Halftone dot-growth technique based on morphological filtering

摘要

A method for converting an original halftone bitmap image to a color converted halftone bitmap image by morphological filtering of the original image to compensate for tone and color reproduction characteristics comprising: providing an original halftone bitmap image. The method includes providing a set of asymmetrical morphological filters that have the property that when they are applied recursively in order, the features in the halftone bitmap image are dilated or eroded by varying amounts by extending or reducing the edges first in one direction, then in two directions, etc. The method further includes segmenting the original halftone bitmap image into blocks and for each block: applying the set of morphological filters to the original halftone bitmap image to produce a set of modified halftone bitmap images; estimating the percent dot area of the original halftone bitmap image and the set of modified halftone bitmap images; applying a predetermined dot-gain to the percent dot area of the original halftone bitmap image to produce a modified percent dot area; selecting the modified halftone bitmap image whose percent dot area is closest to the modified percent dot area to produce a block of the color corrected halftone bitmap image; replacing the original halftone bitmap image with the combined blocks of selected modified halftone bitmap image.