Perceptual adaptive Lagrangian multiplier for high efficiency video coding

In high efficiency video coding (HEVC), Lagrangian rate distortion optimization (RDO) technique is used to optimize the rate distortion (RD) performance. However, the corresponding Lagrangian multiplier does not consider the perceptual characteristic of the input video and thus is not effective for perceptual video coding. To address this problem, an efficient perceptual adaptive Lagrangian multiplier for HEVC is proposed. Based on the human visual system (HVS) observation that the region with less perceptual sensitivity can tolerate more distortion, the Lagrangian multiplier is adaptively adjusted for each coding tree unit (CTU) based on its perceptual sensitivity so that the perceptual quality of the reconstructed video can be improved. The above-mentioned perceptual sensitivity for each CTU is measured according to two perceptual features-spatial energy ratio and temporal motion activity. Experimental results have shown that the proposed method is able to significantly improve the perceptual RD performance, compared with the original HEVC.