AVS Intra Mode Decision Algorithm Combined with GSIM
Chang Jua · Journal of Taiyuan University of Technology · 2014
The rate distortion optimization for AVS intra mode decision uses the sum absolute difference(SAD)as the distortion metric.The method is simple,but is not consistent with human vision system(HVS)quite well.The structural similarity(SSIM)proposed recently accords with HVS much more well,but it has some deficiencies in assessing badly blurred images.The model of gradient-magnitude-based structure similarity(GSIM)can solve the problem.The rate distortion optimization using GSIM can be consistent with HVS quite well,but it is complex and not conducive to real-time coding.The paper uses the combination of SAD and GSIM as the distortion metric,calculates the difference of optimal value and suboptimal value for SAD,compare the difference value with the threshold value to determine whether the calculation of GSIM is needed,in where the threshold is adaptive-adjusted based on the intra mode correlation.If GSIM value needs to be calculated,the GSIM optimal values and suboptimal values determine whether correction for intra mode is needed.Experimental results show that the subjective quality of the proposed algorithm is better than that of traditional algorithms,with little increase in encoding time.