Practical systems for measuring light and colour require an input relating to the performance of the human observer. There are at present seven internationally accepted functions recommended by the CIE together with two colour difference formulae. The range of validity of these functions and the development of more accurate functions is a subject of international concern.
An international collaboration is proposed, within the framework of EUROMET, to undertake an investigation of:
- the validity of existing systems of photometry with a view to establishing a generalised system of photometry covering all lighting conditions
- the range of validity of existing colour-difference formulae
- the relationship between brightness and luminance by ergonomic methods using computer-controlled displays
The agreeement between NPL and CNRS UPR 257 will be confined to the first of the three proposed investigations listed above.