A robust nonlinear filtering approach to inverse halftoning

A new blind inverse halftoning algorithm based on a nonlinear filtering technique of low computational complexity and low memory requirement is proposed in this research. It is called blind since we do not require the knowledge of the halftone kernel. The proposed scheme performs nonlinear filtering in conjunction with edge enhancement to improve the quality of an inverse halftoned image. Distinct features of the proposed approach include efficiently smoothing halftone patterns in large homogeneous areas, additional edge enhancement capability to recover the edge quality, and an excellent PSNR performance with only local integer operations and a small memory buffer. (C) 2001 Academic Press.