A New Chromatic Adaptation Model for Different Illuminations

Illumination of a view environment illuminated by different illuminants can vary dramatically, which includes both the physical intensity (or luminance ) of the illumination and the chromaticity of the illumination. Several visual experiments show that Changes in illumination can cause the appearance of a color viewed under the corresponding illuminant to change. But dynamic mechanism of human visual system (HVS) has an ability of adaptation, which optimizes the visual response to particular view condition of illumination so that color appearance of the color object under different illuminants could be similar or same depending on the degree of adaptation of human view system. In some literatures, many chromatic adaptation models were proposed as the dynamic mechanism of the human view system. However, according to the studies of biopsychology and anatomy, changes of the range and the gain in cone sensitivity with wavelength intricately are both caused by changes of luminance of the illuminant. That is, luminance of the illuminant not only can influence the quantity of cones response but also can modify the spectral distribution of cones response of human eyes. So the paper proposes a new chromatic adaptation model which bases on eye´s adaptation of luminance and chromaticity with changes of illumination. The results of experiments are carried out to assess the performance of the proposed model by comparing that of CIECAT97[3] and CIECAT2000 [4] chromatic models.