Perceptually motivated fast coding unit size decision for HEVC intracoding based on visual regularity

Abstract

Although the flexible quad-tree structure in high efficiency video coding (HEVC) has achieved significant performance improvement over H.264/AVC, it remarkably increases computation complexity due to the search for the optimal coding unit (CU) size in a very large space. We propose perceptually motivated fast CU decision for HEVC intracoding based on visual regularity. Since visual regularity represents visual masking effect in the human visual system (HVS) on structure information, i.e., irregularity concealment effect, we use it for early CU termination. We predict irregular CUs by exploiting the information of neighboring CUs, which would not introduce too much distortion. Also, the distortion cannot be perceived by HVS due to the visual masking effect in irregular regions. The experimental results demonstrate that the proposed method saves 24% computational cost on average as compared to anchor with only 0.52% increase in Bjontegaard delta bit rate and 0.02 dB loss in Bjontegaard delta PSNR.