Research On Post-processing Techniques Based On HEVC Video Coding Standard

Video coding standard has gone through several generations, such asJPEG,MPEG,AVS video coding standard and so on, and gradually formed a moremature standard H.264/AVC to be the representative of video coding standard. Inrecent years, the H.264/AVC standard is no longer able to meet people’s needs, soVCEG and MPEG standards organizations cooperate and set up the organizationcalled JCT-VC (Joint Collaborative Team on Video Coding) for providing adevelopment platform for the new generation video coding standard HEVC (HighEfficiency Video Coding).The HEVC follows H.264/AVC’s hybrid coding frameworkand the general ideas, and the part of post-processing technology still have madechanges. Post-processing is in the process of coding loop, including deblocking filterand sample adaptive offset. To optimizing the artifacts in reconstruction images, postprocessing technique efficiently reduce the compression distortion caused byprediction and quantization. As the construction images which used as referencepicture is closer to original images, further reducing the cumulative of imagedistortion. This paper is concentrate on the post-processing technology of HEVC, putforward two kinds of method of weighted arithmetic. This method efficientlyimproves the subjective quality of images. The main contributions include thefollowing two aspects:1. The weighted algorithm is proposed based on deblocking filter. Because ofthe flexible block structure of HEVC, the decision of deblocking filter is usuallybased on reconstruction images itself. So that only the correlation between its ownblock is taken into account. Weighted algorithm is proposed in this paper consideredthe correlation between the reconstruction images and original images. Theapplication of weighted coefficients corresponding to the reconstructed imagedeblocking filter which impacts on reducing the difference between reconstructedimages and the original images. To a certain extent, our proposal efficiently improvesthe subjective quality of image compression.2. Put forward the idea of weighted sample adaptive offset. Sample adaptiveoffset is also based on the flexible block structure of HEVC to reduce the distortionbetween reconstruction images and original images. According to the diffenrencebetween the characteristics of each block, offset is chosen diffenrently. Due to avariety of class types, we proposed a method of weakening the filter strength of theedge in the blocks. The main idea is to lower the filter strength in the boundary, inorder to achieve the purpose of reducing the blocking artifact. To a certain extent, ourproposal efficiently improves the subjective quality of images.