Definition Problems of the Term “Lightness” in the History of its Development

Abstract

The article is devoted to the research of changes in lighting terminology on the example of one of the main properties of colour – lightness. The article substantiates the importance of the qualitative definition of terms for the professional understanding of various aspects of colorimetry and possibility of usage colour appearance models (CAM). Examples and comparisons of the wording of theterms of the CIECAM02 system are given based on variants from International Lighting Vocabularies (ILV) different years of release. The next is an example of the history of the development of the terms associated with different conditions of perception and definition of brightness, in particular, such as “lightness” and “subjective brightness”. The importance of the clear agreement between the terms and their definitions for the understanding, use, and development of the modern models and systems of colour perception is substantiated. The English-language and the Russian-language scientific sources are considered. The analysis of which demonstrates the dynamics of changes in the understanding of the term “Lightness”. Special attention is paid to the fate of the term in the Russian-language lighting literature, discrepancies in the interpretation of the term in various sources are shown, which can lead to a misunderstanding of modern colour appearance models. The comparison of the interpretation of the term“Lightness” is reviewing based on the English-language and the Russian-language scientific sources. The comparison helps to identify the reasons that led to the problems of definitions and understanding of this term. In the conclusion, the authors invite experts to discuss lighting terminology and harmonize Russian-language lighting literature with English-language literature. Also substantiates the importance of the participation of lighting engineering scientists in translations of different scientific literary sources devoted to colour perception. It is proposed to continue work on improving, and possibly a special reprinting of translations for the better understanding in the Russian lighting engineering literature.