CN109816734B - Camera calibration method based on target spectrum - Google Patents
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- CN109816734B CN109816734B CN201910063329.5A CN201910063329A CN109816734B CN 109816734 B CN109816734 B CN 109816734B CN 201910063329 A CN201910063329 A CN 201910063329A CN 109816734 B CN109816734 B CN 109816734B
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Abstract
The invention discloses a camera calibration method based on a target spectrum, which comprises the following steps: selecting a correction light source, and determining a camera and a lens of an optical system; 2) adjusting a lens of the optical system to a virtual focus state; 3) under the condition of ensuring that the focal plane of the lens is parallel to the correction light source, moving the correction light source to approach the optical system until the correction light source can completely cover the orientation field of view in a virtual focus state; 4) adjusting the exposure time of the camera to ensure that the central brightness does not exceed 80% of the saturation of the camera and the edge brightness is not lower than 30% of the saturation of the camera; 5) the obtained image is stored as a dark corner picture, and a dark field curved surface correction model is obtained; 6) and under the target light source, performing matrix operation on the shot picture and the dark field curved surface correction model, and performing reverse reduction on each point of the obtained picture according to the attenuation of the dark field curved surface correction model relative to the central mean value to obtain a calibrated picture. The method can solve the problem of uneven brightness of the light source end caused by the property of the light-emitting panel.
Description
Technical Field
The invention relates to the technical field of liquid crystal panel detection, in particular to a camera calibration method based on a target spectrum.
Background
In the industrial application field, the part related to optical detection usually has optical distortion at the lens end due to the influence of the optical system itself, and usually, we use a uniform light source, such as an integrating sphere, to correct the brightness unevenness generated by the optical system by means of FFC (flat field correction). The FFC correction refers to a bright field correction main step of camera flat field correction, a uniform light-emitting object can be shot by using software carried by a camera, the response capability of different pixel points on the correction camera to a light source becomes consistent, so that the camera can feed back the consistent response effect to the uniform light source, however, the method is limited in the memory space of the camera, FFC data under the colors of a few channels can be usually stored, and meanwhile, the uniform light source is high in cost and difficult to carry, so that the method is only suitable for being carried out when the camera leaves a factory.
The optical system usually comprises a camera and a lens, and if the lens is replaced, the original FFC correction is also failed, so that the flexible adaptability of the optical equipment is greatly limited, and the equipment upgrading cost in the aspect of optical detection is high and the maintenance is difficult.
Because in the optical detection equipment use, display panel light source luminance receives the angle influence, even optical equipment has already passed through FFC and has corrected the process, when shooing even luminescent panel, still can observe the uneven phenomenon of camera original image luminance that obtains, directly use this original image to carry out data processing, cause equipment such as AOI equipment and Demura to appear erroneous judgement easily, increase technical cost.
Disclosure of Invention
Based on the technical problems in the background art, the invention provides a camera calibration method based on a target spectrum, which is realized by a software method, is more flexible and lower in cost, and can effectively solve the problem of uneven light source end brightness acquisition caused by the property of a light-emitting panel.
In order to achieve the above object, the present invention provides a method for calibrating a camera based on a target spectrum, which is characterized in that the method comprises the following steps:
1) selecting a correction light source, determining a camera and a lens of an optical system, adjusting the physical setting condition of the optical system to a use state, and placing the correction light source in the working range of the optical system;
2) adjusting a lens of the optical system to a virtual focus state;
3) under the condition of ensuring that the focal plane of the lens is parallel to the correction light source, moving the correction light source to approach the optical system until the correction light source can completely cover the orientation field of view in a virtual focus state;
4) adjusting the exposure time of the camera to ensure that the central brightness does not exceed 80% of the saturation of the camera and the edge brightness is not lower than 30% of the saturation of the camera;
5) the acquired image is stored as a dark corner picture, and a dark field curved surface correction model is obtained according to the dark corner picture;
6) and under a target light source, performing matrix operation on the picture shot by the camera in the normal use process and the dark field curved surface correction model, and performing reverse reduction on each point of the obtained image according to the attenuation of the dark field curved surface correction model relative to the central mean value to obtain a calibrated picture.
Preferably, the method for obtaining the dark field curved surface correction model according to the dark angle picture in the step 5) is to fit the dark angle picture by using a Spline tool in a Matlab software platform, and remove noise to obtain the fitted dark field curved surface correction model.
Preferably, the dark field curved surface correction model comprises a common dark field curved surface correction model, a dark field curved surface correction model based on brightness, and a dark field curved surface correction model based on color, and the dark field curved surface correction model based on brightness comprises a high brightness correction model, a middle brightness correction model, and a low brightness correction model.
Preferably, the target light source is identical to the wavelength of the light of the correction light source. Preferably, the target light source and the correction light source are both display panels which are subjected to OTP and GAMMA correction.
Preferably, the corrective light source meets the requirement of area array uniformity. Optimally, the correcting light source is a uniform panel after the Demura repair is carried out.
Preferably, a white lens cover with diffuse reflection characteristics is used in the step 1), and the correction light source is placed below the lens cover, so that the area array uniformity of the correction light source is improved.
The invention has the advantages that:
1) the method can effectively solve the problem of uneven brightness acquisition of the light source end caused by the property of the light-emitting panel, can replace an FFC to a certain extent for use, and can also be used as a supplement means after the FFC is corrected to obtain higher-quality camera picture data;
2) compared with the conventional FFC correction and under the condition of not using the correction, the method has the advantages that the acquired data has better repeatability and reliability, and the data distortion caused by different incident angles relative to the camera placing position can be better avoided. 3) The present invention is more flexible and less costly than conventional FFC corrections.
Drawings
Fig. 1 is a schematic view of a dark field surface correction model.
Fig. 2 shows a standard deviation view of a spherical surface in a state where no correction method is used.
Fig. 3 shows a standard deviation view of a spherical surface in a state where the FFC correction method is used.
Fig. 4 is a spherical standard deviation view in a state of a camera calibration method using a target light source.
Detailed Description
The invention is described in further detail below with reference to the following figures and examples, which should not be construed as limiting the invention.
The invention provides a camera calibration method based on a target spectrum, which comprises the following steps:
1) selecting a correction light source, determining a camera and a lens of an optical system, adjusting the physical setting condition of the optical system to a use state, and placing the correction light source in the working range of the optical system;
2) adjusting a lens of the optical system to a virtual focus state;
3) under the condition of ensuring that the focal plane of the lens is parallel to the correction light source, moving the correction light source to approach the optical system until the correction light source can completely cover the orientation field of view in a virtual focus state;
4) adjusting the exposure time of the camera to ensure that the central brightness does not exceed 80% of the saturation of the camera and the edge brightness is not less than 30% of the saturation of the camera so as to ensure the image quality, and shooting the image for storage after no error is confirmed;
5) the acquired image is stored as a dark corner picture, and the image is applied to a subsequent algorithm and used as dark field correction of the camera picture. For the obtained dark corner picture, noise is removed by adopting fitting modes such as a Spline tool in a Matlab software platform, and a fitted dark field curved surface correction model is obtained, as shown in FIG. 1; the dark field curved surface correction model comprises a common dark field curved surface correction model, a dark field curved surface correction model based on brightness and a dark field curved surface correction model based on color;
6) and under a target light source, performing matrix operation on the picture shot by the camera in the normal use process and the dark field curved surface correction model, and performing reverse reduction on each point of the obtained image according to the attenuation of the dark field curved surface correction model relative to the central mean value to obtain a calibrated picture. And then in the actual use process, performing matrix operation on the image shot by each optical system and the dark field curved surface, and reversely restoring the obtained image to obtain the corrected camera shot image.
The method can be applied to obtaining and correcting the dark field curved surface correction model in different colors and brightness degrees according to actual needs, the steps are consistent with those of the method, and only corresponding conditions need to be matched and matched. For example, for a high-brightness light source \ a medium-brightness light source \ a low-brightness shooting dark angle picture, a high-brightness correction model, a medium-brightness correction model and a low-brightness correction model are obtained. And shooting vignetting pictures of green, red, blue and other pictures to obtain a green correction model, a red correction model and a blue correction model.
Similarly, the method can be carried out by directly using FFC correction of a camera without using the calculation of a vignetting model, and only a reliable and uniform target correction light source is needed to be used.
The invention has better flexible adaptability to the correction light source which meets the following requirements, and can be very conveniently updated in a large amount and in time:
(1) the correction light source needs to have similarity with the target light source, mainly in terms of light emitting material and color, such as but not limited to, the same type of OTP and Gamma corrected display panel.
(2) The correcting light source needs to be a uniform panel with good area array uniformity, such as a uniform panel after Demura restoration, other uniform light-emitting panels, a notebook computer screen or a mobile phone screen with good quality, and the like.
(3) The white lens cover with diffuse reflection characteristics is used, and the correction light source is placed below the lens cover, so that the area array uniformity of the correction light source can be improved.
And (3) verification experiment:
(1) the method comprises the following steps of (1) shooting the same light source (an OLED light emitting panel is used for carrying out experiments, and a certain screen flash exists in the OLED light emitting panel) for multiple times respectively at the center and the edge of a view field without using a correction method, and using the same optical system and an evaluation method, so as to obtain the difference of data, wherein the calculation method comprises the following steps: the smaller the spherical standard deviation std2 (evaluation data acquired at the center of the field-evaluation data acquired at the edge of the field), the better the repeatability. Std2 ═ 0.0611 in the state where no correction method was used, as shown in fig. 2.
(2) After the conventional FFC correction method is used, the same optical system and the same evaluation method are applied, the same light-emitting source is shot for multiple times and is respectively located at the center and the edge of the field of view, and the difference of data is obtained, and std2 is 0.0394 in the state of using the FFC correction method, as shown in fig. 3.
(3) After the correction method based on the target light source is used, the same optical system and the same evaluation method are applied, the same light emitting source is shot for multiple times and is respectively located at the center and the edge of the field of view, the difference of data is obtained, and std2 in the state of the camera calibration method using the target light source is 0.0306, as shown in fig. 4.
The experimental result shows that the target light source correction-based method can improve the quality and stability of the target image acquired by the corresponding optical system more pertinently and provide a more accurate and reliable data source.
Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and those skilled in the art can make various changes and modifications within the spirit and scope of the present invention without departing from the spirit and scope of the appended claims.
Claims (8)
1. A camera calibration method based on target spectrum is characterized in that: the method comprises the following steps:
1) selecting a correction light source, determining a camera and a lens of an optical system, adjusting the physical setting condition of the optical system to a use state, and placing the correction light source in the working range of the optical system;
2) adjusting a lens of the optical system to a virtual focus state;
3) under the condition of ensuring that the focal plane of the lens is parallel to the correction light source, moving the correction light source to approach the optical system until the correction light source can completely cover the orientation field of view in a virtual focus state;
4) adjusting the exposure time of the camera to ensure that the central brightness does not exceed 80% of the saturation of the camera and the edge brightness is not lower than 30% of the saturation of the camera;
5) the acquired image is stored as a dark corner image, and a dark field curved surface correction model is obtained according to the dark corner image;
6) under a target light source, performing matrix operation on an image shot by the camera in the normal use process and the dark field curved surface correction model, and performing reverse reduction on each point of the obtained image according to the attenuation of the dark field curved surface correction model relative to the central mean value to obtain a calibrated image.
2. The target-spectrum-based camera calibration method as claimed in claim 1, wherein: and 5) fitting the vignetting image by using a Spline tool in a Matlab software platform, removing noise, and obtaining a fitted dark field curved surface correction model according to the vignetting image.
3. The target-spectrum-based camera calibration method as claimed in claim 1, wherein: the dark field curved surface correction model comprises a common dark field curved surface correction model, a brightness-based dark field curved surface correction model and a color-based dark field curved surface correction model, and the brightness-based dark field curved surface correction model comprises a high brightness correction model, a medium brightness correction model and a low brightness correction model.
4. The target-spectrum-based camera calibration method as claimed in claim 1, wherein: the wavelength of the light waves of the target light source and the wavelength of the light waves of the correction light source are consistent.
5. The target-spectrum-based camera calibration method as claimed in claim 4, wherein: the target light source and the correction light source are both display panels which are subjected to OTP and GAMMA correction.
6. The target-spectrum-based camera calibration method as claimed in claim 1, wherein: the correcting light source meets the requirement of area array uniformity.
7. The target-spectrum-based camera calibration method as claimed in claim 6, wherein: the correcting light source is a uniform panel after the Demura repair is carried out.
8. The target-spectrum-based camera calibration method as claimed in claim 1, wherein: in the step 1), a white lens cover with diffuse reflection characteristics is used, and a correction light source is placed below the lens cover.
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| CN112033542B (en) * | 2020-11-06 | 2021-01-29 | 武汉精测电子集团股份有限公司 | Brightness and chrominance measuring method, device and equipment and readable storage medium |
| CN113194251B (en) * | 2021-04-28 | 2022-05-27 | 烟台艾睿光电科技有限公司 | Method, device, equipment and medium for correcting infrared thermal imaging equipment |
| CN115426458B (en) * | 2022-11-01 | 2023-04-07 | 荣耀终端有限公司 | Light source detection method and related equipment thereof |
| CN115988342B (en) * | 2023-03-20 | 2023-07-07 | 中国空气动力研究与发展中心计算空气动力研究所 | Flow display image shooting device, method, system and medium |
Family Cites Families (20)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101804521B (en) * | 2010-04-15 | 2014-08-20 | 中国电子科技集团公司第四十五研究所 | Galvanometer system correction device and correction method thereof |
| JP2014233038A (en) * | 2013-05-30 | 2014-12-11 | パナソニック株式会社 | Camera apparatus and imaging method |
| CN103578088B (en) * | 2013-11-20 | 2017-01-04 | 中国人民解放军海军大连舰艇学院 | A kind of starry sky image processing method |
| CN103730477B (en) * | 2013-12-31 | 2019-07-19 | 上海集成电路研发中心有限公司 | Image sensor pixel array and forming method thereof based on dark angle compensation |
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| CN104581098B (en) * | 2014-12-01 | 2016-09-28 | 北京思比科微电子技术股份有限公司 | A kind of adaptive processing method of lens shading |
| CN105744262A (en) * | 2014-12-12 | 2016-07-06 | 致茂电子(苏州)有限公司 | Detection system capable of correcting light source, and light source correction method thereof |
| CN104574269B (en) * | 2015-01-08 | 2017-07-28 | 中国科学院国家天文台 | A kind of antidote of base astronomical telescope observed image line direction towing in month |
| CN105574833B (en) * | 2015-12-23 | 2018-11-27 | 上海奕瑞光电子科技股份有限公司 | It trembles in detector darkfield image template or taps the identification and bearing calibration of artifact |
| CN105681680A (en) * | 2016-02-22 | 2016-06-15 | 信利光电股份有限公司 | Image vignetting correction method, device and system |
| CN105959511B (en) * | 2016-05-18 | 2019-02-05 | 珠海市杰理科技股份有限公司 | Camera lens shadow correction method and system |
| CN105933686B (en) * | 2016-05-19 | 2017-10-10 | 浙江大学 | A kind of colored camera lens shadow correction method of the adaptive digital camera of light source |
| CN106204498B (en) * | 2016-07-22 | 2020-03-31 | 上海联影医疗科技有限公司 | Image correction method and device |
| CN106206637B (en) * | 2016-08-23 | 2019-07-16 | 上海奕瑞光电子科技股份有限公司 | A kind of radioscopic image sensor and the method for correcting image interference |
| CN107454349A (en) * | 2017-09-29 | 2017-12-08 | 天津工业大学 | It is a kind of based on the steady noise self-adapting detecting of sCMOS cameras and bearing calibration |
| CN108088845B (en) * | 2017-12-07 | 2020-09-11 | 武汉精测电子集团股份有限公司 | Imaging correction method and device based on weak information retention |
| CN108335664B (en) * | 2018-01-19 | 2019-11-05 | 长春希达电子技术有限公司 | The method that camera image curved surface is demarcated using two-dimentional relative movement mode |
| CN108198220B (en) * | 2018-01-19 | 2021-09-21 | 长春希达电子技术有限公司 | Accurate calibration method for image curved surface of optical camera |
| CN108305294B (en) * | 2018-01-19 | 2021-06-15 | 长春希达电子技术有限公司 | Accurate calibration method for camera image curved surface with grid target |
| CN108918559B (en) * | 2018-07-28 | 2021-08-17 | 北京纳米维景科技有限公司 | X-ray image detector for realizing image self-correction and method thereof |
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