High dynamic range and wide color gamut are currently being introduced to television and cinema. This extended information requires not only more efficient signal encodings, but also improved color spaces. Due to the increasing variation in display capabilities, it is desirable to have a color signal encoding that is not only suitable for efficient quantization but also for color volume mapping. While an efficient method for high dynamic range luminance encoding has been put forward, a similar encoding scheme for color difference signals is not yet available. We address this with a novel color space representation that can be used for both efficient encoding of high dynamic range and wide gamut color difference signals as well as color volume mapping. We compare the performance, robustness and complexity against other color spaces in a variety of usage scenarios.