Blind restoration of images degraded by space-variant blurs using iterative algorithms for both blur identification and image restoration

This paper addresses the problem of digital blind restoration of images degraded by space-variant blurs and noise. The existing Expectation-Maximization (EM) algorithm reported in the literature is extended in this paper and combined with the region adaptive technique to handle the problem of identifying spatially variant blurs. The proposed algorithm is a two-step interative process. The expectation step of the EM algorithm is modified by the use of iterative image restoration. The entire image is divided into disjointed regions and the blur is identified in these regions using the proposed modified form of the EM algorithm. The iterative Constrained Least Squares (CLS) algorithm used in space-invariant image restoration is extended to restore the space variant blur images. Spatially adaptive algorithms for restoration are also applied. Experiments have been carried out to evaluate the performances of the proposed algorithms.