Samenvatting
The paper analysis work relating to the study of the visibility curve as well as of the spectral efficiency of radiations characterized by the visual acuity and the contrast sensivity. Methods of calculation of the visual efficiency for various typesof light sources are precented. The results of an investigation of the brightness-luminance relation ate analysed. Recommendations regarding the photometric conditions for the small luminance range are indicated. Certain physiological characteristics of the spectral sensitivity of the eye are examined.