Practical extension to CIELUV color space to improve uniformity

A uniform chromaticity scale (UCS) in terms of just-noticeable difference (JND) to the human eye is important in industry and image processing, as well as for visually lossless image coding and noise evaluations. CIELUV which aims at microscopic uniformity to human perception, is widely used in color representation. However, its uniformity needs further improvements. In this paper, we demonstrate that a simple modification to CIELUV can further improve uniformity. Firstly, we optimized the CIELUV coefficient set while preserving its formulation to improve uniformity. This improved uniformity by 24%. Secondly, we slightly modified the formulation and obtained an optimized coefficient set. This improved uniformity by another 38%. Thirdly, we further optimized specifically inside the sRGB gamut, since the use of color contents conforming to the sRGB standard is ever increasing. This improved uniformity by yet another 3-5%.