Photometric calibration method based on polynomial camera response function and vignetting effect compensation

A camera response and calibration method technology, applied in the field of image processing, can solve the problem that the iterative conditions are not good for the algorithm convergence effect, and achieve the effect of complete and stable photometric calibration and real and natural imaging.

Inactive Publication Date: 2020-02-21
TIANJIN UNIVERSITY OF TECHNOLOGY
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Problems solved by technology

However, its iteration condition is not good for algorithm convergence

Method used

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  • Photometric calibration method based on polynomial camera response function and vignetting effect compensation
  • Photometric calibration method based on polynomial camera response function and vignetting effect compensation
  • Photometric calibration method based on polynomial camera response function and vignetting effect compensation

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Embodiment

[0110] The specific implementation process of camera response function optimization, such as figure 1 Shown:

[0111] 1. In the same scene, use the same camera to change the exposure parameters to shoot 8-10 images as the experimental group, and the number of images is set to Q;

[0112] 2. Determine whether the image is a grayscale image, if not, convert it to a grayscale image;

[0113] 3. Arrange and save the image in order from dark to bright, and obtain the gray value data G(x, y) of each pixel on the image (can be generated directly), x, y are the positions of the pixels, that is, Obtain the third-order array data with the length and width of image pixels as the first and second order, and the image serial number as the second-order dimension;

[0114] 4. Record the exposure value information of each image, and divide them sequentially to obtain Q-1 exposure ratio information The first-order array data obtained for the first time is used as the initial exposure ratio...

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Abstract

The invention discloses a photometric calibration method based on a polynomial camera response function and vignetting effect compensation. The method comprises the following steps: collecting Q images with different exposures in the same scene, arranging the Q images from small to large according to the exposures, sequentially obtaining the primarily corrected exposure ratio Rq1 of the adjacent images, obtaining a primarily corrected exposure ratio matrix, and obtaining the primarily corrected brightness error epsilon 1 of the images; obtaining a primary correction coefficient according to the derivative of the brightness error of the primary correction of the image to the primary correction coefficient; obtaining an exposure ratio matrix of the second correction according to the initialcorrection coefficient, and obtaining a brightness error epsilon2 of the second correction of the image; obtaining a second correction coefficient according to the derivative of the brightness error of the second correction of the image to the second correction coefficient; performing circulating in sequence until epsilon k + 1 is greater than or equal to epsilon k, and outputting a kth correctioncoefficient; and obtaining a luminosity calibration function of the camera image after obtaining a camera image response function. Therefore, luminosity calibration is more complete and stable, and imaging is more real and natural.

Description

technical field [0001] The present invention relates to the technical field of image processing, and more specifically, the present invention relates to a photometric calibration method based on polynomial camera response function and vignetting effect compensation. Background technique [0002] Photometric calibration will show greater advantages with the development of visual technology, and will have great practical value in image modeling and rendering, image stitching, and image processing. It is difficult for ordinary imaging systems to reflect the brightness relationship between the real scene and the image due to illumination changes, and the vignetting effect caused by the influence of the optical lens makes the relationship more complicated. [0003] S.Mann and R.W.Picard proposed a camera response function calibration algorithm based on cross histograms in 1995, making standard provisions for camera response functions. The camera response function calibration alg...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T7/80G06T5/00
CPCG06T7/80G06T5/006
Inventor 周海波张好鑫程纪晟刘振忠孙国庆王桂莲
Owner TIANJIN UNIVERSITY OF TECHNOLOGY
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