Patent ID: 6215911
Filing Date: 2001-04-10
Classification: G01R,G06T

Abstract:
A method for correcting an original image composed of a plurality of pixels in rows and columns which is produced with an image acquisition method having a sensitivity characteristic which varies over the image in a non-uniform slowly changing manner, said method comprising the steps of:(a) analyzing said original image in at least one direction for changes in pixel intensity from pixel to pixel by comparing, for each pixel in said original image, an intensity of a pixel under analysis with an intensity of an adjacent pixel and, for any pixel under analysis which has an intensity which is greater, by more than a predetermined value, than an intensity of the adjacent pixel, replacing the intensity of said pixel under analysis with an intensity value formed from the intensity of the adjacent pixel and the predetermined value, and thereby obtaining an auxiliary image;(b) low-pass filtering said auxiliary image to obtain a low-pass filtered auxiliary image having an intensity distribution associated therewith.(c) from said intensity distribution of said low-pass filtered auxiliary image, assigning sensitivity values respectively to the pixels of said low-pass filtered auxiliary image; and(d) weighting the intensities of the respective pixels in said original image with a value which is a reciprocal of the assigned sensitivity value for a corresponding pixel in said lowpass filtered auxiliary image, and thereby obtaining a corrected image.