Digital image correction method for continuous variable-focal-length optical imaging system

Abstract

The invention discloses a digital image correction method for a continuous variable-focal-length optical imaging system. The digital image correction method comprises the steps of acquiring planar template images which are photographed by an image camera in a plurality of discrete focal lengths, performing off-line calibration on a distortion parameter which corresponds with each focal length of a variable-focal-length lens; performing curve fitting on the distortion parameter which corresponds with each focal length for obtaining a fitting formula or establishing a distortion parameter lookup table; according to the actual operation focal length of the image camera, obtaining a lens distortion parameter which corresponds with the actual operation focal length through the distortion parameter lookup table or calculation by the fitting formula; and constructing a projection conversion relationship from an image camera coordinate system to a map coordinate system according to position gesture data and the lens distortion parameter in imaging of the image camera, and performing resampling on the pixel brightness value after coordinate conversion for obtaining an orthographic projection image after correction on the squint deformation and lens distortion. The digital image correction method realizes a purpose of simultaneous correction for squint trapezoidal distortion and variable-focal-length nonlinear distortion in the variable-focal-length imaging system.

Description

technical field [0001] The invention relates to the field of digital image processing, in particular to a digital image distortion correction method for a continuous zoom optical imaging system. Background technique [0002] The continuous variable focal length optical system has the advantage of not losing the target during the field of view conversion process, can search and capture fast moving targets, and better realize the functions of searching for targets in a large field of view and distinguishing targets in a small field of view. It has been widely used in measurement and measurement. Due to system manufacturing and assembly errors, the nonlinear distortion characteristics of the zoom lens change with the change of the focal length. At the same time, due to the change of the attitude of the aircraft and the orientation of the camera's boresight, the aerial camera shoots and images the ground at a certain oblique angle, resulting in complex geometry. Deformation ser...

AI Technical Summary

Problems solved by technology

[0006] The invention provides a digital image correction method for a continuous zoom optical imaging system to solve the technical problem that the existing image correction method cannot simultaneously correct the nonlinear distortion and squint trapezoidal distortion of the imaging system

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