Bit Allocation based on Visual Saliency in HEVC

Abstract

As one of the important part in the HEVC reference software, R-lambda model adopts mean absolute difference (MAD) for the coding unit tree (CTU) level bit allocation. However, this optimum method may neglect some important characteristics of human visual system (HVS). In this paper, we propose a novel bit allocation algorithm to process some salient visual information priority. Firstly, an improved video saliency detection algorithm is proposed, which induces temporal correlation into a 2D visual attention model. Secondly, the visual saliency based CTU level bit allocation algorithm is presented by allocating bits for CTUs with their saliency weights. What’s more, with considerations of the temporal quality consistence among Saliency Areas (SAs), a window based weight smoothing model is proposed to achieve better subjective quality. Finally, several experiments are performed on the HEVC reference software, HM16.9, under the low delay P configuration, and the experimental results show that the average BD-Rate of the entire test sequences and of the SAs reduce 1.7% and 6.2%, respectively. The proposed algorithm can also improve subjective quality remarkably.