Computationally fast techniques to reduce AWGN and speckle in videos

Abstract

Fast schemes to reduce additive white Gaussian noise (AWGN) and speckle in videos are presented. The proposed schemes use a change detection technique to measure the interframe motion and carry out estimations in both the spatial and temporal directions of the video. In the case of AWGN reduction, the well-known edge adaptive Wiener filter is used to perform the spatial estimation. Two different filters to carry out temporal estimation are presented based on novel weighted scalar Kalman and weighted running average filters, respectively. These temporal estimators are applied on the spatial estimate to obtain the spatiotemporal estimate. A new method is then used to appropriately combine the spatial and spatiotemporal estimates in order to obtain the final estimate of the uncorrupted signal. To achieve speckle reduction, we use an unbiased homomorphic system that comprises an edge adaptive filter for spatial estimation and the weighted running average filter for temporal estimation. The effectiveness of the various proposed algorithms is demonstrated and compared with that of some of the existing schemes through extensive simulations. It is found that the use of a change detection technique, instead of the popularly used complex motion estimation and compensation technique, to measure the interframe motion results in a considerable reduction of processing time. The proposed schemes perform equally well or better than the existing schemes in reducing the noise in videos.