La temperatura di colore. Ricerca fondamentale e pratica sociale

Colour has always fascinated scientists, artists and philosophers, but only in 1931 the Commission Intérnationale de l’Eclairage (CIE) could propose a quantitative evaluation of colour, based on the concept of ‘colour temperature’ (CT) . The historical path that leaded to the CIE method had started much earlier, with Newton, and pursued with Grassmann and Maxwell. The final thrust for a mathematisation of colour came from the economic and social need for a standardized system of lighting. Fundamental research necessary for standardization came from an interesting mixing of research centers of the Anglo-Saxon world: in the United States by the National Bureau of Standards and the National Electric Lamp Association Laboratory; in the UK by the National Physical Laboratory and Imperial College, London. CIE’s rules are still a fundamental reference in several industrial and research fields (electronics, dyes, food, cultural heritage). However, CT is not devoid of criticisms: it contradicts common use (‘hot’ colours exhibit lower CTs as compared to ‘cold’ colours); it is strictly conventional (a LED with CT~2700 K has an active area at 350 K).