Adaptive halftone scheme to preserve image smoothness and sharpness with region identification

摘要

An adaptive halftone scheme is applied to a compound document to smooth the rendering while preserving edge sharpness. The adaptive halftone scheme involves identifying document regions as either smooth, edge or texture. Each identified region is then processed as follows. Wherever a smooth region is adjacent to an edge region and wherever a smooth region is adjacent to a texture region, create a transition region in a portion of that smooth region bordering that other region and apply a blend of a screening halftone technique (SCN) and an error diffusion with screening halftone technique (EDSCN) to that transition region, apply SCN to the remainder of that smooth region, apply ED to that other region if it is an edge region, and apply either EDSCN or SCN if it is texture region. <IMAGE> <IMAGE> <IMAGE> <IMAGE>