HALF-TONE TO CONTINUOUS-TONE CONVERSION OF ERROR-DIFFUSION CODED IMAGES

We consider the problem of reconstructing a continuous-tone (contone) image from its halftoned version, where the halftoning process is done by error diffusion. We present an iterative nonlinear decoding algori thm for halftone-to-contone conversion and show simulation results tha t compare the performance of the algorithm to that of conventional lin ear low-pass filtering. We find that the new technique results in subj ectively superior reconstruction. As there is a natural relationship b etween error diffusion and Sigma Delta modulation, our reconstruction algorithm can also be applied to the decoding problem for Sigma Delta modulators.