Rapid mathematical methods for trichromatic colorimetry

Methods are suggested for reducing the labour involved in colorimetric transformations, with particular application to routine industrial measurements. The calibration of an instrument by measurement of illuminant B is replaced by measurement of a suitable stable filter and the illuminant in usual use. A nomographic method of conversion from instrument readings to the C.I.E. basis is suggested, and a graphical method is given for conversion to terms of hue and saturation. Scales are given for a graphical method of converting from the spectrophotometric curve of a coloured specimen to the trichromatic coefficients with a series of illuminants on the C.I.E. basis. The errors of these methods are estimated for comparison with the errors of observation on a Hilger-Guild trichromatic colorimeter.