CN113055663A - Projection image correction method and laser projection device - Google Patents

Projection image correction method and laser projection device Download PDF

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Publication number
CN113055663A
CN113055663A CN202110348649.2A CN202110348649A CN113055663A CN 113055663 A CN113055663 A CN 113055663A CN 202110348649 A CN202110348649 A CN 202110348649A CN 113055663 A CN113055663 A CN 113055663A
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target
projection
projection position
initial
coordinate
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CN113055663B (en
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张冬冬
唐甜甜
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Qingdao Hisense Laser Display Co Ltd
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Qingdao Hisense Laser Display Co Ltd
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Priority to PCT/CN2022/082627 priority patent/WO2022206527A1/en
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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

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
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  • Geometry (AREA)
  • Optics & Photonics (AREA)
  • Projection Apparatus (AREA)
  • Transforming Electric Information Into Light Information (AREA)
  • Controls And Circuits For Display Device (AREA)

Abstract

The application discloses a projected image correction method and laser projection equipment. Belonging to the field of projection display. The correction method can determine the first target projection position of the characteristic graph and the second target projection position of the reference point according to the perspective transformation coefficient, the shooting position of the characteristic graph and the shooting position of the reference point in the main picture. And correcting the projection position of the projection image according to the first target projection positions 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 equipment is distorted or the laser projection equipment is displaced, the projection image projected and displayed on the projection screen cannot be deformed, and the good display effect of the projection image is ensured. Further, since the main screen is included in the target image displayed on the projection screen in the process of correcting the projection image, continuous playback of the main screen can be ensured.

Description

Projection image correction method and laser projection device
Technical Field
The present disclosure relates to the field of projection display, and in particular, to a method for correcting a projected image and a laser projection apparatus.
Background
Currently, a laser projection device can project and display a projection image onto a projection screen. However, if the projection lens of the laser projection apparatus is distorted, the projection image projected and displayed on the projection screen by the laser projection apparatus is distorted, and the display effect of the displayed projection image is poor.
Disclosure of Invention
The embodiment of the disclosure provides a projected image correction method and a laser projection device, which can solve the problem of poor display effect of a projected image displayed in the related art. The technical scheme is as follows:
in one aspect, a method for correcting a projected image is provided, and is applied to a laser projection device, and the method includes:
in response to a correction instruction, displaying a target image on a projection screen, wherein the target image comprises a main picture and a plurality of characteristic graphs surrounding the main picture, and the color of each characteristic graph is different from the background color of a region except the main picture in the target image;
acquiring a shot image obtained by shooting the projection screen by a camera;
for each feature pattern, determining a first target projection position of the feature pattern on the projection screen according to a perspective transformation coefficient of the camera and a shooting position of the feature pattern in the shot image;
determining a 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 picture in the shot image;
and correcting the projection position of the projection image according to the first target projection positions of the plurality of characteristic graphs and the second target projection position of the reference point.
Optionally, the reference point is located on a boundary of the main picture, and a color of the boundary of the main picture is different from a background color of a region of the target image other than the main picture.
Optionally, the boundary of the target image, the boundary of the main picture, and a graph formed by the plurality of feature graphs are polygons, and the reference point is a vertex of the boundary of the main picture; the correcting the projection position of the projection image according to the first target projection positions of the plurality of feature patterns and the second target projection position of the reference point includes:
determining a third target projection position of a target vertex of the target image on the projection screen according to a first target projection position of a target feature graph in the plurality of feature graphs, a second target projection position of the reference point and a target ratio;
correcting the projection position of the projection 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 target feature graph is a feature graph of which the distance from the reference point is smaller than a distance threshold value; 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 in the multiple vertexes of the target image; the first initial projection position, the second initial projection position and the third initial projection position are respectively projection positions of the target vertex, the target feature graph and the reference point on the projection screen when the projection image is not deformed.
Optionally, the target ratio includes a first ratio and a second ratio; determining a third target projection position of a target vertex of the target image on the projection screen according to a first target projection position of a target feature pattern in the plurality of feature patterns, a second target projection position of the reference point, and a target ratio, including:
determining a first coordinate of a third target projection position of the target vertex according to the first coordinate of the first target projection position of the target feature graph, the first coordinate of the second target projection position of the reference point and a first ratio;
determining a second coordinate of a third target projection position of the target vertex according to a second coordinate of the first target projection position of the target feature graph, a second coordinate of the second target projection position of the reference point and a second ratio;
the correcting the projection position of the projection 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 includes:
determining a first target difference value of the first coordinate of the third target projection position and the first coordinate of the first initial projection position, and a first offset direction of the first coordinate of the third target projection position relative to the first coordinate of the first initial projection position;
controlling pixels in the projected image to move the first target difference in a direction opposite the first offset direction;
determining a second target difference value of the second coordinate of the third target projection position and the second coordinate of the first initial projection position, and a second offset direction of the second coordinate of the third target projection position relative to the second coordinate of the first initial projection position;
controlling pixels in the projected image to move the second target difference in a direction opposite the second offset direction;
the first ratio is a ratio of a first initial difference value and a second initial difference value, the first initial difference value is a difference value of a first coordinate of the second initial projection position and a first coordinate of the first initial projection position, and the second initial difference value is a difference value of a first coordinate of the third initial projection position and a first coordinate of the first initial projection position;
the second ratio is a ratio of the third initial difference to the fourth initial difference, the third initial difference is a difference between the second coordinate of the second initial projection position and the second coordinate of the first initial projection position, and the fourth initial difference is a difference between the second coordinate of the third initial projection position and the second coordinate of the first initial projection position.
Optionally, the method further includes:
and if the first target projection position of each feature pattern is located in the projection screen, determining a 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 picture in the shot image.
Optionally, the method further includes:
and if the first target projection position of any one of the feature graphs is positioned outside the projection screen, displaying prompt information, wherein the prompt information is used for prompting that the deformation of the projection image is larger.
In another aspect, there is provided a laser projection apparatus, configured to:
in response to a correction instruction, displaying a target image on a projection screen, wherein the target image comprises a main picture and a plurality of characteristic graphs surrounding the main picture, and the color of each characteristic graph is different from the background color of a region except the main picture in the target image;
acquiring a shot image obtained by shooting the projection screen by a camera;
for each feature pattern, determining a first target projection position of the feature pattern on the projection screen according to a perspective transformation coefficient of the camera and a shooting position of the feature pattern in the shot image;
determining a 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 picture in the shot image;
and correcting the projection position of the projection image according to the first target projection positions of the plurality of characteristic graphs and the second target projection position of the reference point.
Optionally, the reference point is located on a boundary of the main picture, and a color of the boundary of the main picture is different from a background color of a region of the target image other than the main picture.
Optionally, the laser projection apparatus is configured to:
determining a third target projection position of a target vertex of the target image on the projection screen, a boundary of the target image, a boundary of the main picture and a picture formed by the plurality of feature pictures are polygons according to a first target projection position of a target feature picture, a second target projection position of the reference point and a target ratio in the plurality of feature pictures, wherein the reference point is a vertex of the boundary of the main picture;
correcting the projection position of the projection 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 target feature graph is a feature graph of which the distance from the reference point is smaller than a distance threshold value; 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 in the multiple vertexes of the target image; the first initial projection position, the second initial projection position and the third initial projection position are respectively projection positions of the target vertex, the target feature graph and the reference point on the projection screen when the projection image is not deformed.
Optionally, the target ratio includes a first ratio and a second ratio; the laser projection device is configured to:
determining a first coordinate of a third target projection position of the target vertex according to the first coordinate of the first target projection position of the target feature graph, the first coordinate of the second target projection position of the reference point and a first ratio;
determining a second coordinate of a third target projection position of the target vertex according to a second coordinate of the first target projection position of the target feature graph, a second coordinate of the second target projection position of the reference point and a second ratio;
determining a first target difference value of the first coordinate of the third target projection position and the first coordinate of the first initial projection position, and a first offset direction of the first coordinate of the third target projection position relative to the first coordinate of the first initial projection position;
controlling pixels in the projected image to move the first target difference in a direction opposite the first offset direction;
determining a second target difference value of the second coordinate of the third target projection position and the second coordinate of the first initial projection position, and a second offset direction of the second coordinate of the third target projection position relative to the second coordinate of the first initial projection position;
controlling pixels in the projected image to move the second target difference in a direction opposite the second offset direction;
the first ratio is a ratio of a first initial difference value and a second initial difference value, the first initial difference value is a difference value of a first coordinate of the second initial projection position and a first coordinate of the first initial projection position, and the second initial difference value is a difference value of a first coordinate of the third initial projection position and a first coordinate of the first initial projection position;
the second ratio is a ratio of the third initial difference to the fourth initial difference, the third initial difference is a difference between the second coordinate of the second initial projection position and the second coordinate of the first initial projection position, and the fourth initial difference is a difference between the second coordinate of the third initial projection position and the second coordinate of the first initial projection position.
In yet another aspect, there is provided a laser projection apparatus including: a memory, a processor and a computer program stored on the memory, the processor implementing the method of correcting a projected image as described in the above aspect when executing the computer program.
In yet another aspect, a computer-readable storage medium having instructions stored therein, the instructions being loaded and executed by a processor to implement the method of correcting a projected image as described in the above aspect is provided.
In a further aspect, there is provided a computer program product containing instructions which, when run on the computer, cause the computer to perform the method of correcting a projected image of the above aspect.
The beneficial effects brought by the technical scheme provided by the embodiment of the disclosure at least comprise:
the embodiment of the disclosure provides a projection image correction method and a laser projection device, and the correction method can determine a first target projection position of a characteristic graph and a second target projection position of a reference point according to a perspective transformation coefficient, a shooting position of the characteristic graph and a shooting position of the reference point in a main picture. Thereafter, the projection position of the projection image may be corrected based on the first target projection positions 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 equipment is distorted or the laser projection equipment is displaced, the projection image projected and displayed on the projection screen cannot be deformed, and the good display effect of the projection image is ensured.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
Fig. 1 is a flowchart of a method for correcting a projected image according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of a laser projection apparatus provided in an embodiment of the present disclosure;
FIG. 3 is a schematic diagram of a structure of a target image according to an embodiment of the present disclosure;
FIG. 4 is a flowchart of a method for correcting a projected image according to an embodiment of the present disclosure;
FIG. 5 is a schematic diagram of a feature pattern provided by embodiments of the present disclosure;
FIG. 6 is a diagram illustrating deformation of a projection image according to 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 deformation of a further projection image provided by the related art;
fig. 9 is a schematic structural diagram of another laser projection apparatus provided in the embodiments of the present disclosure.
Detailed Description
To make the objects, technical solutions and advantages of the present disclosure more apparent, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.
Fig. 1 is a flowchart of a method for correcting a projection image according to an embodiment of the present disclosure. The correction method can be applied to a laser projection apparatus. As shown in fig. 1, the method may include:
and step 101, responding to a correction instruction, and displaying a target image on a projection screen.
Referring to fig. 2, the laser projection apparatus 10 may project a display target image on a projection screen 20 in response to a correction instruction. Here, referring to fig. 3, the target image 30 may include a main screen 301 and a plurality of feature patterns (e.g., a feature pattern 302a, a feature pattern 302b, and a feature pattern 302c) surrounding the main screen 301. The color of each feature pattern is different from the background color of the region other than the main screen 301 in the target image 30. For example, referring to fig. 3, the color of each feature pattern may be black, and the background color of the region other than the home screen 301 in the target image 30 may be white.
In the process of projecting and displaying the target image, the laser projection equipment can keep the playing state of the main picture in the target image unchanged, thereby realizing the correction of the projection position of the projected image, ensuring the playing continuity of the main picture and further ensuring the watching continuity of a user.
And 102, acquiring a shot image obtained by shooting the projection screen by the camera.
Referring to fig. 2, a camera 40 may be provided on the laser projection device 10. The laser projection device can send a shooting instruction to the camera after the target image is projected and displayed on the projection screen. After receiving the shooting instruction, the camera may shoot the projection screen 20 to obtain a shot image, and send the shot image to the laser projection device 10, so that the laser projection device 10 may obtain the shot image.
Or the camera may be independent of the laser projection device, and the user may control the camera to shoot the projection screen to obtain a shot image, and control the camera to send the shot image to the laser projection device, so that the laser projection device may acquire the shot image.
And 103, determining the projection position of the first target 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 for each feature pattern.
After the laser projection device acquires the shot image, for each feature pattern, the laser projection device may determine a first target projection position of the feature pattern on the projection screen according to the perspective transformation coefficient of the camera and the shot position of the feature pattern in the shot image.
The perspective transformation coefficient can transform the position of any point in the projection screen to the position in the captured image, that is, the perspective transformation coefficient is a transformation coefficient 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. Alternatively, the projection screen may be polygonal, for example rectangular.
And step 104, determining the projection position of the second target 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 picture in the shot image.
After the laser projection equipment acquires the shot image, the second target projection position of the reference point on the projection screen can be determined according to the perspective transformation coefficient of the camera and the shooting position of the reference point in the main picture in the shot image. The reference point may be located on a boundary of the main picture, or the reference point may be a center point of the main picture.
And 105, correcting the projection position of the projection image according to the first target projection positions of the plurality of characteristic graphs and the second target projection position of the reference point.
The laser projection apparatus may correct the projection position of the projection image based on the first target projection positions of the plurality of feature patterns and the second target projection positions of the reference points after determining the first target projection positions of the plurality of feature patterns and the second target projection positions of the reference points.
Optionally, the laser projection device may determine a 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 pattern in the plurality of feature patterns and the second target projection position of the reference point. Furthermore, the projection position of the projection image may be corrected based on the third target projection position of the target vertex and the first initial projection position of the target vertex on the projection screen. For example, 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 to achieve 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 projection image is not deformed.
In summary, the embodiment of the present disclosure provides a method for correcting a projection image, which can determine a first target projection position of a feature pattern and a second target projection position of a reference point according to a perspective transformation coefficient, a shooting position of the feature pattern, and a shooting position of the reference point in a main picture. Thereafter, the projection position of the projection image may be corrected based on the first target projection positions 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 equipment is distorted or the laser projection equipment is displaced, the projection image projected and displayed on the projection screen cannot be deformed, and the good display effect of the projection image is ensured.
In addition, in the process of correcting the projected image, the target image displayed in the projection screen comprises the main picture, so that the continuous playing of the main picture can be ensured, and the influence of the correction flow of the projected image on the playing continuity of the main picture is avoided.
Fig. 4 is a flowchart of another method for correcting a projection image according to an embodiment of the present disclosure. The correction method can be applied to a laser projection apparatus. As shown in fig. 4, the method may include:
step 401, in response to the correction instruction, displaying the target image on the projection screen.
Referring to fig. 2, the laser projection apparatus 10 may project a display target image on a projection screen 20 in response to a correction instruction. The target image may include a main picture and a plurality of feature patterns surrounding the main picture, each feature pattern having a color different from a background color of a region of the target image other than the main picture, thereby ensuring that the laser projection apparatus can recognize the feature pattern from the captured image after the captured image is acquired. Alternatively, the feature pattern may be a quadrangle, a cross, or the like.
For example, referring to fig. 3, the target image 30 may include 12 feature patterns (e.g., a feature pattern 302a, a feature pattern 302b, and a feature pattern 302c) surrounding the main screen 301, and the 12 feature patterns may all be cross-shaped. The color of each feature pattern may be black, and the background color of the region other than the main screen 301 in the target image 30 may be white.
In the embodiment of the disclosure, the laser projection device may keep the playing state of the main picture in the target image unchanged during the process of displaying the target image, thereby realizing the correction of the projection position of the projection image, and simultaneously ensuring the playing continuity of the main picture, and further ensuring the viewing continuity of the user.
Alternatively, the correction instruction may be triggered by the user through a projection client installed in the terminal. The display interface of the projection client may display a correction button, and the projection client may generate a correction instruction after detecting a click operation of a user on the correction button. The projection client may then send the correction instructions 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 to the projection screen in response to the correction instruction.
Or, the correction instruction may be triggered by a user through a remote controller, and the laser projection device may, after receiving the correction instruction sent by the remote controller, project and display the target image on the projection screen in response to the correction instruction.
Or, a correction button may be disposed on the laser projection device, and the laser projection device may generate a correction instruction after detecting a click operation of a user on the correction button, and may further project and display the target image to the projection screen in response to the correction instruction.
Alternatively, the laser projection device may periodically generate a correction instruction, and may project and display the target image to the projection screen in response to the correction instruction. That is, the laser projection apparatus may periodically perform the correction procedure of the target image.
And 402, acquiring a shot image obtained by shooting the projection screen by the camera.
Referring to fig. 2, a camera 40 may be disposed on the laser projection device 10, and the camera 40 may be connected to the laser projection device 10 by means of a Universal Serial Bus (USB). The laser projection apparatus 10 may transmit a shooting instruction to the camera 40 after projecting and displaying the target image onto the projection screen 20. After receiving the shooting instruction, the camera 40 may shoot the projection screen 20 to obtain a shot image, and send the shot image to the laser projection apparatus 10, so that the laser projection apparatus 10 may obtain the shot image.
Or the camera may be independent of the laser projection device, and the user may control the camera to shoot the projection screen to obtain a shot image, and control the camera to send the shot image to the laser projection device, so that the laser projection device may acquire the shot image.
And step 403, determining the projection position of the first target 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 for each feature pattern.
In the disclosed embodiment, the projection screen may be polygonal. The laser projection apparatus may determine the photographed positions of the plurality of vertices of the projection screen in the photographed image after acquiring the photographed image, and may determine the perspective transformation coefficient of the camera according to the initial positions of the plurality of vertices of the projection screen and the photographed positions of the plurality of vertices of the projection screen in the photographed image. Then, for each feature pattern, the laser projection device may determine a first target projection position of the feature pattern on the projection screen based on the perspective transformation coefficient of the camera and the shot position of the feature pattern in the shot image.
The perspective transformation coefficient can transform the position of any point in the projection screen into the position in the shot image, namely the perspective transformation coefficient is a variation coefficient between the screen coordinate system of the projection screen and the image coordinate system of the shot 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.
Alternatively, the projection screen may be quadrilateral, for example rectangular. Accordingly, 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 an upper left vertex of the projection screen, the second vertex may be an upper right vertex of the projection screen, the third vertex may be a lower left vertex of the projection screen, and the fourth vertex may be a lower right vertex of the projection screen.
Optionally, the frame of the projection screen may include an inner frame and an outer frame, and the four vertices may be vertices of the inner frame or vertices of the outer frame, which is not limited in this disclosure.
Wherein 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, y 1). The shooting position of the second peak is (a2, b2), and the initial position of the second peak is (x2, y 2). The shooting position of the third vertex is (a3, b3), and the initial position of the third vertex is (x3, y 3). The imaging position of the fourth vertex is (a2, b2), and the initial position of the fourth vertex is (x4, y 4). The initial positions of the four vertices, the shooting positions of the four vertices, and the perspective transformation coefficients k0 to k7 may satisfy:
Figure BDA0003001645520000111
based on the above formula, the laser projection apparatus can determine 8 equations in the following equations (1) to (8), and can determine the perspective transformation coefficients k0 to k7 by solving the 8 equations.
Equation (1): a1-k 0 × x1+ k1 × y1+ k2-k6 × x1 × a1-k7 × y1 × a 1;
equation (2): b1 ═ k3 × x1+ k4 × y1+ k5-k6 × x1 × b1-k7 × y1 × b 1;
equation (3): a2-k 0 × x2+ k1 × y2+ k2-k6 × x2 × a2-k7 × y2 × a 2;
equation (4): b2 ═ k3 × x2+ k4 × y2+ k5-k6 × x2 × b2-k7 × y2 × b 2;
equation (5): a3-k 0 × x3+ k1 × y3+ k2-k6 × x3 × a3-k7 × y3 × a 3;
equation (6): b3 ═ k3 × x3+ k4 × y3+ k5-k6 × x3 × b3-k7 × y3 × b 3;
equation (7): a4-k 0 × x4+ k1 × y4+ k2-k6 × x4 × a4-k7 × y4 × a 4;
equation (8): b4-k 3 × x4+ k4 × y4+ k5-k6 × x4 × b4-k7 × y4 × b 4.
After determining the plurality of perspective transformation coefficients, the laser projection device may determine a perspective transformation matrix from the plurality of perspective transformation coefficients, and may determine an inverse K of the perspective transformation matrix-1. For each feature pattern, the laser projection device may transform the inverse K of the matrix from the perspective-1And the shooting position of the characteristic graph, and determining the projection position of the first target of the characteristic graph on the projection screen.
Wherein the perspective transformation matrix K and the inverse matrix K of the perspective transformation matrix-1Each may be a3 × 3 matrix, the K × K-1E is a3 × 3 identity matrix. The perspective transformation matrix K satisfies:
Figure BDA0003001645520000112
inverse K of the perspective transformation matrix-1Satisfies the following conditions: the
Figure BDA0003001645520000113
The first target projection position (X1, Y1) of the characteristic pattern with the shooting position (a, b) on the projection screen in the shot image satisfies the following conditions: x1 ═ t11×w×a+t12×w×b+t13×w；Y1＝t21×w×a+t22×w×b+t23X.w. The w satisfies:
Figure BDA0003001645520000114
tijis an inverse matrix K-1In the ith row and the jth column, i and j are positive integers less than or equal to 3.
In the embodiment of the present disclosure, 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. For each shot image, the laser projection device determines a perspective transformation coefficient of the camera based on the shot image, and determines a first target projection position of the feature pattern based on the perspective transformation coefficient and the shot position of the feature pattern, thereby improving the accuracy of determining the first target projection position of the feature pattern.
Optionally, the first target projection position of each feature pattern is a projection position of the feature pattern in a screen coordinate system of the projection screen, and the initial positions of the vertices of the projection screen may be positions of the vertices in the screen coordinate system. The shooting position of each feature graph is the position of the feature graph in an image coordinate system, and the shooting positions of the vertexes of the projection screen are the positions of the vertexes in the image coordinate system.
The origin of the screen coordinate system is the central 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 row direction of the projection screen. The origin of the image coordinate system is the central point of the shot image, the horizontal axis of the image coordinate system is parallel to the pixel row direction of the shot image, and the vertical axis of the image coordinate system is parallel to the pixel row direction of the shot image.
In the embodiment of the present disclosure, when determining the shooting positions of the plurality of feature patterns and the plurality of vertices of the projection screen, the laser projection apparatus may perform gray processing on the shot image to obtain a gray image. Then, the laser projection apparatus may determine a photographing position of each feature pattern of the projection screen and photographing positions of a plurality of vertexes of the projection screen in the photographed image based on the gradation value of each pixel in the gradation image.
Wherein the gray scale value range of each pixel in the gray scale image may be [0, 255 ]. The pixel with the gray value of 0 appears black in the gray image, and the pixel with the gray value of 255 appears white in the gray image.
In the embodiment of the present disclosure, each feature pattern may be composed of a plurality of target pixels included in one target pixel group. Because the distance between two adjacent feature patterns is in the first pixel range, the distance between two adjacent target pixel groups is in the first pixel range, and the distance between any two adjacent target pixels in the plurality of target pixels included in each target pixel group is in the second pixel range. The first pixel range and the second pixel range are both fixed ranges pre-stored in the laser projection equipment.
The laser projection device may identify a plurality of pixels in the grayscale image, each of which has a grayscale value smaller than the first grayscale threshold, and may determine a plurality of target pixel groups from the plurality of pixels, so as to obtain the shooting positions of the plurality of target pixels included in each of the target pixel groups. Thereafter, referring to fig. 5, the laser projection apparatus may determine the photographing position of the vertex pixel (e.g., vertex pixel a shown in fig. 5) of the feature pattern formed by each target pixel group in the photographed image as the photographing position of the feature pattern corresponding to the target pixel group. Alternatively, the laser projection apparatus 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 apparatus may determine the shooting positions of a plurality of vertex pixels of the feature pattern surrounded by the target pixel group in the shot image, and may determine the average value of the shooting positions of the plurality of vertex pixels as the shooting position of the feature pattern corresponding to the target pixel group. Wherein, the first gray value threshold is a fixed range pre-stored in the laser projection device.
The embodiments of the present disclosure take a plurality of vertices of a projection screen as vertices of an outer frame as an example. If the color of the frame of the projection screen is black, the laser projection device may determine, as an edge pixel, a pixel in the grayscale image having a grayscale value smaller than the second grayscale value threshold, where the shape of the pattern formed by the edge pixels is a quadrangle, and an absolute value of a position of each edge pixel is greater than an absolute value of a position of any feature pattern. The laser projection apparatus may then determine the position of the edge pixel in the grayscale image as the position of each pixel on the frame of the projection screen in the captured image, and may determine the positions of four points of the edge pixel that are farthest from the center point of the grayscale image as the captured positions of the four vertices. The second gray value threshold may be a fixed value pre-stored in the laser projection apparatus.
Because the colors of the inner frame and the outer frame of the projection screen are similar, the gray value of the pixels between the inner frame and the outer frame of the projection screen is in a fixed range, and the positions of the edge pixels in the gray image are determined to be the positions of each pixel on the inner frame and the outer frame of the projection screen in the shot image by adopting the method.
And step 404, detecting whether the first target projection positions of the plurality of characteristic graphs are all located in the projection screen.
The laser projection device may detect whether the first target projection position of the plurality of feature patterns is located within the projection screen after determining the first target projection position of each feature pattern. If it is detected that the first target projection positions of the plurality of feature patterns are all located in the projection screen, the laser projection device may determine that the deformation of the projection image is small, and after the projection positions of the projection image are corrected, the laser projection device may perform step 405 if the image information of the projection image is less lost. If it is detected that the first target projection position of any feature pattern is located outside the projection screen, the laser projection device may determine that the deformation of the projection image is large, and after the projection position of the projection image is corrected, the image information of the projection image is lost more, so the laser projection device may perform step 408.
For each feature pattern, the laser projection device may detect whether a spacing between a first target projection location of the feature pattern and an initial location of a center point of the projection screen is less than a first pixel threshold. If less than the first pixel threshold is detected, it may be determined that the first target projection location of the feature pattern is within the projection screen. If the first pixel threshold value or more is detected, the first target projection position of the feature pattern can be determined to be outside the projection screen. The first pixel threshold is a fixed value pre-stored in the laser projection device.
And step 405, determining a 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 picture in the shot image.
After determining that the first target projection positions of the plurality of characteristic patterns are all located in the projection screen, the laser projection device can determine a 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 picture in the shot image.
In the disclosed embodiment, the second target projection position (X2, Y2) on the projection screen of the reference point whose shooting position is (c, d) in the shot image satisfies: x2 ═ t11×w×c+t12×w×d+t13×w；Y2＝t21×w×c+t22×w×d+t23X.w. The w satisfies:
Figure BDA0003001645520000141
alternatively, 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 boundary of the main picture is different from the background color of the region other than the main picture in the target image, thereby ensuring that the laser projection apparatus can recognize the reference point.
Since the color of the boundary of the main picture is different from the background color of the region other than the main picture in the target image, the laser projection apparatus may determine a plurality of pixels having a gray value smaller than the third gray value threshold value in the gray image, and determine boundary pixels on the boundary of the main picture from among the plurality of pixels. The absolute value of the position of each boundary pixel is smaller than that of any feature pattern, and the pattern formed by the boundary pixels is a quadrangle. The laser projection device may then 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. If the boundary of the main picture is a quadrangle and the reference point is a vertex on the boundary, the laser projection device may determine the positions of four points farthest from the center point of the main picture in the boundary pixels as the shooting positions of the four vertices on the boundary, so as to determine the shooting position of the reference point. The third gray value threshold may be a fixed value pre-stored in the laser projection apparatus.
And step 406, determining a 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 in the plurality of feature graphs, the second target projection position of the reference point and the target ratio.
After the laser projection device determines the first target projection positions of the plurality of feature patterns and the second target projection positions of the reference points, the laser projection device may determine a 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 pattern, the second target projection position of the reference point, and the target ratio in the plurality of feature patterns.
The boundary of the target image, the boundary of the main picture and the graph formed by the characteristic graphs are all quadrangles. The reference point may be a vertex of a boundary of the main picture. The target feature pattern is a feature pattern whose distance from the reference point is less than a distance threshold. The target ratio is positively correlated with the difference between the second initial projection position and the first initial projection position, and negatively correlated with the difference between the third initial projection position and the first initial projection position. The target vertex is a vertex closest to a reference point in a plurality of vertexes of the target image, and the first initial projection position, the second initial projection position and the third initial projection position are projection positions of the target vertex, the target feature graph and the reference point on the projection screen when the projection image is not deformed. The distance threshold may be a fixed value pre-stored in the laser projection device.
For example, referring to fig. 2, the reference point 301a may be a top right vertex of the boundary of the main picture 301, and the target vertex may be a vertex closest to the reference point 301a among the vertices of the target image 30, that is, a top right vertex in the target image 30. The target feature pattern is a feature pattern whose distance from the reference point 301a is smaller than a distance threshold. That is, the target feature pattern may be the feature pattern 302a, or the feature pattern 302b, or the feature pattern 302 c. Alternatively, the target feature pattern may include the feature pattern 302a, the feature pattern 302b, and the feature pattern 302 c.
Alternatively, the target ratio may include a first ratio and a second ratio, and when determining a third target projection position of a target vertex of the target image on the projection screen according to the first target projection position of the target feature pattern, the second target projection position of the reference point, and the target ratio among the plurality of feature patterns, the laser projection apparatus may determine the first coordinate z3 of the third target projection position of the target vertex according to the first coordinate z1 of the first target projection position of the target feature pattern, the first coordinate z2 of the second target projection position of the reference point, and the first ratio S1. It is composed ofThe first coordinate of the projection position of the third target satisfies:
Figure BDA0003001645520000151
and, the laser projection apparatus may determine the second coordinates g3 of the third target projection position of the target vertexes from the second coordinates g1 of the first target projection position of the target feature pattern, the second coordinates g2 of the second target projection position of the reference point, and the second ratio S2. Wherein the first coordinate of the projection position of the third target satisfies:
Figure BDA0003001645520000152
alternatively, the first coordinate may be an abscissa and the second coordinate may be an ordinate.
The first ratio and the second ratio are fixed values pre-stored in the laser projection equipment. The first ratio S1 can be the ratio of the first initial difference R to the second initial difference P, i.e. the first ratio S1 satisfies:
Figure BDA0003001645520000153
the first initial difference R is a difference between the first coordinate R1 of the second initial projection position and the first coordinate R2 of the first initial projection position, that is, the first initial difference R satisfies: R1-R2. The second initial difference P is a difference between the first coordinate P of the third initial projection position and the first coordinate r2 of the first initial projection position, that is, the second initial difference P satisfies: p-r 2.
The second ratio S2 can be the ratio of the third initial difference H to the fourth initial difference Q, i.e. the second ratio S2 satisfies:
Figure BDA0003001645520000161
the third initial difference H is a difference between the second coordinate H1 of the second initial projection position and the second coordinate H2 of the first initial projection position, that is, the third initial difference H satisfies: H-H1-H2. The fourth initial difference Q is a difference between the second coordinate Q of the third initial projection position and the second coordinate h2 of the first initial projection position, that is, the fourth initial difference Q satisfies: theQ＝q-h2。
Optionally, if the number of the target feature patterns is greater than 1, the first coordinate z1 of the first target projection position may be an average of first coordinates of first target projection positions of the plurality of target feature patterns, and the second coordinate g1 of the first target projection position may be an average of second coordinates of second target projection positions of the plurality of target feature patterns.
Step 407, correcting the projection position of the projection 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.
After determining the third target projection position of the target vertex, the laser projection device may correct the projection position of the projection 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.
Optionally, when the laser projection device corrects the projection position of the projection image according to a third target projection position of the target vertex and a first initial projection position of the target vertex on the projection screen, a first target difference between a first coordinate of the third target projection position and a first coordinate of the first initial projection position and a first offset direction of the first coordinate of the third target projection position relative to the first coordinate of the first initial projection position may be determined. The pixels in the projected image may then be controlled to move the first target difference in a direction opposite the first offset direction.
Assuming that the target vertex of the target image is the upper right vertex of the target image, and the absolute value of the first coordinate of the third target projection position is greater than the absolute value of the first coordinate of the first initial projection position, referring to fig. 2, the laser projection apparatus may determine the first offset direction as a direction s1 parallel to the pixel row direction and away from the origin of the screen coordinate system, and may control the pixels in the projection image to be shifted by the first target difference value in a direction s2 parallel to the pixel row direction and close to the origin of the screen coordinate system. If the absolute value of the first coordinate of the third target projection position is less than the absolute value of the first coordinate of the first initial projection position, referring to fig. 2, the laser projection apparatus may determine that the first offset direction is a direction s2 parallel to the pixel row direction and close to the origin of the screen coordinate system, and the laser projection apparatus may control the pixels in the projection image to be shifted by the first target difference value in a direction s1 parallel to the pixel row direction and far from the origin of the screen coordinate system.
The laser projection device may also determine a second target difference value of a second coordinate of the third target projection location and a second coordinate of the first initial projection location, and a second offset direction of the second coordinate of the third target projection location relative to the second coordinate of the first initial projection location. The pixels in the projected image may then be controlled to move the second target difference in a direction opposite the second offset direction.
Assuming that the target vertex of the target image is the upper right vertex of the target image, and the absolute value of the second coordinate of the third target projection position is greater than the absolute value of the second coordinate of the first initial projection position, referring to fig. 2, the laser projection apparatus may determine that the second offset direction is a direction s3 parallel to the pixel column direction and away from the origin of the screen coordinate system, and may control the pixels in the projection image to be shifted by the second target difference value in a direction s4 parallel to the pixel column direction and close to the origin of the screen coordinate system. If the absolute value of the second coordinate of the third target projection position is less than the absolute value of the second coordinate of the first initial projection position, referring to fig. 2, the laser projection apparatus may determine that the second offset direction is a direction s4 parallel to the pixel column direction and close to the origin of the screen coordinate system, and the laser projection apparatus may control the pixels in the projection image to be shifted by the second target difference value in a direction s3 parallel to the pixel column direction and far from the origin of the screen coordinate system.
And step 408, displaying prompt information.
After detecting that the first target projection position of any one of the feature graphs is located outside the projection screen, the laser projection equipment can display prompt information, wherein the prompt information is used for prompting that the deformation of the projected image is large, so that a user is reminded of adjusting the position of the laser projection equipment or the distortion coefficient of a projection lens in time to adjust the projection position of the projected image. For example, the prompt message may be "the projected image has a large deformation, please adjust the position of the laser projection device".
In the related art, referring to fig. 6 and 7, after the laser projection apparatus is displaced, an angle exists between the projection screen 20 and the projection image 50, and at this time, the projection image 50 is deformed in a trapezoidal shape. Referring to fig. 8, after the projection lens of the laser projection apparatus is largely distorted, the edge of the projected image 50 is deformed.
By adopting the method provided by the embodiment of the disclosure, even if the projection lens of the laser projection equipment is greatly distorted or the laser projection equipment is displaced, the projection image projected and displayed on the projection screen can not be deformed, and the better display effect of the projection image is ensured.
It should be noted that the order of the steps of the correction method for the projected image provided by the embodiment of the present disclosure may be appropriately adjusted, and the steps may also be deleted according to the situation. For example, step 408 may be deleted as appropriate, or steps 405 to 407 may be deleted as appropriate. Any method that can be easily conceived by those skilled in the art within the technical scope of the present disclosure is covered by the protection scope of the present disclosure, and thus, the detailed description thereof is omitted.
In summary, the embodiments of the present disclosure provide a method for correcting a projection image, which can determine a first target projection position of a feature pattern and a second target projection position of a reference point according to a perspective transformation coefficient, a shooting position of the feature pattern, and a shooting position of the reference point in a main screen. Thereafter, the projection position of the projection image may be corrected based on the first target projection positions 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 equipment is distorted or the laser projection equipment is displaced, the projection image projected and displayed on the projection screen cannot be deformed, and the good display effect of the projection image is ensured.
In addition, because the displayed target image comprises the main picture and the playing state of the main picture is kept unchanged, the method provided by the embodiment of the disclosure can ensure continuous playing of the main picture while correcting the projection position of the projected image, thereby ensuring continuous watching of the user and having better user experience.
Referring to fig. 9, 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 determination circuit 15, and a correction circuit 16.
The light source assembly 11 is configured 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, and the optical transmission lens is used for transmitting the laser beam emitted by the laser light source to the optical modulation component 12. The laser light source may be a three-color laser light source, a monochromatic laser light source, or a two-color laser light source, which is not limited in the 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.
The correction circuit 16 is configured to generate a control signal according to a pixel value of the target image in response to the correction instruction, control the light modulation component 12 to modulate the light beam irradiated onto the surface thereof into an image light beam according to the control signal, and transmit the image light beam to the projection lens 13. The projection lens 13 is used for transmitting the image beam to the projection screen 20 so as to project and display the target image on the projection screen 20.
If the camera 40 is connected to the correction circuit 16 and the position determination circuit 14, the correction circuit 16 may send a shooting instruction to the camera 40 after detecting a target duration of the correction instruction, the camera 40 shoots the projection screen 20 after receiving the shooting instruction, and sends the obtained shot image to the position determination circuit 14. The position determination circuit 14 may then perform steps 102-104, and steps 402-406 described above.
After that, the difference determination circuit 15 and the correction circuit 16 execute the above-described step 104 and the above-described step 407. The difference value determination circuit 15 is configured to determine a first difference value, a first shift direction, a second difference value, and a second shift direction, and send the position shift amount to the correction circuit 16. The correction circuit 16 is configured to correct the projection position of the projection image according to the first difference, the first shift direction, the second difference, and the second shift direction.
Referring to fig. 2 and 9, embodiments of the present disclosure provide a laser projection apparatus for:
and in response to the correction instruction, displaying a target image on the projection screen, wherein the target image comprises a main picture and a plurality of characteristic graphs surrounding the main picture, and the color of each characteristic graph is different from the background color of the area except the main picture in the target image.
And acquiring a shot image obtained by shooting the projection screen by the camera.
For each feature pattern, determining a projection position of a first target 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.
And determining the projection position of the reference point on the second target on the projection screen according to the perspective transformation coefficient and the shooting position of the reference point in the main picture in the shot image.
And correcting the projection position of the projection image according to the first target projection positions of the plurality of feature patterns and the second target projection position of the reference point.
In summary, the embodiment of the present disclosure provides a laser projection apparatus, which can determine a first target projection position of a feature pattern and a second target projection position of a reference point according to a perspective transformation coefficient, a shooting position of the feature pattern, and a shooting position of the reference point in a main picture. Thereafter, the projection position of the projection image may be corrected based on the first target projection positions 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 equipment is distorted or the laser projection equipment is displaced, the projection image projected and displayed on the projection screen cannot be deformed, and the good display effect of the projection image is ensured.
Alternatively, the reference point is located on a boundary of the main picture, the color of the boundary of the main picture being different from the background color of the region other than the main picture in the target image.
Optionally, the laser projection device is configured to:
and determining a third target projection position of a target vertex of the target image on the projection screen, a boundary of the target image, a boundary of the main picture and a graph formed by the plurality of characteristic graphs which are all quadrangles according to the first target projection position of the target characteristic graph, the second target projection position of the reference point and the target ratio in the plurality of characteristic graphs, wherein the reference point is the vertex of the boundary of the main picture.
And correcting the projection position of the projection 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 target characteristic graph is a characteristic graph of which the distance from the reference point is smaller than a distance threshold value; the target ratio is positively correlated with the difference between the second initial projection position and the first initial projection position, and negatively correlated with the difference between the third initial projection position and the first initial projection position. The target vertex is a vertex closest to the reference point among the plurality of vertices of the target image. The first initial projection position, the second initial projection position and the third initial projection position are respectively projection positions of a target vertex, a target feature graph and a reference point on the projection screen when the projection image is not deformed.
Optionally, the target ratio may include a first ratio and a second ratio; the laser projection device is used for:
and determining the first coordinate of the third target projection position of the target vertex according to the first coordinate of the first target projection position of the target feature graph, the first coordinate of the second target projection position of the reference point and the first ratio.
And determining a second coordinate of a third target projection position of the target vertex according to the second coordinate of the first target projection position of the target feature graph, the second coordinate of the second target projection position of the reference point and the second ratio.
A first target difference value of the first coordinate of the third target projection position and the first coordinate of the first initial projection position is determined, and a first offset direction of the first coordinate of the third target projection position relative to the first coordinate of the first initial projection position is determined.
The pixels in the projected image are controlled to move the first target difference in a direction opposite to the first offset direction.
A second target difference value of the second coordinate of the third target projection position and the second coordinate of the first initial projection position is determined, and a second offset direction of the second coordinate of the third target projection position relative to the second coordinate of the first initial projection position is determined.
The pixels in the projected image are controlled to move by the second target difference in a direction opposite to the second shift direction.
The first ratio is a ratio of a first initial difference value to a second initial difference value, the first initial difference value is a difference value of a first coordinate of a second initial projection position and a first coordinate of a first initial projection position, and the second initial difference value is a difference value of a first coordinate of a third initial projection position and the first coordinate of the first initial projection position. The second ratio is a ratio of a third initial difference value to a fourth initial difference value, the third initial difference value is a difference value between a second coordinate of the second initial projection position and a second coordinate of the first initial projection position, and the fourth initial difference value is a difference value between a second coordinate of the third initial projection position and a second coordinate of the first initial projection position.
Optionally, the laser projection device is further configured to:
and if the first target projection position of each characteristic graph is positioned in the projection screen, determining a 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 picture in the shot image.
Optionally, the laser projection device is further configured to:
and if the first target projection position of any one of the feature graphs is positioned outside the projection screen, displaying prompt information, wherein the prompt information is used for prompting that the deformation of the projection image is larger.
In summary, the embodiment of the present disclosure provides a laser projection apparatus, which can determine a first target projection position of a feature pattern and a second target projection position of a reference point according to a perspective transformation coefficient, a shooting position of the feature pattern, and a shooting position of the reference point in a main picture. Thereafter, the projection position of the projection image may be corrected based on the first target projection positions 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 equipment is distorted or the laser projection equipment is displaced, the projection image projected and displayed on the projection screen cannot be deformed, and the good display effect of the projection image is ensured.
The disclosed embodiment provides a laser projection apparatus, including: a memory, a processor and a computer program stored on the memory, the processor implementing the method for correcting a projected image provided by the above method embodiments when executing the computer program, such as the method shown in fig. 1 or fig. 4.
The disclosed embodiments provide a computer-readable storage medium, in which instructions are stored, and the instructions are loaded and executed by a processor to implement the correction method of the projected image provided by the above method embodiments, such as the method shown in fig. 1 or fig. 4.
Embodiments of the present disclosure provide a computer program product comprising instructions which, when run on a computer, cause the computer to perform a method of correcting a projected image as provided in the above method embodiments, for example the method shown in fig. 1 or fig. 4.
In the disclosed embodiments, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The term "plurality" in the embodiments of the present disclosure means two or more.
The above description is intended to be exemplary only and not to limit the present disclosure, and any modification, equivalent replacement, or improvement made without departing from the spirit and scope of the present disclosure is to be considered as the same as the present disclosure.

Claims (10)

1. A method of correcting a projected image, applied to a laser projection apparatus, the method comprising:
in response to a correction instruction, displaying a target image on a projection screen, wherein the target image comprises a main picture and a plurality of characteristic graphs surrounding the main picture, and the color of each characteristic graph is different from the background color of a region except the main picture in the target image;
acquiring a shot image obtained by shooting the projection screen by a camera;
for each feature pattern, determining a first target projection position of the feature pattern on the projection screen according to a perspective transformation coefficient of the camera and a shooting position of the feature pattern in the shot image;
determining a 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 picture in the shot image;
and correcting the projection position of the projection image according to the first target projection positions of the plurality of characteristic graphs and the second target projection position of the reference point.
2. The method according to claim 1, wherein the reference point is located on a boundary of the main picture, and a color of the boundary of the main picture is different from a background color of a region other than the main picture in the target image.
3. The method according to claim 1, wherein the boundary of the target image, the boundary of the main picture, and the graph composed of the plurality of feature graphs are polygons, and the reference points are vertices of the boundary of the main picture; the correcting the projection position of the projection image according to the first target projection positions of the plurality of feature patterns and the second target projection position of the reference point includes:
determining a third target projection position of a target vertex of the target image on the projection screen according to a first target projection position of a target feature graph in the plurality of feature graphs, a second target projection position of the reference point and a target ratio;
correcting the projection position of the projection 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 target feature graph is a feature graph of which the distance from the reference point is smaller than a distance threshold value; 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 in the multiple vertexes of the target image; the first initial projection position, the second initial projection position and the third initial projection position are respectively projection positions of the target vertex, the target feature graph and the reference point on the projection screen when the projection image is not deformed.
4. The method of claim 3, wherein the target ratio comprises a first ratio and a second ratio; determining a third target projection position of a target vertex of the target image on the projection screen according to a first target projection position of a target feature pattern in the plurality of feature patterns, a second target projection position of the reference point, and a target ratio, including:
determining a first coordinate of a third target projection position of the target vertex according to the first coordinate of the first target projection position of the target feature graph, the first coordinate of the second target projection position of the reference point and a first ratio;
determining a second coordinate of a third target projection position of the target vertex according to a second coordinate of the first target projection position of the target feature graph, a second coordinate of the second target projection position of the reference point and a second ratio;
the correcting the projection position of the projection 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 includes:
determining a first target difference value of the first coordinate of the third target projection position and the first coordinate of the first initial projection position, and a first offset direction of the first coordinate of the third target projection position relative to the first coordinate of the first initial projection position;
controlling pixels in the projected image to move the first target difference in a direction opposite the first offset direction;
determining a second target difference value of the second coordinate of the third target projection position and the second coordinate of the first initial projection position, and a second offset direction of the second coordinate of the third target projection position relative to the second coordinate of the first initial projection position;
controlling pixels in the projected image to move the second target difference in a direction opposite the second offset direction;
the first ratio is a ratio of a first initial difference value and a second initial difference value, the first initial difference value is a difference value of a first coordinate of the second initial projection position and a first coordinate of the first initial projection position, and the second initial difference value is a difference value of a first coordinate of the third initial projection position and a first coordinate of the first initial projection position;
the second ratio is a ratio of the third initial difference to a fourth initial difference, the third initial difference is a difference between the second coordinate of the second initial projection position and the second coordinate of the first initial projection position, and the fourth initial difference is a difference between the second coordinate of the third initial projection position and the second coordinate of the first initial projection position.
5. The method of any of claims 1 to 4, further comprising:
and if the first target projection positions of the plurality of feature patterns are all located in the projection screen, determining a 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 picture in the shot image.
6. The method of claim 5, further comprising:
and if the first target projection position of any one of the feature graphs is positioned outside the projection screen, displaying prompt information, wherein the prompt information is used for prompting that the deformation of the projection image is larger.
7. A laser projection device, wherein the laser projection device is configured to:
in response to a correction instruction, displaying a target image on a projection screen, wherein the target image comprises a main picture and a plurality of characteristic graphs surrounding the main picture, and the color of each characteristic graph is different from the background color of a region except the main picture in the target image;
acquiring a shot image obtained by shooting the projection screen by a camera;
for each feature pattern, determining a first target projection position of the feature pattern on the projection screen according to a perspective transformation coefficient of the camera and a shooting position of the feature pattern in the shot image;
determining a 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 picture in the shot image;
and correcting the projection position of the projection image according to the first target projection positions of the plurality of characteristic graphs and the second target projection position of the reference point.
8. The laser projection apparatus according to claim 7, wherein the reference point is located on a boundary of the main picture, a color of the boundary of the main picture being different from a background color of a region other than the main picture in the target image.
9. The laser projection device of claim 7, wherein the laser projection device is configured to:
determining a third target projection position of a target vertex of the target image on the projection screen, a boundary of the target image, a boundary of the main picture and a picture formed by the plurality of feature pictures are all quadrangles according to a first target projection position of a target feature picture, a second target projection position of the reference point and a target ratio in the plurality of feature pictures, wherein the reference point is a vertex of the boundary of the main picture;
correcting the projection position of the projection 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 target feature graph is a feature graph of which the distance from the reference point is smaller than a distance threshold value; 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 in the multiple vertexes of the target image; the first initial projection position, the second initial projection position and the third initial projection position are respectively projection positions of the target vertex, the target feature graph and the reference point on the projection screen when the projection image is not deformed.
10. The laser projection device of claim 9, wherein the target ratio comprises a first ratio and a second ratio; the laser projection device is configured to:
determining a first coordinate of a third target projection position of the target vertex according to the first coordinate of the first target projection position of the target feature graph, the first coordinate of the second target projection position of the reference point and a first ratio;
determining a second coordinate of a third target projection position of the target vertex according to a second coordinate of the first target projection position of the target feature graph, a second coordinate of the second target projection position of the reference point and a second ratio;
determining a first target difference value of the first coordinate of the third target projection position and the first coordinate of the first initial projection position, and a first offset direction of the first coordinate of the third target projection position relative to the first coordinate of the first initial projection position;
controlling pixels in the projected image to move the first target difference in a direction opposite the first offset direction;
determining a second target difference value of the second coordinate of the third target projection position and the second coordinate of the first initial projection position, and a second offset direction of the second coordinate of the third target projection position relative to the second coordinate of the first initial projection position;
controlling pixels in the projected image to move the second target difference in a direction opposite the second offset direction;
the first ratio is a ratio of a first initial difference value and a second initial difference value, the first initial difference value is a difference value of a first coordinate of the second initial projection position and a first coordinate of the first initial projection position, and the second initial difference value is a difference value of a first coordinate of the third initial projection position and a first coordinate of the first initial projection position;
the second ratio is a ratio of the third initial difference to the fourth initial difference, the third initial difference is a difference between the second coordinate of the second initial projection position and the second coordinate of the first initial projection position, and the fourth initial difference is a difference between the second coordinate of the third initial projection position and the second coordinate of the first initial projection position.
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