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

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