Trapezoidal correction methods, systems and related equipment for projected images

Abstract

This invention discloses a method, system, and related equipment for trapezoidal correction of projected images. The trapezoidal correction method is applied to a projection device equipped with a distance sensor and includes the following steps: acquiring the distances from the projection device to at least three different distance points on the projection surface; calculating, based on the distances from the projection device to the at least three distance points, the rotation angle of the projected image relative to a plane perpendicular to the projection surface using a preset calculation method; and performing image transformation processing on the projected image based on the rotation angle to achieve trapezoidal correction. The trapezoidal correction method for projected images in this invention can significantly reduce the cost of projection devices and expand their applicability, making them suitable for a wider range of development platforms.

Description

Technical Field

[0001] This invention relates to the field of projection technology, and in particular to a method, system and related equipment for trapezoidal correction of projected images. Background Technology

[0002] A projection device is a device that projects images onto a wall in an enlarged form. It mainly includes a converging projection lens. Commonly used projection devices include movie projectors, slide projectors, and image enlargers.

[0003] The images projected by projection equipment often exhibit trapezoidal distortion because the optical axis is not perpendicular to the wall.

[0004] To correct trapezoidal distortion in images projected by projection devices, the relevant technologies first capture the amount of distortion in the image using a camera, and then use the powerful computing capabilities of a processor (CPU) to provide feedback control to the output image of the projection device, thereby correcting the image and restoring it to a rectangular shape.

[0005] The aforementioned method for correcting trapezoidal distortion in images projected by projection devices requires a powerful processor to work in conjunction with the distortion of images captured by a camera. However, the high cost of cameras leads to high costs for projection devices, and the need for a processor with powerful computing capabilities also limits the applicability of projection devices. Summary of the Invention

[0006] The purpose of this invention is to provide a method, system, and related equipment for trapezoidal correction of projected images that has low production costs and is applicable to a wide range of development platforms.

[0007] To address the aforementioned technical problems, in a first aspect, the present invention provides a trapezoidal correction method for projected images, applied to a projection device equipped with a distance sensor. The trapezoidal correction method for projected images includes the following steps:

[0008] The distances from the projection device to the projection surface are obtained at least three different distance points; wherein the distances of the at least three distance points are respectively measured by the distance sensor, and the at least three distance points are spaced apart and located within the field of view of the distance sensor;

[0009] Based on the distances from the projection device to at least three distance points, the rotation angle of the projected image of the projection device relative to the plane perpendicular to the projection surface is calculated according to a preset calculation method.

[0010] The projected image is transformed according to the rotation angle to achieve trapezoidal correction of the projected image.

[0011] Preferably, there are three distance points: a first distance point, a second distance point, and a third distance point; the preset calculation method for calculating the rotation angle satisfies the following formula:

[0012] ;

[0013] Wherein, θ is the rotation angle; d0 is the distance from the projection device to the first distance point; d1 is the distance from the projection device to the second distance point; d2 is the distance from the projection device to the third distance point; and F is the field of view angle of the distance sensor.

[0014] Preferably, the rotation angle is calculated by the logic operation unit of the projection device.

[0015] Preferably, the image change processing is achieved through adjustment by the image processing unit of the projection device.

[0016] Preferably, the distance sensor is any one of an ultrasonic sensor, an infrared sensor, or a time-of-flight ranging sensor.

[0017] Secondly, the present invention provides a keystone correction system for a projection device, applicable to a projection device equipped with a distance sensor, the keystone correction system comprising:

[0018] An acquisition module is used to acquire the distances from the projection device to at least three different distance points on the projection surface; wherein the distances of the at least three distance points are respectively measured by the distance sensor, and the at least three distance points are spaced apart and located within the field of view of the distance sensor;

[0019] The calculation module is used to calculate the rotation angle of the projected image of the projection device relative to the plane perpendicular to the projection surface, based on the distance from the projection device to at least three distance points and according to a preset calculation method.

[0020] An adjustment module is used to perform image transformation processing on the projected image according to the rotation angle, so as to achieve trapezoidal correction of the projected image.

[0021] Thirdly, the present invention provides a computer device including a memory, a processor, and a computer program stored in the memory that can run on the processor, wherein the processor executes the computer program to implement the trapezoidal correction method for projected images as described above.

[0022] Fourthly, the present invention provides a computer-readable storage medium storing a computer program that, when executed, implements the trapezoidal correction method for projected images as described above.

[0023] Fifthly, the present invention provides a projection device, comprising a distance sensor for measuring the distance from the projection device to at least three different distance points on the projection surface, a logic operation unit for calculating the rotation angle of the projected image of the projection device relative to a plane perpendicular to the projection surface, an image processing unit for performing image transformation processing on the projected image, and an optical imaging system for generating the projected image.

[0024] Compared with related technologies, the trapezoidal correction method for projected images in this invention first measures the distances from the projection device to at least three different distance points on the projection surface using a distance sensor of the projection device; then, based on the distances from the projection device to the at least three distance points, it calculates the rotation angle of the projected image relative to the plane perpendicular to the projection surface using a preset calculation method; finally, it directly performs image transformation processing on the projected image based on the rotation angle to achieve trapezoidal correction. This correction method only requires adding a distance sensor to obtain the distances from the projection device to the projection surface at least three different distance points, and then obtaining the rotation angle through simple calculation to achieve trapezoidal correction of the projected image. The cost of the distance sensor is lower than that of the camera, and the correction can be achieved without using a processor with powerful computing capabilities, thereby greatly reducing the cost of the projection device and expanding its applicability, which is equivalent to making it applicable to a wider range of development platforms. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0026] Figure 1 A schematic flowchart illustrating the steps of a trapezoidal correction method for a projected image provided in an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram illustrating the range of a projected image projected onto a projection surface, provided by an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram of the angle and distance point of a projection device projecting onto the front of the projector, provided in an embodiment of the present invention.

[0029] Figure 4 A schematic diagram illustrating the working principle of a trapezoidal correction method for projected images provided in an embodiment of the present invention;

[0030] Figure 5This is a schematic diagram of the framework of a trapezoidal correction system for a projection device provided in an embodiment of the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] This invention provides a method for trapezoidal correction of projected images, combined with... Figure 1 and Figure 2 As shown, this method is applied to a projection device 100, which is equipped with a distance sensor 101. The trapezoidal correction method for the projected image includes the following steps:

[0034] The structure of the projection device 100 in this embodiment is the same as or similar to that of the projection device 100 described in Embodiment 5 below.

[0035] S1. Obtain the distances from the projection device to at least three different distance points on the projection surface.

[0036] The distances of at least three distance points are respectively measured by the distance sensor 101, and the at least three distance points are spaced apart and located within the field of view (FoV) range of the distance sensor 101; in addition, the field of view range of the distance sensor 101 is also located within the range of the projection surface onto which the projection device 100 projects.

[0037] Meanwhile, the projection surface can be a wall or a flat screen.

[0038] In this embodiment, the distance points include three: a first distance point, a second distance point, and a third distance point, which correspond to the distances between the projection device 100 and the projection surface at three different distance points. Of course, more distance points can be obtained according to actual needs. Preferably, the three distance points are arranged coaxially.

[0039] S2. Based on the distances from the projection device to at least three distance points, calculate the rotation angle of the projected image of the projection device relative to the plane perpendicular to the projection surface using a preset calculation method.

[0040] The rotation angle is calculated by the logic operation unit 102 of the projection device 100.

[0041] In this embodiment, the preset calculation method for calculating the rotation angle satisfies the following formula:

[0042] ;

[0043] Wherein, θ is the rotation angle; d0 is the distance from the projection device to the first distance point; d1 is the distance from the projection device to the second distance point; d2 is the distance from the projection device to the third distance point; and F is the field of view of the distance sensor.

[0044] In addition, the preset calculation formula is obtained based on the following two trigonometric functions; the formula for the first trigonometric function is as follows:

[0045] ;

[0046] The formulas for the second trigonometric function are as follows:

[0047] .

[0048] Combination Figure 3 As shown, the specific derivation process is as follows:

[0049] Given ∠AOC = F (field angle), ∠AOB = F / 2 = ∠BOC = α, the distance from OA = d0, the distance from OB = d1, and the distance from OC = d2; find ∠HOB = θ (rotation angle):

[0050] The distance of OH = d0 cos(θ-α)=d0(cosθcosα+sinθsinα)(1);

[0051] OH=d2 cos(θ+α)=d0(cosθcosα-sinθsinα)(2);

[0052] Let OH = y;

[0053] It can be seen from formula (1): y / d0= cosθcosα+sinθsinα (3);

[0054] It can be seen from formula (2): y / d2= cosθcosα-sinθsinα (4);

[0055] Formula (2) + Formula (4) is: y / d0 + y / d2 = 2cosθcosα, from which we can derive: cosθ = y / 2cosα (1 / d0+1 / d2)(5);

[0056] Formulas (3) and (4) are: y / d0 - y / d2 = 2sinθsinα, from which we can derive: sinθ = y / 2sinα (1 / d0-1 / d2)(6);

[0057] Formula (5) 2 +Formula (6) 2 =1, that is, cos 2 θ+sin 2 θ=1, from which the following formula is derived: (y / 2cosα) (1 / d0+1 / d2)) 2 +(y / 2sinα (1 / d0-1 / d2)) 2 =1; Further derivation yields the following formula: y=((2d0d2) cosαsinα) 2 / (d0+d2) 2 -4d0d2cos 2 α))^;

[0058] Where cosθ=y / d1, the following formula is derived from this:

[0059] θ=cos -1 ((2d0d2) cosαsinα) 2 / (d0d1+d2d1) 2 -4d0d2d1cos 2 α))^;

[0060] α = F / 2, from which the following pre-defined calculation formula can be derived:

[0061] ;

[0062] S3. Perform image transformation processing on the projected image according to the rotation angle to achieve trapezoidal correction of the projected image.

[0063] The image transformation processing is adjusted by the image processing unit 103 of the projection device 100.

[0064] Combination Figure 4As shown, the working principle of the trapezoidal correction method for the projected image in this embodiment is as follows: The distance sensor 101 is activated to acquire the distances from the projection device 100 to three different distance points on the projection surface, and it is determined whether these distance points are qualified, such as whether these distance points are within the field of view of the distance sensor 101, or whether these distance points are within the range projected onto the projection surface by the projection device 100, etc. If qualified, proceed to the next step; The rotation angle is calculated by reverse calculation using the aforementioned preset calculation formula, and it is determined whether the rotation angle is qualified, such as whether the rotation angle is less than 90°, or whether the rotation angle is greater than 0°, if qualified, proceed to the next step; The rotation angle is applied to the image processing unit 103 for image transformation processing, and after completion, proceed to the next step; The projected image is projected onto the projection surface through the optical imaging system 104.

[0065] Compared with related technologies, the trapezoidal correction method for projected images in this invention first measures the distances from the projection device 100 to at least three different distance points on the projection surface using the distance sensor 101 of the projection device 100; then, based on the distances from the projection device 100 to the at least three distance points, the rotation angle of the projected image of the projection device 100 relative to the plane perpendicular to the projection surface is calculated according to a preset calculation method; finally, the image transformation processing is performed directly on the projected image based on the rotation angle to achieve trapezoidal correction of the projected image. This correction method only requires adding a distance sensor 101 to obtain the distances from the projection device 100 to at least three different distance points on the projection surface, and then obtaining the rotation angle through simple calculation to achieve trapezoidal correction of the projected image. The cost of the distance sensor 101 is lower than that of a camera, and correction can be achieved without the use of a processor with powerful computing capabilities, thereby greatly reducing the cost of the projection device 100 and expanding its applicability, which is equivalent to making its applicable development platform more extensive. In addition, using the distance sensor 101 eliminates the need for back-and-forth control adjustments, and its response time is faster than that of the back-and-forth control adjustment method. Furthermore, while using a camera for shooting can only be adjusted under specific conditions, using the distance sensor 101 allows adjustment under any condition.

[0066] Example 2

[0067] This invention provides a keystone correction system 200 for a projection device, combined with... Figure 5 As shown, it includes:

[0068] The acquisition module 201 is used to acquire the distances from the projection device to at least three different distance points on the projection surface; wherein the distances of the at least three distance points are respectively measured by the distance sensor, and the at least three distance points are spaced apart and located within the field of view of the distance sensor;

[0069] The calculation module 202 is used to calculate the rotation angle of the projected image of the projection device relative to the plane perpendicular to the projection surface according to a preset calculation method based on the distance from the projection device to at least three distance points.

[0070] The adjustment module 203 is used to perform image transformation processing on the projected image according to the rotation angle, so as to realize the trapezoidal correction of the projected image.

[0071] Since the trapezoidal correction system of the projection device in this embodiment corresponds to the trapezoidal correction method of the projected image in the first embodiment above, it can also achieve the technical effect achieved by the trapezoidal correction method of the projected image in the first embodiment above, and will not be elaborated here.

[0072] Example 3

[0073] This invention provides a computer device including a memory, a processor, and a computer program stored in the memory that can run on the processor. When the processor executes the computer program, it implements the trapezoidal correction method for projected images as described in Embodiment 1 above.

[0074] Since the computer device in this embodiment can implement the trapezoidal correction method for projected images in Embodiment 1, it can also achieve the technical effect achieved by the trapezoidal correction method for projected images in Embodiment 1, which will not be elaborated here.

[0075] Example 4

[0076] This invention provides a computer-readable storage medium storing a computer program that, when executed, implements the trapezoidal correction method for projected images described in Embodiment 1 above.

[0077] Since the computer-readable storage medium in this embodiment can implement the trapezoidal correction method for projected images in Embodiment 1, it can also achieve the technical effect achieved by the trapezoidal correction method for projected images in Embodiment 1, and will not be elaborated here.

[0078] Example 5

[0079] This invention provides a projection device 100, which includes a distance sensor 101 for measuring the distance from the projection device 100 to at least three different distance points on the projection surface, a logic operation unit 102 for calculating the rotation angle of the projected image of the projection device 100 relative to a plane perpendicular to the projection surface, an image processing unit 103 for performing image transformation processing on the projected image, and an optical imaging system 104 for generating the projected image.

[0080] In this embodiment, the projection device 100 is used to implement the trapezoidal correction method for the projected image in the first embodiment described above.

[0081] Since the projection device 100 in this embodiment can implement the trapezoidal correction method for the projected image in the first embodiment above, it can also achieve the technical effect achieved by the trapezoidal correction method for the projected image in the first embodiment above, which will not be elaborated here.

[0082] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for trapezoidal correction of projected images, applied to a projection device, characterized in that, The projection device is equipped with a distance sensor, and the trapezoidal correction method for the projected image includes the following steps: The distances from the projection device to the projection surface are obtained at least three different distance points; wherein the distances of the at least three distance points are respectively measured by the distance sensor, and the at least three distance points are spaced apart and located within the field of view of the distance sensor; Based on the distances from the projection device to at least three distance points, the rotation angle of the projected image of the projection device relative to a plane perpendicular to the projection surface is calculated according to a preset calculation method; the three distance points are: a first distance point, a second distance point, and a third distance point; the preset calculation method for calculating the rotation angle satisfies the following formula: ； Wherein, θ is the rotation angle; d0 is the distance from the projection device to the first distance point; d1 is the distance from the projection device to the second distance point; d2 is the distance from the projection device to the third distance point; F is the field of view angle of the distance sensor, the angle formed by the line connecting the projection device to the first distance point and the line connecting the projection device to the third distance point is the field of view angle, and the line connecting the projection device to the second distance point is the angle bisector of the field of view angle; acos is the inverse cosine function; The projected image is transformed according to the rotation angle to achieve trapezoidal correction of the projected image.

2. The trapezoidal correction method for projected images as described in claim 1, characterized in that, The rotation angle is calculated by the logic operation unit of the projection device.

3. The trapezoidal correction method for projected images as described in claim 1, characterized in that, The image change processing is achieved through adjustment by the image processing unit of the projection device.

4. The trapezoidal correction method for projected images as described in claim 1, characterized in that, The distance sensor can be any one of an ultrasonic sensor, an infrared sensor, or a time-of-flight distance sensor.

5. A keystone correction system for a projection device, used in a projection device, characterized in that, The projection device is equipped with a distance sensor, and the keystone correction system of the projection device includes: An acquisition module is used to acquire the distances from the projection device to at least three different distance points on the projection surface; wherein the distances of the at least three distance points are respectively measured by the distance sensor, and the at least three distance points are spaced apart and located within the field of view of the distance sensor; The calculation module is used to calculate, based on the distances from the projection device to at least three distance points, the rotation angle of the projected image of the projection device relative to a plane perpendicular to the projection surface, according to a preset calculation method; the three distance points are: a first distance point, a second distance point, and a third distance point; the preset calculation method for calculating the rotation angle satisfies the following formula: ； Wherein, θ is the rotation angle; d0 is the distance from the projection device to the first distance point; d1 is the distance from the projection device to the second distance point; d2 is the distance from the projection device to the third distance point; F is the field of view angle of the distance sensor, the angle formed by the line connecting the projection device to the first distance point and the line connecting the projection device to the third distance point is the field of view angle, and the line connecting the projection device to the second distance point is the angle bisector of the field of view angle; acos is the inverse cosine function; An adjustment module is used to perform image transformation processing on the projected image according to the rotation angle, so as to achieve trapezoidal correction of the projected image.

6. A computer device, characterized in that, The computer device includes a memory, a processor, and a computer program stored in the memory that can run on the processor. When the processor executes the computer program, it implements the trapezoidal correction method for the projected image as described in any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed, implements the trapezoidal correction method for projected images as described in any one of claims 1 to 4.

Images