Brightness-luminance relationships in an interior

Abstract

Some four thousand numerical estimates of the brightness of the various objects, room surfaces and sources in a particular interior, under different lighting conditions, have been made by thirty-six observers. Details of this experiment are given in this paper, the precision of brightness measurement is discussed and the resulting irregular brightness-luminance relationships are presented. These results are examined together with those of related brightness studies and a pair of simple power-law relationships are put forward which are considered adequate approximations for interior lighting design purposes.