High Dynamic Range (HDR) and Wider Colour Gamut (WCG) content represents a greater range of luminance levels and a more complete reproduction of colours found in real-world scenes. The current video distribution environments deliver Standard Dynamic Range (SDR) signal Y′CbCr. For HDR and WCG content, it is desirable to examine if such signal format still works well for compression, and to know if the overall system performance can be further improved by exploring different signal formats. In this paper, ITP (ICTCP) colour space is presented. The paper concentrates on examining the two aspects of ITP colour space: 1) ITP characteristics in terms of signal quantization at a given bit depth; 2) ITP compression performance. The analysis and simulation results show that ITP 10 bit has better properties than Y′CbCr-PQ 10bit in colour quantization, constant luminance, hue property and chroma subsampling, and it also has good compression efficiency. Therefore it is desirable to adopt ITP colour space as a new signal format for HDR/WCG video compression.