Weighted Chroma Downsampling and Luma-Referenced Chroma Upsampling for HDR/WCG Video Coding

摘要

High Dynamic Range and Wide Color Gamut (HDR/WCG) video coding adopts chroma downsampling and upsampling for coding efficiency, which causes degradation in visual quality. In this paper, we propose weighted chroma downsampling and luma-referenced chroma upsampling for H-DR/WCG video coding. We adopt ICtCp color space instead of YCbCr color space due to its advantage in chroma data processing. We perform weighted chroma downsampling based on the difference between neighbouring pixels before encoding. Moreover, we produce weights for chroma upsampling based on the correlation between luma and chroma data after decoding. Experimental results show that the proposed method successfully preserves edges in HDR/WCG videos while minimizing color distortion as well as outperforms Anchor in terms of both Bjonteggard delta bitrate (BD-rate) and HDR video quality measure (HDR-VQM).