Light Sources for Colour Matching

Abstract

Visual comparison of the colour of an article with a colour standard forms the basis of colour control in many industries. While the colour of the sample and the standard will only be a true match if their spectral reflectance characteristics are identical, this is not always practicable and the problem facing the colourist is to obtain the best match under the widest range of illuminants. North overcast daylight is generally regarded by colourists as being the most satisfactory source. The general characteristics of daylight with particular reference to variations in colour, the conclusions reached in surveys conducted to determine the preferred characteristics, and the variations between observers in determining a colour match are discussed. The matching of colours having a fluorescent component and the matching of fluorescent whites are also discussed. Artificial light sources which are available for colour matching work are compared. A source combining tungsten filament and fluorescent lamps which reproduces the required conditions is proposed.