A perceptual rate control algorithm based on luminance adaptation for HEVC encoders

Abstract

This paper proposes a rate control algorithm by selecting a proper quantization parameter (QP) based on perceptual luminance adaptation in a single-loop encoding fashion. In this paper, the proposed algorithm uses the visual characteristics of humans to adaptively decide the number of bits available for a pixel. Then, a base QP is selected based on the proposed R–λ model. The proposed rate control determines the range of QP based on the base QP and calculates the maximum and minimum bpps within that range. The optimal bpp is obtained from the bpp range by considering the visual characteristics of the human being, and the QP value is determined by the optical bpp through the proposed R–λ model. In the proposed rate control algorithm, the QP value is selected based on the R–λ model by considering the perceptual luminance adaptation model at the CTU level. The number of target bits is decided to decide the QP, subject to visual sensitivity based on JND thresholds. With the use of the proposed rate control algorithm, bits for non-noticeable regions can be saved, and the remaining bits can be consumed for perceptually noticeable regions to enhance the overall subjective quality with the similar amount of total bits. The proposed method shows lower average variances of bits and PSNR fluctuations. Also, the proposed method achieves an approximately 0.19 higher MOS value on average under DSCQS test, compared with the conventional R–λ model-based rate control algorithm.