CN112288649A - Image correction method and device for cylindrical object perspective imaging distortion - Google Patents
Image correction method and device for cylindrical object perspective imaging distortion Download PDFInfo
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- 238000003384 imaging method Methods 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 title claims abstract description 26
- 238000003702 image correction Methods 0.000 title claims abstract description 22
- 238000004590 computer program Methods 0.000 claims description 13
- 238000012937 correction Methods 0.000 claims description 5
- 238000000605 extraction Methods 0.000 claims description 4
- 238000001514 detection method Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 238000005259 measurement Methods 0.000 description 5
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2207/00—Indexing scheme for image analysis or image enhancement
- G06T2207/10—Image acquisition modality
- G06T2207/10004—Still image; Photographic image
Abstract
An image correction method and device for cylindrical object perspective imaging distortion are provided, wherein the image correction method comprises the following steps: step one, finding out edge lines on two sides of a cylindrical object, and independently extracting image areas of the cylindrical object; secondly, establishing a coordinate system for the cylindrical object image area according to a height central line and a width central line of the original image; thirdly, obtaining the angle of the shot cylindrical object according to the shooting focal length of the camera and the positive direction width of the cylindrical object image area, and then obtaining the distance from the center of the cylindrical object to the focus by combining the radius of the cylindrical object; and corresponding each point on the perspective distorted image of the cylindrical object to each point on the corrected image, thereby correcting the perspective distorted image. The invention also provides an image correction system for perspective imaging distortion of the cylindrical object, a terminal device and a computer readable storage medium. The invention can measure the shape, texture or damage size of the cylindrical curved surface more accurately.
Description
Technical Field
The invention belongs to the field of image processing, and relates to an image correction method and device for perspective imaging distortion of a cylindrical object.
Background
In 2010, researchers at Tianjin science and technology university propose a three-dimensional object surface texture reconstruction method based on a cylindrical back projection algorithm, the method only equates the shooting condition of a cylindrical object to a telecentric lens imaging model, and the model only occupies a small proportion in practical problems and is not applicable to a large number of pinhole imaging models in engineering. Currently, the detection technology based on image processing becomes the research direction of a large number of scientific researchers, and a plurality of new technologies and new devices appear. When the surface of the cylindrical object is detected, a simple and effective method is not available, the deformation of the image of the cylindrical object can be corrected according to the actual surface texture, and then the perspective imaging distortion image is directly processed in the detection process, so that the detection result has larger error with the actual condition. Based on the above situation, it is necessary to provide a correction method for correcting the distorted cylindrical image.
Disclosure of Invention
The present invention aims to solve the problem of the prior art that no distorted image is corrected during the surface detection of the cylindrical object, and provides a method and a device for correcting the distorted image of the perspective imaging of the cylindrical object, which can avoid the occurrence of a large error in the detection result and enable the measurement of the shape, texture or damage size of the cylindrical curved surface to be more accurate.
In order to achieve the purpose, the invention has the following technical scheme:
an image correction method for cylindrical object perspective imaging distortion comprises the following steps:
step one, finding out edge lines on two sides of a cylindrical object, and independently extracting image areas of the cylindrical object;
secondly, establishing a coordinate system for the cylindrical object image area according to a height central line and a width central line of the original image;
thirdly, obtaining the angle of the shot cylindrical object according to the shooting focal length of the camera and the positive direction width of the cylindrical object image area, and then obtaining the distance from the center of the cylindrical object to the focus by combining the radius of the cylindrical object; and corresponding each point on the perspective distorted image of the cylindrical object to each point on the corrected image, thereby correcting the perspective distorted image.
As a preferable mode of the image correction method according to the present invention, in the second step, a y-axis of a coordinate system is established according to a height center line of the original image, and an x-axis of the coordinate system is established according to a width center line.
As a preferable embodiment of the image correction method of the present invention, in the third step, the focal length of the image taken by the camera is known as f, the radius of the cylindrical object is known as r, the positive image width x0 of the cylindrical object region is known, and the angle α of the cylindrical object and the distance z from the center of the cylindrical object to the focal point are obtained by the following equation:
α＝π-arctan(x0/f)
z＝r/cosα
any point (x) on the cylindrical object image1,y1) And the corresponding point (x) on the image after correction thereof2,y2) The relationship is as follows:
and corresponding each point on the cylindrical object perspective distortion image to each point on the corrected image according to the formula, so that the perspective distortion image is corrected.
The invention also provides an image correction system for perspective imaging distortion of a cylindrical object, which comprises:
the cylindrical object image area extraction module is used for finding out the sidelines on the two sides of the cylindrical object and independently extracting the cylindrical object image area;
the coordinate system establishing module is used for establishing a coordinate system for the cylindrical object image area according to the height central line and the width central line of the original image;
the image correction module is used for solving the angle of the shot cylindrical object according to the shooting focal length of the camera and the positive direction width of the cylindrical object image area, and solving the distance from the center of the cylindrical object to the focal point by combining the radius of the cylindrical object; and corresponding each point on the cylindrical object perspective distortion image to each point on the corrected image, so that the perspective distortion image is corrected.
The invention also provides a terminal device, which comprises a memory, a processor and a computer program stored in the memory and capable of running on the processor, wherein the processor realizes the steps of the image correction method for the perspective imaging distortion of the cylindrical object when executing the computer program.
The present invention also provides a computer-readable storage medium storing a computer program which, when executed by a processor, implements the steps of the image correction method for distortion of perspective imaging of a cylindrical object.
Compared with the prior art, the invention has the following beneficial effects: through analyzing the image characteristics of the current pinhole model imaging and the geometric dimension relation of the cylindrical object image, the cylindrical image has larger distortion to the display of the surface texture of the actual cylindrical object, especially when the surface damage is detected, the identification error of the surface image is easy to occur, and if the surface is not expanded according to the actual condition, the detection result has large error. The invention is equivalent to unfolding the cylindrical curved surface into a plane for imaging, so that perspective distortion images are corrected, the adverse effect of the 'near-large-far-small' phenomenon in perspective imaging on a measurement result is eliminated, and the measurement of the shape, texture or damage size of the cylindrical curved surface is more accurate.
Drawings
FIG. 1 is a schematic diagram of a distorted image of a cylindrical object in perspective imaging according to an embodiment 1 of the present invention;
FIG. 2 is a schematic diagram of the present invention for extracting cylindrical object image regions separately;
FIG. 3 is a schematic diagram of a coordinate system established according to a height center line and a width center line of an original image;
FIG. 4 is a schematic diagram of an image distorted by perspective imaging of a cylindrical object according to embodiment 2 of the present invention;
FIG. 5 is a schematic diagram of an image after correction in embodiment 2 of the present invention.
Detailed Description
Referring to fig. 1-3, the method for correcting distorted images of perspective imaging of cylindrical objects according to the present invention comprises the following steps:
step one, finding out edge lines on two sides of a cylindrical object, and independently extracting image areas of the cylindrical object;
establishing a coordinate system for the cylindrical object image area according to a height central line and a width central line of the original image, establishing a y axis of the coordinate system according to the height central line of the original image, and establishing an x axis of the coordinate system according to the width central line;
thirdly, obtaining the angle of the shot cylindrical object according to the shooting focal length of the camera and the positive direction width of the cylindrical object image area, and then obtaining the distance from the center of the cylindrical object to the focus by combining the radius of the cylindrical object; and corresponding each point on the perspective distorted image of the cylindrical object to each point on the corrected image, thereby correcting the perspective distorted image.
Knowing the focal length of the camera and the radius of the cylindrical object as f, the positive image width x0 of the cylindrical object area is known, and the angle α of the cylindrical object and the distance z from the center of the cylindrical object to the focal point are obtained by the following equation:
α＝π-arctan(x0/f)
z＝r/cosα
any point (x) on the cylindrical object image1,y1) And the corresponding point (x) on the image after correction thereof2,y2) The relationship is as follows:
and corresponding each point on the cylindrical object perspective distortion image to each point on the corrected image according to the formula.
Referring to fig. 4 and 5, the image correction method for cylindrical object perspective imaging distortion is equivalent to unfolding a cylindrical curved surface into a plane for imaging, so that a perspective distortion image is corrected, the adverse effect of the 'near-large-far-small' phenomenon in perspective imaging on a measurement result is eliminated, and the measurement of the shape, texture or damage size of the cylindrical curved surface is more accurate.
The invention also provides an image correction system for perspective imaging distortion of a cylindrical object, which comprises:
the cylindrical object image area extraction module is used for finding out the sidelines on the two sides of the cylindrical object and independently extracting the cylindrical object image area;
the coordinate system establishing module is used for establishing a coordinate system for the cylindrical object image area according to the height central line and the width central line of the original image;
the image correction module is used for solving the angle of the shot cylindrical object according to the shooting focal length of the camera and the positive direction width of the cylindrical object image area, and solving the distance from the center of the cylindrical object to the focal point by combining the radius of the cylindrical object; and corresponding each point on the cylindrical object perspective distortion image to each point on the corrected image, so that the perspective distortion image is corrected.
The invention also provides a terminal device, which comprises a memory, a processor and a computer program stored in the memory and capable of running on the processor, wherein the processor realizes the steps of the image correction method for the perspective imaging distortion of the cylindrical object when executing the computer program.
The present invention also provides a computer-readable storage medium storing a computer program which, when executed by a processor, implements the steps of the image correction method for distortion of perspective imaging of a cylindrical object.
The computer program may be divided into one or more modules/units, which are stored in the memory and executed by the processor to perform the method of the invention.
The terminal device can be a desktop computer, a notebook, a palm computer, a cloud server and other computing devices, and can also be a processor and a memory. The processor may be a Central Processing Unit (CPU), other general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, etc. The memory may be used to store the computer programs and/or modules, and the processor may implement various functions of feature extraction for multiple focus sequence images by running or executing the computer programs and/or modules stored in the memory and invoking data stored in the memory.
The above description is only one specific example of the present invention and should not be construed as limiting the invention in any way. It will be apparent to persons skilled in the art that various modifications and variations in form and detail can be made therein without departing from the spirit and principles of the invention, and these modifications and variations will fall within the scope of the invention as defined by the appended claims.
Claims (6)
1. An image correction method for cylindrical object perspective imaging distortion is characterized by comprising the following steps:
step one, finding out edge lines on two sides of a cylindrical object, and independently extracting image areas of the cylindrical object;
secondly, establishing a coordinate system for the cylindrical object image area according to a height central line and a width central line of the original image;
thirdly, obtaining the angle of the shot cylindrical object according to the shooting focal length of the camera and the positive direction width of the cylindrical object image area, and then obtaining the distance from the center of the cylindrical object to the focus by combining the radius of the cylindrical object; and corresponding each point on the perspective distorted image of the cylindrical object to each point on the corrected image, thereby correcting the perspective distorted image.
2. The method for correcting distorted image of cylindrical object perspective imaging according to claim 1, wherein: and step two, establishing a y axis of a coordinate system according to a height central line of the original image, and establishing an x axis of the coordinate system according to a width central line.
3. The method of claim 1, wherein the focal length of the camera is f, the radius of the cylindrical object is r, the positive direction width x0 of the image of the cylindrical object area is known, and the angle α of the cylindrical object, the distance z between the center of the cylindrical object and the focal point are obtained by the following formula:
α＝π-arctan(x0/f)
z＝r/cosα
any point (x) on the cylindrical object image1,y1) And the corresponding point (x) on the image after correction thereof2,y2) The relationship is as follows:
and corresponding each point on the cylindrical object perspective distortion image to each point on the corrected image according to the formula, so that the perspective distortion image is corrected.
4. An image correction system for distortion of fluoroscopic imaging of a cylindrical object, comprising:
the cylindrical object image area extraction module is used for finding out the sidelines on the two sides of the cylindrical object and independently extracting the cylindrical object image area;
the coordinate system establishing module is used for establishing a coordinate system for the cylindrical object image area according to the height central line and the width central line of the original image;
the image correction module is used for solving the angle of the shot cylindrical object according to the shooting focal length of the camera and the positive direction width of the cylindrical object image area, and solving the distance from the center of the cylindrical object to the focal point by combining the radius of the cylindrical object; and corresponding each point on the cylindrical object perspective distortion image to each point on the corrected image, so that the perspective distortion image is corrected.
5. A terminal device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: the processor, when executing the computer program, implements the steps of the method for correcting distorted images of perspective imaging of cylindrical objects according to any one of claims 1 to 3.
6. A computer-readable storage medium storing a computer program, characterized in that: the computer program when executed by a processor implements the steps of the method for image correction of distortion in fluoroscopic imaging of a cylindrical object as claimed in any one of claims 1 to 3.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112446823A (en) * | 2021-02-01 | 2021-03-05 | 武汉中科通达高新技术股份有限公司 | Monitoring image display method and device |
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| CN110738608A (en) * | 2019-05-27 | 2020-01-31 | 首都师范大学 | plane image correction method and system |
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| JP2000331151A (en) * | 1999-05-25 | 2000-11-30 | Nec Corp | Image processing method, image distortion correction processor and storage medium recording program of the processor |
| WO2019049421A1 (en) * | 2017-09-08 | 2019-03-14 | 株式会社ソニー・インタラクティブエンタテインメント | Calibration device, calibration system, and calibration method |
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