Lars U. Borg

Evolution of the ICC profile connection space

The architecture used by the ICC to manage color is based on a device-independent color space called the Profile Connection Space (PCS). Each device relates its color space to that of the PCS, which allows source device profiles to be constructed without knowing the actual destination device and destination device profiles to be constructed without knowing the actual source device. The concept works well and has been widely adopted over the past several years. However, this widespread adoption has increasingly meant that profiles from various vendors will be connected in a color management system. In order for these profiles to work together, they must both implement the PCS in the same manner. Generally, this has been done well, but increasing quality expectations have shown that there are some areas in which the interoperability of profiles could be improved. The ICC has recently approved modifications to the PCS that address these issues. This paper will first describe the current ICC PCS, how it is used, and the interoperability problems that have been encountered. Next, it describes the PCS modification and shows how they improve the interoperability of ICC profiles.

Better Color Conversions for HDR and UHD TV Productions

The introduction of high-dynamic-range (HDR) color spaces and ultra-high-definitions (UHD) wide-color-gamut (WCG) color space in television creates a need to match colors on HDR and WCG displays with colors on conventional high-definition (HD) displays. Many contemporary color conversion methods that apply to conversion from HD to standard definition (SD), and color conversion methods mandated by current television standards, fail to produce a good color match when converting colors from the HDTV color space to HDR or WCG color spaces. This impairs the quality of HDTV contributions to HDR and UHD productions, as well as the quality of distribution of programs originating in HDR or UHD to HDTV viewers. This paper illustrates the color errors caused by the application of several of these conversion methods, and recommends one method, using display-referred colorimetry, for better color matching between narrow-gamut, wide-gamut and high-dynamic-range displays.