Colour Measurement

Abstract

Messrs. Smith, Guild and Donaldson's fears¹ of misconceptions were not at all justified. My letter² directed attention to certain general aspects of the physics of colour measurement. Emphasis was upon the need for knowledge in order to provide, for the concretest possible colour problems, the fullest possible analysis. Technical developments were a secondary consideration. I have not committed the elementary errors (a) of confusing the C.I.E. standards with the procedure, or (b) of thinking that errors in χ_C.I.E. values are possible owing to the procedure followed in the original experiments. The C.I.E. standards as such are exact. Also, I have no difficulties with the C.I.E. standard observer. All my references to the C.I.E. colorimetric system involved purely its place in a general physics of colour, The C.I.E. system of colorimetric standards, physical constants and agreed procedure is a convention which I do not regard as open to question, or as involved radically in this discussion. I do not question Messrs. Smith, Guild and Donaldson's appraisement of the merits of the C.I.E. system and have expressed parallel sentiments recently³.