Restoration of half-toned color-quantized images using particle swarm optimization with wavelet mutation

Restoration of color-quantized images is rarely addressed in the literature, especially when the images are color-quantized with halftoning. Most existing restoration algorithms are generally inadequate to deal with this problem as they were proposed for restoring noisy blurred images. In this paper, a restoration algorithm based on Particle Swarm Optimization with wavelet mutation (WPSO) is proposed to solve the problem. This algorithm makes a good use of the available color palette and the mechanism of a halftoning process to derive useful a priori information for restoration. Simulation results show that it can improve the quality of a half-toned color-quantized image remarkably in terms of both SNRI and convergence rate. The subjective quality of the restored images can also be improved.