Adaptive Quantization-Based HDR Video Coding with HEVC Main 10 Profile

Perceptual quantization (PQ) for HDR video coding has good perceptual uniformity in the luminance range with the modest bit-depth. However, the dynamic range of HDR videos is not well-used in PQ according to contents, especially for chroma channels. Thus, there exist the wasted dynamic ranges in PQ which cause detail loss and color distortions. In this paper, we propose adaptive quantization-based HDR video coding with HEVC Main 10 Profile. We perform adaptive mapping for 16bit to 10bit conversion based on cumulative distribution function (CDF), i.e. adaptive quantization, instead of linear mapping. First, we obtain CDF of each video frame using histogram analysis. Then, we conduct adaptive quantization based on CDF according to video contents, and generate metadata for inverse adaptive conversion in decoder, i.e. 10bit to 16bit conversion. Experimental results demonstrate that the proposed method reconstructs high-quality HDR videos and achieves a significant improvement in performance in terms of visual assessment and quantitative measurement.