IMAGE PROCESSING METHOD FOR THE REMOVAL OF SPOT DEFECTS AND APPARATUS THEREFOR

摘要

PCT No. PCT/GB87/00404 Sec. 371 Date Mar. 15, 1988 Sec. 102(e) Date Mar. 15, 1988 PCT Filed Jun. 11, 1987 PCT Pub. No. WO87/07741 PCT Pub. Date Dec. 17, 1987.A method for processing an image for the removal of spot defects comprising scanning and sampling the image to generate any array of pixel image values and constructing a corresponding array of pixel image values for the processed image by carrying out the following steps: (a) examining the image values of each pixel of a predetermined subset of pixels in a block surrounding a central pixel thereby determining the image value corresponding to the highest and lowest values in said predetermined subset of said block (Ahigh and Alow respectively), (b) determining the image value corresponding to the central pixel of said block (Acenter), (c) calculating either the ratio: R1=(Alow-Acenter)/(Ahigh-Alow) or the ratio R2=(Acenter-Ahigh)/(Ahigh-Alow), (d) if the ratio is positive and its value is above a predetermined threshold value, writing an average value calculated on image values in the block to the element of the processed image array corresponding to said central pixel or, if not, writing the existing value (Acenter ) to said element, and (e) repeating steps (a) to (d) until every pixel has been processed as the central pixel.