Research on the Algorithm of Adaptive Loop Filter Based on Flexible Quadtree

The algorithm of adaptive loop filter based on flexible quad tree (Q-ALF) is put forward targeting the problem that deblocking loop filter used by H.264/AVC cant further improve video coding quality. This algorithm, through the original image and the image after deblocking filter, works out wiener filter and selects a wiener filter with optimal size by taking the SAD of the image after Wiener filtering and the original image as RDO cost and based on RDO model, then uses this filter to filtrate the area that needs filtration. Simulation result shows that Q-ALF algorithm can improve the PSNR of the reconstructed image and decrease bit rate; meanwhile, Q-ALF algorithm can better eliminate blocking effect, improving the subjective performance of the reconstructed image.