Restoration of halftoned color-quantized images using projection onto convex sets

Restoration of color-quantized images is rarely addressed in the literature, especially when the images are color-quantized with halftoning. Direct application of existing restoration techniques are generally inadequate to deal with this problem. We propose a POCS-based restoration algorithm to solve the problem. This algorithm derives useful information for restoration with the available color palette and the mechanism of a halftoning process. It is shown to be able to provide a good restoration result.