Conversion and Coding Practices for HDR/WCG ICTCP 4:2:0 Video

ICTCP is a colour difference signal representation recently standardized in Rec. ITU-R BT.2100. One design criteria of ICTCP for HDR/WCG imagery is to address issues in Non-Constant Luminance (NCL) Y'CbCr with HDR/WCG signals. In this paper, the superior performance of ICTCP in preserving constant luminance over the NCL Y'CbCr is analyzed in detail. The fundamental limitations of Y'CbCr luma adjustment algorithm which aims at fixing chroma subsampling artifact of Y'CbCr is discussed as well. This paper also provides guidance on signaling of ICTCP and feasible encoder settings with HEVC Main 10 codec. Experimental results suggest that for HDR content with real BT. 2100 (BT. 2020) colour gamut, to perform chroma subsampling and compression in ICTCP have significant value.