Abstract
“Brightness sensation” or “vis ual clarity” of colored objects are affected significantly by changing the color rendering property of their illumination. This effect has been studied by a number of researchers. However, the cause of it has not been clarified.
Based on the careful inspection of the previous studies, we postulated that the above effect may de closely related to the change of the affection of contrast between colored objects under illumination existing in observer's visual field.
In order to confirm this postulation, we used 40 two-color combinations and the following four light sources; standard fluorescent lamp (Ra 63), three band type fluorescent lamp (Ra 84), incandescent lamp (Ra 100), and super highpressure sodium lamp (Ra 52). Their affections of contrast were estimated by using the predicting equations on the affections of two-color combinations derived by Nayatani et al. based on their spectral reflectance fanctions under each of the four lamps. The corresponding visual assessment confirmed the effectiveness of the predicting procedure.
The results confirmed that the affection of contrast is closely related to the “brightness sensation” and the “visual clarity” of colored objects under various illuminants.
