Comparison of Efficiency of Various Orthogonal Transforms for Motion-Compensated Interframe Prediction Error Signals

Abstract

A hybrid coding method is one of the most promising methods in realizing low bit rate transmission of motion pictures. However, the efficiency of orthogonal transforms for motion-compensated interframe prediction error signals (abbreviated as MC error signals) has not yet been documented well. In this paper, we investigate the characteristic of MC error signals and compare the efficiency of KLT (Karhunen-Loeve Transform) to that of other transforms (DCT, SLT, HCT, WHT, HAT, and DST) from the viewpoint of entropy, mean square errors, and decorrelation ratio. First, the efficiency of the above-mentioned transforms is compared for intraframe image signals. Second, we calculate the basic functions of KLT for MC error signals and compare the efficiency with that of other transfors. Experimental results show that DCT approximates the efficiency of KLT well for MC error signals. Finally, we apply these orthogonal trasfoms to the hybrid coding method, and show that the DCT give the highest coding performance among these transforms.