A NEW METHOD FOR DISTORTION CORRECTION OF ELECTRONIC ENDOSCOPE IMAGES

A new method to correct the barrel distortion of an electronic endosco pe image is presented, A correction model assuming circularly symmetri c distortion is introduced with the following model parameters: the ce nter of distortion and the coefficients of polynomials representing th e distortion correction in the radial direction, If the imaging system is distortion-free, straight lines in the object space should be imag ed as straight lines, Based on this criterion, a distorted image of a standard pattern consisting of a grid of several straight lines is rec orded, and the model parameters are then estimated as a basis for stra ightening distorted lines. This method has the advantage of not needin g a careful placement of the standard pattern for calibration. Correct ion results are presented for the grid pattern chart to verify a suffi cient degree of correction, Examples of distortion correction of real intestinal images and physicians' comments are also presented.