Colour-Rendering Tolerances and the Colour-Rendering Properties of Light Sources

Abstract

Good colour-rendering is defined relative to total radiator standards, and the problem of the determination of practical tolerances is outlined. Experiments are described from which a series of six spectral bands was derived, which could be used to determine colour-rendering tolerances and to classify the colour-rendering properties of a light source; the effect of variation of the luminance (relative to the reference source) of these bands, individually or in combination, was studied in detail, and a system of tolerances developed which can be used to indicate detailed spectral (band) variation or to give a single figure of merit (or classification) for the colour-rendering quality of a light source. The system has been tested by some large-scale trials on colour-rendering acceptability, and is applied to give a broad classification of normal types of British tubular fluorescent lamps. A comparison is made briefly of assessment on this basis with others that have been proposed.