Abstract

A method of reconstructing a continuous tone image of greyscale values that have been converted to a halftone image of black and white spots. The conversion to the digital halftone image spots was by comparing each pixel of the continuous tone greyscale image to a periodic screen pattern and providing either a black or white spot based on the comparison. In particular, to reconstruct the continuous tone greyscale image from the halftone image, each spot of the halftone image is isolated along with a neighborhood of surrounding spots. For each neighborhood, the maximum screen pattern value producing a white spot is compared to the minimum screen value producing a black spot. If the minimum screen value giving a black spot is greater than the maximum screen value giving a white spot, then the greyscale pixel value of the isolated spot is the average of the maximum and minimum screen values. If the minimum screen value giving a black spot is less than the maximum screen value giving a white spot, then the process is repeated after deleting that portion of the neighborhood of surrounding spots containing the maximum or minimum screen value furthest from the isolated spot.