A comparison has been made between results of interocular brightness matching and of asking for brightness estimations. The matching results have been translated by applying a power function transformation to the luminance values of the comparison field. The translated results of brightness matching turned out to be completely analogous to results of subjective estimations. By means of plotting the results in terms of subjective estimations relations between brightness and luminance under induction could be easier described. This has been shown in respect to effects of field configurations on these relations. Description of the relations in terms of a concept "visual gradation" analogous to gradation of photographic material has been proposed. Under induction the visual gradation has been increased for test luminances below a critical value depending on the inducing luminance.
Abstract