A spatially adaptive gradient-projection algorithm to remove blocking artifacts of H.264 video coding standard

Abstract

In this paper, we present a spatially adaptive gradient-projection algorithm for H.264 video coding standard to remove blocking artifacts using local statistics. The proposed approach is based on the regularized iterative techniques. In order to complement the weak points of the Constraint Least Squares (CLS) method, we combine the projection method with the CLS method. In order to adaptively process each pixel according to the Human Visual System (HVS), the modified local variance is defined when the CLS method is applied. What's more, the location-based laplacian operators are proposed to efficiently remove the blocking artifacts between the blocks. And the difference of vertically or horizontally adjoining pixels is utilized to constrain the solution space when the projection method is applied. Quantization Index (QP) in H.264 is also used to control the degree of smoothness. The simulation results show that the proposed post-processing filter works better than the loop filter in H.264 with preserving the edges information at once. copyright © 2008 IEICE.