投影屏幕的多个顶点的初始位置可以为该多个顶点在该屏幕坐标系中的位置。该每个特征图形的拍摄位置为该特征图形在图像坐标系中的位置，该投影屏幕的多个顶点的拍摄位置为该多个顶点在图像坐标系中的位置。
其中，该屏幕坐标系的原点为投影屏幕的中心点，该屏幕坐标系的横轴平行于该投影屏幕的像素行方向，该屏幕坐标系的纵轴平行于该投影屏幕的像素列方向。该图像坐标系的原点为拍摄图像的中心点，该图像坐标系的横轴平行与该拍摄图像的像素行方向，该图像坐标系的纵轴平行与该拍摄图像的像素列方向。
在本公开实施例中，激光投影设备在确定多个特征图形和投影屏幕的多个顶点的拍摄位置时，可以对该拍摄图像进行灰度处理，得到灰度图像。之后，激光投影设备可以根据该灰度图像中每个像素的灰度值，确定该拍摄图像中的投影屏幕的每个特征图形的拍摄位置和投影屏幕的多个顶点的拍摄位置。
其中，该灰度图像中每个像素的灰度值范围可以为[0，255]。其中，像素的灰度值为0的像素在该灰度图像中呈现出来是黑色，像素的灰度值为255的像素在该灰度图像中呈现 出来是白色。
在本公开实施例中，每个特征图形可以由一个目标像素组所包括的多个目标像素组成。由于相邻两个特征图形之间的间距位于第一像素范围内，因此相邻两个目标像素组之间的间距位于该第一像素范围内，且每个目标像素组包括的多个目标像素中任意相邻两个目标像素的间距位于第二像素范围内。其中，该第一像素范围和第二像素范围均为激光投影设备中预先存储的固定范围。
激光投影设备可以识别灰度图像中灰度值小于第一灰度值阈值的多个像素，并可以从该多个像素中确定出多个目标像素组，进而可以得到该每个目标像素组包括的多个目标像素的拍摄位置。之后，参考图5，激光投影设备可以将该每个目标像素组形成的特征图形的顶点像素(例如图5所示的顶点像素A)在拍摄图像中的拍摄位置，确定为与该目标像素组对应的特征图形的拍摄位置。或者，激光投影设备可以将该目标像素组形成的特征图形的中心点像素在拍摄图像中的拍摄位置，确定与该目标像素组对应的特征图形的拍摄位置。若每个特征图形的形状为多边形，则激光投影设备可以确定该目标像素组围成的特征图形的多个顶点像素在拍摄图像中的拍摄位置，并可以将该多个顶点像素的拍摄位置的平均值确定为与该目标像素组对应的特征图形的拍摄位置。其中，该第一灰度值阈值为激光投影设备中预先存储的固定范围。
本公开实施例以投影屏幕的多个顶点为外边框的顶点为例进行说明。若投影屏幕的边框的颜色为黑色，则激光投影设备可以将该灰度图像中灰度值小于第二灰度值阈值的像素确定为边缘像素。之后激光投影设备可以将该边缘像素在灰度图像中的位置确定为拍摄图像中的投影屏幕的边框上每个像素的位置，并可以将该边缘像素中距离灰度图像的中心点最远的四个点的位置确定为该四个顶点的拍摄位置。其中，该第二灰度值阈值可以为激光投影设备中预先存储的固定数值。
由于投影屏幕的内边框和外边框的颜色相近，因此投影屏幕的内边框和外边框之间的像素的灰度值处于一个固定的范围内，采用该方法确定出多个边缘像素在灰度图像中的位置为该拍摄图像中的投影屏幕的内边框和外边框上每个像素的位置。
步骤404、检测多个特征图形的第一目标投影位置是否均位于投影屏幕内。
激光投影设备在确定每个特征图形的第一目标投影位置之后，可以检测该多个特征图形的第一目标投影位置是否位于投影屏幕内。若检测到该多个特征图形的第一目标投影位置均位于投影屏幕内，则激光投影设备可以确定投影图像的形变较小，在校正投影图像的投影位置之后，该投影图像的图像信息损失较少，则激光投影设备可以执行步骤405。若检测到任一特征图形的第一目标投影位置位于投影屏幕之外，激光投影设备可以确定投影 图像的形变较大，在校正该投影图像的投影位置之后，该投影图像的图像信息损失较多，因此激光投影设备可以执行步骤408。
对于每个特征图形，激光投影设备可以检测该特征图形的第一目标投影位置与投影屏幕的中心点的初始位置之间的间距是否小于第一像素阈值。若检测到小于第一像素阈值，则可以确定该特征图形的第一目标投影位置位于投影屏幕之内。若检测到大于或等于第一像素阈值，则可以确定该特征图形的第一目标投影位置位于投影屏幕之外。其中，该第一像素阈值为激光投影设备中预先存储的固定数值。
步骤405、根据透视变换系数和主画面中的参考点在拍摄图像中的拍摄位置，确定参考点在投影屏幕上的第二目标投影位置。
激光投影设备在确定多个特征图形的第一目标投影位置均位于投影屏幕之内后，可以根据透视变换系数和主画面中的参考点在拍摄图像中的拍摄位置，确定参考点在投影屏幕上的第二目标投影位置。
在本公开实施例中，该拍摄图像中拍摄位置为(c，d)的参考点在投影屏幕上的第二目标投影位置(X2，Y2)满足：X2＝t 11×w×c+t 12×w×d+t 13×w；Y2＝t 21×w×c+t 22×w×d+t 23×w。该w满足：
Figure PCTCN2022082627-appb-000005
在一具体实施中，该参考点位于主画面的边界上，例如，该参考点可以为该主画面的边界上的顶点。该主画面的边界的颜色与目标图像中除主画面之外的区域的背景色不同，由此确保激光投影设备可以识别到该参考点。
由于该主画面的边界的颜色与目标图像中除主画面之外的区域的背景色不同，因此激光投影设备可以确定该灰度图像中灰度值小于第三灰度值阈值的多个像素，并将该多个像素中位于小于任一特征图形的像素确定为主画面的边界上的边界像素。之后激光投影设备可以将该边界像素在灰度图像中的位置确定为拍摄图像中的主画面的边界上每个像素的位置。若该主画面的边界为四边形，该参考点为该边界上的顶点，则激光投影设备可以将该边界像素中距离主画面的中心点最远的四个点的位置确定为边界上的四个顶点的拍摄位置，由此可以确定出参考点的拍摄位置。其中，该第三灰度值阈值可以为激光投影设备中预先存储的固定数值。
步骤406、根据多个特征图形中目标特征图形的第一目标投影位置、参考点的第二目标投影位置以及目标比值，确定目标图像的目标顶点在投影屏幕上的第三目标投影位置。
激光投影设备在确定多个特征图形的第一目标投影位置以及参考点的第二目标投影位置之后，激光投影设备可以根据该多个特征图形中目标特征图形的第一目标投影位置、参考点的第二目标投影位置以及目标比值，确定目标图像的目标顶点在投影屏幕上的第三 目标投影位置。
其中，该目标图像的边界，该主画面的边界，以及该多个特征图形组成的图形均为四边形。该参考点可以为主画面的边界的顶点。该目标特征图形为与参考点的距离小于距离阈值的特征图形。该目标比值与第二初始投影位置和第一初始投影位置的差值正相关，且与第三初始投影位置和第一初始投影位置的差值负相关。该目标顶点为该目标图像的多个顶点中距离参考点最近的顶点，该第一初始投影位置，第二初始投影位置和第三初始投影位置分别为投影图像未发生形变时，该目标顶点、该目标特征图形和参考点在投影屏幕上的投影位置。该距离阈值可以为激光投影设备中预先存储的固定数值。
示例的，参考图2，该参考点301a可以为主画面301的边界的右上顶点，该目标顶点可以为该目标图像30的多个顶点中距离参考点301a最近的顶点，即该目标图像30中的右上顶点。该目标特征图形为与参考点301a的距离小于距离阈值的特征图形。即该目标特征图形可以为特征图形302a，或者特征图形302b或者特征图形302c。或者，该目标特征图形可以包括特征图形302a、特征图形302b和特征图形302c。
在一具体实施中，该目标比值可以包括第一比值和第二比值，激光投影设备在根据多个特征图形中目标特征图形的第一目标投影位置、参考点的第二目标投影位置以及目标比值，确定目标图像的目标顶点在投影屏幕上的第三目标投影位置时，可以根据目标特征图形的第一目标投影位置的第一坐标z1、参考点的第二目标投影位置的第一坐标z2以及第一比值S1，确定目标顶点的第三目标投影位置的第一坐标z3。其中，该第三目标投影位置的第一坐标满足：
Figure PCTCN2022082627-appb-000006
并且，激光投影设备可以根据该目标特征图形的第一目标投影位置的第二坐标g1、参考点的第二目标投影位置的第二坐标g2以及第二比值S2，确定目标顶点的第三目标投影位置的第二坐标g3。其中，该第三目标投影位置的第一坐标满足：
Figure PCTCN2022082627-appb-000007
在一具体实施中，该第一坐标可以为横坐标，该第二坐标可以为纵坐标。
其中，该第一比值和第二比值均为激光投影设备中预先存储的固定数值。该第一比值S1可以为第一初始差值R与第二初始差值P的比值，即第一比值S1满足：
Figure PCTCN2022082627-appb-000008
该第一初始差值R为第二初始投影位置的第一坐标r1和第一初始投影位置的第一坐标r2的差值，即第一初始差值R满足：R＝r1-r2。该第二初始差值P为第三初始投影位置的第一坐标p和第一初始投影位置的第一坐标r2的差值，即该第二初始差值P满足：P＝p-r2。
该第二比值S2可以为第三初始差值H与第四初始差值Q的比值，即该第二比值S2满足：
Figure PCTCN2022082627-appb-000009
该第三初始差值H为第二初始投影位置的第二坐标h1和第一初始投影位置的第二坐标h2的差值，即该第三初始差值H满足：H＝h1-h2。第四初始差值Q为第三初始投影位置的第二坐标q和第一初始投影位置的第二坐标h2的差值，即第四初始差值Q满足：该Q＝q-h2。
在一具体实施中，若该目标特征图形的个数大于1，则该第一目标投影位置的第一坐标z1可以为该多个目标特征图形的第一目标投影位置的第一坐标的平均值，该第一目标投 影位置的第二坐标g1为该多个目标特征图形的第二目标投影位置的第二坐标的平均值。
步骤407、根据目标顶点的第三目标投影位置和目标顶点在投影屏幕上的第一初始投影位置，对投影图像的投影位置进行校正。
激光投影设备在确定目标顶点的第三目标投影位置之后，可以根据该目标顶点的第三目标投影位置和该目标顶点在投影屏幕上的第一初始投影位置，对投影图像的投影位置进行校正。
在一具体实施中，激光投影设备在根据目标顶点的第三目标投影位置和目标顶点在投影屏幕上的第一初始投影位置，对投影图像的投影位置进行校正时，可以确定第三目标投影位置的第一坐标和第一初始投影位置的第一坐标的第一目标差值，以及第三目标投影位置的第一坐标相对于第一初始投影位置的第一坐标的第一偏移方向。进而可以控制投影图像中的像素沿与第一偏移方向相反的方向移动第一目标差值。
假设目标图像的目标顶点为该目标图像的右上顶点，该第三目标投影位置的第一坐标的绝对值大于第一初始投影位置的第一坐标的绝对值，则参考图2，激光投影设备可以确定该第一偏移方向为平行于像素行方向，且远离屏幕坐标系的原点的方向s1，激光投影设备可以控制投影图像中的像素沿平行于像素行方向，且靠近屏幕坐标系的原点的方向s2平移第一目标差值。若该第三目标投影位置的第一坐标的绝对值小于第一初始投影位置的第一坐标的绝对值，则参考图2，激光投影设备可以确定该第一偏移方向为平行于像素行方向，且靠近屏幕坐标系的原点的方向s2，则激光投影设备可以控制投影图像中的像素沿平行于像素行方向，且远离屏幕坐标系的原点的方向s1平移第一目标差值。
激光投影设备还可以确定第三目标投影位置的第二坐标和第一初始投影位置的第二坐标的第二目标差值，以及第三目标投影位置的第二坐标相对于第一初始投影位置的第二坐标的第二偏移方向。进而可以控制投影图像中的像素沿与第二偏移方向相反的方向移动第二目标差值。
假设目标图像的目标顶点为该目标图像的右上顶点，该第三目标投影位置的第二坐标的绝对值大于第一初始投影位置的第二坐标的绝对值，则参考图2，激光投影设备可以确定该第二偏移方向为平行于像素列方向，且远离屏幕坐标系的原点的方向s3，则激光投影设备可以控制投影图像中的像素沿平行于像素列方向，且靠近屏幕坐标系的原点的方向s4平移第二目标差值。若该第三目标投影位置的第二坐标的绝对值小于第一初始投影位置的第二坐标的绝对值，则参考图2，激光投影设备可以确定该第二偏移方向为平行于像素列方向，且靠近屏幕坐标系的原点的方向s4，则激光投影设备可以控制投影图像中的像素沿平行于像素列方向，且远离屏幕坐标系的原点的方向s3平移第二目标差值。
步骤408、显示提示信息。
激光投影设备在检测到该多个特征图形中任一特征图形的第一目标投影位置位于投影屏幕之外后，可以显示提示信息，该提示信息用于提示投影图像的形变较大，由此提醒用户及时调整激光投影设备的位置或者投影镜头的畸变系数，以调整投影图像的投影位置。示例的，该提示信息可以为“投影图像形变较大，请调整激光投影设备的位置”。
相关技术中，参考图6和图7，在激光投影设备发生位移之后，投影屏幕20和投影图像50之间存在夹角，此时，该投影图像50会发生梯形形变。参考图8，在激光投影设备的投影镜头发生较大畸变后，该投影图像50的边缘会存在形变。
采用本公开实施例提供的方法，即便在激光投影设备的投影镜头发生较大畸变或者该激光投影设备发生位移的情况下，该投影显示在投影屏幕上的投影图像也不会发生形变，确保投影图像的显示效果较好。
需要说明的是，本公开实施例提供的投影图像的校正方法步骤的先后顺序可以进行适当调整，步骤也可以根据情况进行删除。例如，步骤408可以根据情况进行删除，或者步骤405至步骤407可以根据情况进行删除。任何熟悉本技术领域的技术人员在本公开揭露的技术范围内，可轻易想到变化的方法，都应涵盖在本公开的保护范围之内，因此不再赘述。
综上所述，本公开实施例提供了一种投影图像的校正方法，由于该校正方法可以根据透视变换系数、特征图形的拍摄位置以及主画面中的参考点的拍摄位置，确定出该特征图形的第一目标投影位置和该参考点的第二目标投影位置。之后，可以根据该多个特征图形的第一目标投影位置和参考点的第二目标投影位置对投影图像的投影位置进行校正。由此即便在激光投影设备的投影镜头发生畸变或者该激光投影设备发生位移的情况下，该投影显示在投影屏幕上的投影图像也不会发生形变，从而确保投影图像的显示效果较好。
并且，由于显示的目标图像中包括主画面，且该主画面的播放状态保持不变，因此采用本公开实施例提供的方法能够在对投影图像的投影位置校正的同时，确保主画面的连续播放，进而确保用户的连续观看，用户体验较好。
参考图9，该激光投影设备10可以包括光源组件11、光调制组件12、投影镜头13、位置确定电路14、差值确定电路15和校正电路16。
其中，该光源组件11用于出射激光光束，并将该激光光束传输至光调制组件12。该光源组件11可以包括激光光源和光传输镜片。该激光光源用于出射激光光束，该光传输镜片用于将该激光光源出射的激光光束传输至光调制组件12。该激光光源可以为三色激光光 源，也可以为单色激光光源，或者也可以为双色激光光源，本公开实施例对此不做限定。该光调制组件12可以为数字微镜器件(digital micro-mirror device，DMD)、液晶显示器(liquid crystal display，LCD)或硅基液晶(liquid crystal on silicon，LCOS)器件。
该校正电路16用于响应于校正指令，根据目标图像的像素值生成控制信号，并根据控制信号控制光调制组件12将照射至其表面的光束调制成影像光束，并将该影像光束传输至投影镜头13。该投影镜头13用于将影像光束传输至投影屏幕20，以在投影屏幕20上投影显示目标图像。
若该摄像机40与校正电路16和位置确定电路14连接，则校正电路16可以在检测到校正指令的目标时长后，向摄像机40发送拍摄指令，该摄像机40在接收到该拍摄指令之后对投影屏幕20进行拍摄，并将得到的拍摄图像发送至位置确定电路14。该位置确定电路14进而可以执行上述步骤102至步骤104，以及步骤402至步骤406。
之后，差值确定电路15和校正电路16执行上述步骤104和上述步骤407。差值确定电路15用于确定第一差值、第一偏移方向、第二差值和第二偏移方向，并将该位置偏移量发送至校正电路16。该校正电路16用于根据该第一差值、第一偏移方向、第二差值和第二偏移方向对投影图像的投影位置进行校正。
参考图2和图9，本公开实施例提供了一种激光投影设备，该激光投影设备用于：
响应于校正指令，在投影屏幕显示目标图像，目标图像包括主画面以及环绕主画面的多个特征图形，每个特征图形的颜色与目标图像中除主画面之外的区域的背景色不同。
获取摄像机对投影屏幕进行拍摄得到的拍摄图像。
对于每个特征图形，根据摄像机的透视变换系数和特征图形在拍摄图像中的拍摄位置，确定特征图形在投影屏幕上的第一目标投影位置。
根据透视变换系数和主画面中的参考点在拍摄图像中的拍摄位置，确定参考点在投影屏幕上的第二目标投影位置。
根据多个特征图形的第一目标投影位置和参考点的第二目标投影位置，对投影图像的投影位置进行校正。
综上所述，本公开实施例提供了一种激光投影设备，由于该激光投影设备可以根据透视变换系数、特征图形的拍摄位置以及主画面中的参考点的拍摄位置，确定出该特征图形的第一目标投影位置和该参考点的第二目标投影位置。之后，可以根据该多个特征图形的第一目标投影位置和参考点的第二目标投影位置对投影图像的投影位置进行校正。由此即便在激光投影设备的投影镜头发生畸变或者该激光投影设备发生位移的情况下，该投影显 示在投影屏幕上的投影图像也不会发生形变，从而确保投影图像的显示效果较好。
在一具体实施中，该参考点位于主画面的边界上，主画面的边界的颜色与目标图像中除主画面之外的区域的背景色不同。
在一具体实施中，该激光投影设备，用于：
根据多个特征图形中目标特征图形的第一目标投影位置、参考点的第二目标投影位置以及目标比值，确定目标图像的目标顶点在投影屏幕上的第三目标投影位置，目标图像的边界，主画面的边界，以及多个特征图形组成的图形均为四边形，参考点为主画面的边界的顶点。
根据目标顶点的第三目标投影位置和目标顶点在投影屏幕上的第一初始投影位置，对投影图像的投影位置进行校正。
其中，目标特征图形为与参考点的距离小于距离阈值的特征图形；目标比值与第二初始投影位置和第一初始投影位置的差值正相关，且与第三初始投影位置和第一初始投影位置的差值负相关。目标顶点为目标图像的多个顶点中距离参考点最近的顶点。第一初始投影位置，第二初始投影位置和第三初始投影位置分别为投影图像未发生形变时，目标顶点、目标特征图形和参考点在投影屏幕上的投影位置。
在一具体实施中，该目标比值可以包括第一比值和第二比值；该激光投影设备用于：
根据目标特征图形的第一目标投影位置的第一坐标、参考点的第二目标投影位置的第一坐标以及第一比值，确定目标顶点的第三目标投影位置的第一坐标。
根据目标特征图形的第一目标投影位置的第二坐标、参考点的第二目标投影位置的第二坐标以及第二比值，确定目标顶点的第三目标投影位置的第二坐标。
确定第三目标投影位置的第一坐标和第一初始投影位置的第一坐标的第一目标差值，以及第三目标投影位置的第一坐标相对于第一初始投影位置的第一坐标的第一偏移方向。
控制投影图像中的像素沿与第一偏移方向相反的方向移动第一目标差值。
确定第三目标投影位置的第二坐标和第一初始投影位置的第二坐标的第二目标差值，以及第三目标投影位置的第二坐标相对于第一初始投影位置的第二坐标的第二偏移方向。
控制投影图像中的像素沿与第二偏移方向相反的方向移动第二目标差值。
其中，第一比值为第一初始差值与第二初始差值的比值，第一初始差值为第二初始投影位置的第一坐标和第一初始投影位置的第一坐标的差值，第二初始差值为第三初始投影位置的第一坐标和第一初始投影位置的第一坐标的差值。该第二比值为第三初始差值与第四初始差值的比值，第三初始差值为第二初始投影位置的第二坐标和第一初始投影位置的第二坐标的差值，第四初始差值为第三初始投影位置的第二坐标和第一初始投影位置的第 二坐标的差值。
在一具体实施中，该激光投影设备还用于：
若每个特征图形的第一目标投影位置均位于投影屏幕内，则根据透视变换系数和主画面中的参考点在拍摄图像中的拍摄位置，确定参考点在投影屏幕上的第二目标投影位置。
在一具体实施中，该激光投影设备还用于：
若多个特征图形中任一特征图形的第一目标投影位置位于投影屏幕之外，则显示提示信息，提示信息用于提示投影图像的形变较大。
综上所述，本公开实施例提供了一种激光投影设备，由于该激光投影设备可以根据透视变换系数、特征图形的拍摄位置以及主画面中的参考点的拍摄位置，确定出该特征图形的第一目标投影位置和该参考点的第二目标投影位置。之后，可以根据该多个特征图形的第一目标投影位置和参考点的第二目标投影位置对投影图像的投影位置进行校正。由此即便在激光投影设备的投影镜头发生畸变或者该激光投影设备发生位移的情况下，该投影显示在投影屏幕上的投影图像也不会发生形变，从而确保投影图像的显示效果较好。
本公开实施例提供了一种激光投影设备，包括：存储器，处理器及存储在该存储器上的计算机程序，该处理器执行该计算机程序时实现上述方法实施例提供的投影图像的校正方法，例如图1或图4所示的方法。
本公开实施例提供了一种计算机可读存储介质，该计算机可读存储介质中存储有指令，该指令由处理器加载并执行以实现如上述方法实施例提供的投影图像的校正方法，例如图1或图4所示的方法。
本公开实施例提供了一种包含指令的计算机程序产品，当计算机程序产品在计算机上运行时，使得该计算机执行如上述方法实施例提供的投影图像的校正方法，例如图1或图4所示的方法。
在本公开实施例中，术语“第一”、“第二”、“第三”和“第四”仅用于描述目的，而不能理解为指示或暗示相对重要性。本公开实施例中术语“多个”的含义是指两个或两个以上。以上所述仅为本公开的可选实施例，并不用以限制本公开，凡在本公开的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本公开的保护范围之内。

Claims (10)

  1. 一种投影图像的校正方法，其特征在于，应用于激光投影设备，所述方法包括：
    响应于校正指令，在投影屏幕显示目标图像，所述目标图像包括主画面以及环绕所述主画面的多个特征图形，每个所述特征图形的颜色与所述目标图像中除所述主画面之外的区域的背景色不同；
    获取摄像机对所述投影屏幕进行拍摄得到的拍摄图像；
    对于每个所述特征图形，根据所述摄像机的透视变换系数和所述特征图形在所述拍摄图像中的拍摄位置，确定所述特征图形在所述投影屏幕上的第一目标投影位置；
    根据所述透视变换系数和所述主画面中的参考点在所述拍摄图像中的拍摄位置，确定所述参考点在所述投影屏幕上的第二目标投影位置；
    根据所述多个特征图形的第一目标投影位置和所述参考点的第二目标投影位置，对投影图像的投影位置进行校正。
  2. 根据权利要求1所述的方法，其特征在于，所述参考点位于所述主画面的边界上，所述主画面的边界的颜色与所述目标图像中除所述主画面之外的区域的背景色不同。
  3. 根据权利要求1所述的方法，其特征在于，所述目标图像的边界，所述主画面的边界，以及所述多个特征图形组成的图形均为多边形，所述参考点为所述主画面的边界的顶点；所述根据所述多个特征图形的第一目标投影位置和所述参考点的第二目标投影位置，对投影图像的投影位置进行校正，包括：
    根据所述多个特征图形中目标特征图形的第一目标投影位置、所述参考点的第二目标投影位置以及目标比值，确定所述目标图像的目标顶点在所述投影屏幕上的第三目标投影位置；
    根据所述目标顶点的第三目标投影位置和所述目标顶点在所述投影屏幕上的第一初始投影位置，对投影图像的投影位置进行校正；
    其中，所述目标特征图形为与所述参考点的距离小于距离阈值的特征图形；所述目标比值与第二初始投影位置和所述第一初始投影位置的差值正相关，且与第三初始投影位置和所述第一初始投影位置的差值负相关；所述目标顶点为所述目标图像的多个顶点中距离所述参考点最近的顶点；所述第一初始投影位置，所述第二初始投影位置和所述第三初始投影位置分别为所述投影图像未发生形变时，所述目标顶点、所述目标特征图形和所述参考点在所述投影屏幕上的投影位置。
  4. 根据权利要求3所述的方法，其特征在于，所述目标比值包括第一比值和第二比值；所述根据所述多个特征图形中目标特征图形的第一目标投影位置、所述参考点的第二目标投影位置以及目标比值，确定所述目标图像的目标顶点在所述投影屏幕上的第三目标投影位置，包括：
    根据所述目标特征图形的第一目标投影位置的第一坐标、所述参考点的第二目标投影位置的第一坐标以及第一比值，确定所述目标顶点的第三目标投影位置的第一坐标；
    根据所述目标特征图形的第一目标投影位置的第二坐标、所述参考点的第二目标投影位置的第二坐标以及第二比值，确定所述目标顶点的第三目标投影位置的第二坐标；
    所述根据所述目标顶点的第三目标投影位置和所述目标顶点在所述投影屏幕上的第一初始投影位置，对投影图像的投影位置进行校正，包括：
    确定所述第三目标投影位置的第一坐标和所述第一初始投影位置的第一坐标的第一目标差值，以及所述第三目标投影位置的第一坐标相对于所述第一初始投影位置的第一坐标的第一偏移方向；
    控制所述投影图像中的像素沿与所述第一偏移方向相反的方向移动所述第一目标差值；
    确定所述第三目标投影位置的第二坐标和所述第一初始投影位置的第二坐标的第二目标差值，以及所述第三目标投影位置的第二坐标相对于所述第一初始投影位置的第二坐标的第二偏移方向；
    控制所述投影图像中的像素沿与所述第二偏移方向相反的方向移动所述第二目标差值；
    其中，所述第一比值为第一初始差值与第二初始差值的比值，所述第一初始差值为所述第二初始投影位置的第一坐标和所述第一初始投影位置的第一坐标的差值，所述第二初始差值为所述第三初始投影位置的第一坐标和所述第一初始投影位置的第一坐标的差值；
    所述第二比值为所述第三初始差值与第四初始差值的比值，所述第三初始差值为所述第二初始投影位置的第二坐标和所述第一初始投影位置的第二坐标的差值，所述第四初始差值为所述第三初始投影位置的第二坐标和所述第一初始投影位置的第二坐标的差值。
  5. 根据权利要求1至4任一所述的方法，其特征在于，所述方法还包括：
    若所述多个特征图形的第一目标投影位置均位于所述投影屏幕内，则根据所述透视变换系数和所述主画面中的参考点在所述拍摄图像中的拍摄位置，确定所述参考点在所述投影屏幕上的第二目标投影位置。
  6. 根据权利要求5所述的方法，其特征在于，所述方法还包括：
    若所述多个特征图形中任一所述特征图形的第一目标投影位置位于所述投影屏幕之外，则显示提示信息，所述提示信息用于提示所述投影图像的形变较大。
  7. 一种激光投影设备，其特征在于，所述激光投影设备，用于：
    响应于校正指令，在投影屏幕显示目标图像，所述目标图像包括主画面以及环绕所述主画面的多个特征图形，每个所述特征图形的颜色与所述目标图像中除所述主画面之外的区域的背景色不同；
    获取摄像机对所述投影屏幕进行拍摄得到的拍摄图像；
    对于每个所述特征图形，根据所述摄像机的透视变换系数和所述特征图形在所述拍摄图像中的拍摄位置，确定所述特征图形在所述投影屏幕上的第一目标投影位置；
    根据所述透视变换系数和所述主画面中的参考点在所述拍摄图像中的拍摄位置，确定所述参考点在所述投影屏幕上的第二目标投影位置；
    根据所述多个特征图形的第一目标投影位置和所述参考点的第二目标投影位置，对投影图像的投影位置进行校正。
  8. 根据权利要求7所述的激光投影设备，其特征在于，所述参考点位于所述主画面的边界上，所述主画面的边界的颜色与所述目标图像中除所述主画面之外的区域的背景色不同。
  9. 根据权利要求7所述的激光投影设备，其特征在于，所述激光投影设备，用于：
    根据所述多个特征图形中目标特征图形的第一目标投影位置、所述参考点的第二目标投影位置以及目标比值，确定所述目标图像的目标顶点在所述投影屏幕上的第三目标投影位置，所述目标图像的边界，所述主画面的边界，以及所述多个特征图形组成的图形均为四边形，所述参考点为所述主画面的边界的顶点；
    根据所述目标顶点的第三目标投影位置和所述目标顶点在所述投影屏幕上的第一初始投影位置，对投影图像的投影位置进行校正；
    其中，所述目标特征图形为与所述参考点的距离小于距离阈值的特征图形；所述目标比值与第二初始投影位置和所述第一初始投影位置的差值正相关，且与第三初始投影位置和所述第一初始投影位置的差值负相关；所述目标顶点为所述目标图像的多个顶点中距离所述参考点最近的顶点；所述第一初始投影位置，所述第二初始投影位置和所述第三初始投影位置分别为所述投影图像未发生形变时，所述目标顶点、所述目标特征图形和所述参考点在所述投影屏幕上的投影位置。
  10. 根据权利要求9所述的激光投影设备，其特征在于，所述目标比值包括第一比值和第二比值；所述激光投影设备，用于：
    根据所述目标特征图形的第一目标投影位置的第一坐标、所述参考点的第二目标投影位置的第一坐标以及第一比值，确定所述目标顶点的第三目标投影位置的第一坐标；
    根据所述目标特征图形的第一目标投影位置的第二坐标、所述参考点的第二目标投影位置的第二坐标以及第二比值，确定所述目标顶点的第三目标投影位置的第二坐标；
    确定所述第三目标投影位置的第一坐标和所述第一初始投影位置的第一坐标的第一目标差值，以及所述第三目标投影位置的第一坐标相对于所述第一初始投影位置的第一坐标的第一偏移方向；
    控制所述投影图像中的像素沿与所述第一偏移方向相反的方向移动所述第一目标差值；
    确定所述第三目标投影位置的第二坐标和所述第一初始投影位置的第二坐标的第二目标差值，以及所述第三目标投影位置的第二坐标相对于所述第一初始投影位置的第二坐标的第二偏移方向；
    控制所述投影图像中的像素沿与所述第二偏移方向相反的方向移动所述第二目标差值；
    其中，所述第一比值为第一初始差值与第二初始差值的比值，所述第一初始差值为所述第二初始投影位置的第一坐标和所述第一初始投影位置的第一坐标的差值，所述第二初始差值为所述第三初始投影位置的第一坐标和所述第一初始投影位置的第一坐标的差值；
    所述第二比值为所述第三初始差值与所述第四初始差值的比值，所述第三初始差值为所述第二初始投影位置的第二坐标和所述第一初始投影位置的第二坐标的差值，所述第四初始差值为所述第三初始投影位置的第二坐标和所述第一初始投影位置的第二坐标的差值。
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