A NEW METHOD FOR DISTORTION CORRECTION OF ELECTRONIC ENDOSCOPE IMAGES

A new method to correct the barrel distortion of an electronic endoscope image is presented, A correction model assuming circularly symmetric distortion is introduced with the following model parameters: the center of distortion and the coefficients of polynomials representing the distortion correction in the radial direction, If the imaging system is distortion-free, straight lines in the object space should be imaged as straight lines, Based on this criterion, a distorted image of a standard pattern consisting of a grid of several straight lines is recorded, and the model parameters are then estimated as a basis for straightening distorted lines. This method has the advantage of not needing a careful placement of the standard pattern for calibration. Correction results are presented for the grid pattern chart to verify a sufficient degree of correction, Examples of distortion correction of real intestinal images and physicians' comments are also presented.