Fast image restoration in large digital photos

In this paper, a new technique for acceleration of iterative image restoration algorithms is presented. Unlike other fast algorithms which tend to accelerate the rate of convergence of iterative procedures, the proposed method achieves the speed improvement by extending the equivalent restoration filter of a small local block to the whole image directly. Considerable reduction in restoration time can be achieved with little image distortion. The speedup achieved increases rapidly with the drop of the ratio of the block size to the whole image size. An expression for estimating the acceleration factor is derived and confirmed experimentally. The proposed method has a special application in restoration of very large digital images with the prevalence of digital cameras.