Current CIE work to Achieve Physiologically Correct Colour Metrics

CIE colorimetry was introduced 65 years ago to describe the colorimetric properties of coloured lights and signals. Soon after establishment it turned out that it is most capable to describe the colorimetry of reflective media and is now widely applied in all branches of the colouring industries (e.g. in the textile, paper and automotive industry), where the aim is to produce as far as possible non-metameric matches, i.e. matches where the standard and the test samples show similar spectral reflectance. With the advance of modern light sources (gas discharge lamps with and without phosphors, emitting in narrow emission bands) and the use of colour monitors it became important to deal with metameric matches (where only the colour is the same, but the spectral power distribution is very different) and to find ways to describe not only colour matches but also colour appearance. CIE TC 1-36 re-examined the fundamental spectral sensitivity functions of the human observer and is currently working on a system of colorimetry based on the very best colour matching experiments, considering the different pre-retinal filtering agents and basic vision knowledge. It is hoped that these investigations will enable to build a colorimetric system that can span the 1° to 10° range of observation angle. CIE TC 1-43 extends this work by considering also light intensity effects, as at larger observation angles intensity dependent rod intrusion influences metameric colour matches. A very fundamental work on colour difference evaluation has just been finished and a new colour difference formula has been published, where different perturbing factors and location within the colour solid can be considered. There are several models of colour appearance described in the literature, and CIE TC 134 is engaged in testing and comparing these models and will eventually come up with a recommendation — if not for a generally accepted model, but for methods to thoroughly learn about the performance of these models. CIE TC 1-27 is collecting data for a specification of colour appearance differences between reflective media (printed samples) and self-luminous displays (colour monitors). As seen work is going on in many areas of colorimetry. The full paper will try to high-light recent achievements and will show trends of current research.