Color halftone document segmentation and descreening

The advent of electronic publishing creates strong interest in converting existing printed documents into electronic formats. During this process, image reproduction problems can occur due to the formation of moire patterns in the screened halftone areas. A wavelet packet based color halftone segmentation algorithm is first designed to locate possible halftone regions based on a decision function. A color halftone descreening technique based on the color sigma filter is proposed which does not assume any a priori knowledge about the halftoning process, making it applicable to any color halftone image. Combined with color halftone segmentation techniques, a complete document processing algorithm for color documents is proposed. Experimental results are offered to illustrate the performance of our algorithm.