engleski

Proposed Change in the Criteria for Metameric Colour Evaluation

A single metamerism index does not give enough information about the metameric properties of colours, and the colour difference DE is not sufficient to describe their varieties. For this reason, a procedure is suggested that describes metamerism in more detail with the following three parameters: 1. The colour temperature (or interval of colour temperature) of the light source (Planck radiator) for which the chromaticity difference between of the metameric colours is a minimum (the balancing colour temperature Tm or DTm). 2. The colour difference at Tm(DTm). 3. The chromaticity change in a determined chosen interval of the colour temperature which contains Tm (Dc 1000, Dc500 or otherwise). To estimate these parameters, the most suitable procedure is to determine the coordinates of two metameric colours for a series of colour temperatures in the CIE 1976 system (e.g. 2000K, 3000K … 9000K, 10000K). For each colour temperature the differences Du' and Dv' are calculated and plotted in the coordinate system with axes Du' and Dv'. The curve is obtained, from which Tm (or DTm), Dc and DEm are calculated in the usual way. Several examples of this process with the corresponding discussion are given. Because this process can be performed for any two colours, the conditions which DEm and Dc must fulfil in order for these two colours to be considered metameric must be established.

metameric properties of colours, chromaticity

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