Method and system for calibrating distortion coefficient of zoom lens

Abstract

The invention discloses a method for calibrating a distortion coefficient of a zoom lens, and the method comprises the following steps: collecting a group of mark plate zoom images which are shot by a current video camera in a zooming manner from the shortest focus, and identifying at least four angular points of a mark plate in the various zoom images; getting parameters of the video camera for the image I0 at the shortest focus under a zoom value f0, wherein the parameters of the video camera comprise a zoom parameter and the distortion coefficient; on the basis of taking the parameters of the video camera under the zoom value f0 as initial values, calculating the parameters of the video camera for the other zoom images in the group under the corresponding zoom values respectively by successive iteration; and generating a distortion coefficient curve according to the distortion coefficients of the group of the zoom images. By adopting the method, the distortion coefficient of the zoom lens can be simply and fast calibrated, and the distortion coefficient of the zoom lens during long focal length can be especially ensured.

Description

technical field [0001] The invention relates to the technical field of camera calibration, in particular to a method for calibrating a distortion coefficient of a zoom lens and a system for calibrating a distortion coefficient of a zoom lens. Background technique [0002] Generally speaking, lens distortion (lens distortion) is actually a general term for the inherent perspective distortion of optical lenses, that is, the distortion caused by perspective. This distortion is very detrimental to the imaging quality of photos. After all, the purpose of photography is to Reproduction, not exaggeration, but because this is an inherent characteristic of the lens (convex lens converges light, concave lens diverges light), it cannot be eliminated, but can only be improved. Currently, the highest quality lenses are tested under extremely strict conditions, and the edges of the lens will also produce varying degrees of distortion and distortion. [0003] In the production of TV progr...

AI Technical Summary

Problems solved by technology

However, in actual use, the camera usually needs to zoom. Since the lens is mostly composed of lens groups, not only the internal parameters of the lens will change, but also the distortion coefficient will change with the focal length of the lens.

If you use Zhang Zhengyou’s calibration method to calibrate the distortion coefficient for each zoom value, it will obviously be very complicated and cumbersome. In addition, because the image is enlarged at a long focal length, the general calibration board will not be fully visible. If you place it far away It will be blurred again, so Zhang Zhengyou’s calibration method is also difficult to achieve for long focal lengths

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