An iterative context dependent color halftoning algorithm is presentedin this paper. Unlike the normal approach of halftoning a color image, in whichthe color separations of the original image are halftoned independently, the originalcolor image is halftoned in a context dependent manner. The method is basedon a monochromatic halftoning method that was presented earlier. The number ofdots to be placed in each color separation of the final halftone image or in differentparts of it is decided in advance. There is no dot in the initial halftoned image.In each iteration a new dot is placed at some particular position. The position ofthis dot depends on where the previous dots were placed. The final halftonedimage is obtained after the predetermined numbers of dots have been placed inthe color separations of the halftoned image. The strategy to reduce color noiseand gain control over color gamut is to prevent dot-on-dot printing as much aspossible. The color shifts that might occur because of this dot-off-dot printingstrategy have to be compensated before halftoning. This transformation is dependenton some data for the printer with which the halftoned color image is supposedto be printed. The experiments verify that the color noise is notably smallerin the images that are halftoned by the proposed method compared to the imageshalftoned using the normal approach of halftoning color images.
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