The Recognition of Coloured Light Signals

Abstract

Part I describes the construction and calibration of a laboratory apparatus which combines light beams transmitted through colour filters in such proportions as to reproduce the intensity and energy distribution of all the coloured light signals generally used in practice.

Part 2 discusses the technique of signal colour recognition and gives the results of over 40,000 observations in the form of charts on which are drawn contours of the frequency of recognition of the simple colours under different conditions of illumination, range of possible colours, etc. The significance of these contours is briefly discussed, with a view to stating physical limits within which signal colours should lie.