Look-up tables (LUTs) are frequently used in ICC profiles to establish relationships between a Profile Connection Space (e.g. CIELAB) and a device space (e.g. CMYK). The accuracy of an ICC profile is significantly influenced by the sampling method used to populate its LUTs. This paper investigates using polar coordinates for sampling of LUTs in the B2Ax tags of an iccMAX profile to convert from Profile Connection Space to device space. Additionally, a new sampling approach is proposed to achieve better perceptual uniformity of sampling between grid points using adjustment to LCH coordinates. The method uses DIN99d formula and CIEDE2000 color difference equation to sample grid points along C* and H* dimensions in a way that the distance between the grid points along these dimensions is much more perceptually uniform. Using such a strategy to build an iccMAX profile improves roundtrip accuracy while keeping the CLUT size unchanged compared to V4 ICC profiles with some cost in application performance.
Lin Luo, Maxim W. Derhak, "Perceptual Uniformity Improvement of Sampling with LCH Based Look-up Tables using iccMAX Profiles" in Proc. IS&T 26th Color and Imaging Conf., 2018, pp 390 - 395, https://doi.org/10.2352/ISSN.2169-2629.2018.26.390