Factors affecting color appearance and measurement by psychophysical methods
Chromatic adaptation has been studied by applying methods of direct scaling to color appearances of stimuli perceived under different conditions of adaptation. This study differs from previous work in a number of ways. The color appearances of surface color stimuli were scaled by both magnitude estimation and magnitude production psychophysical methods. Changes in color appearances resulting from variations in correlated color temperature of adapting illumination, luminance factors of samples, illuininance, and surround induction conditions were scaled by a group of seven observers who had been trained to describe their perceptions in a uniform manner. This factorial approach to chromatic adaptation- influences on color appearance has yielded information about changes throughout a color solid rather than a single planar section of that solid. A distinction was made between absolute and relative attributes of color appearance. valuations of both internal and external consistency indicate that the data generated have relatively high precision and validity. The results indicate that chromatic adaptation induces smooth, continuous changes in color appearance. The nature of these changes depends upon correlated color temperature, luminance factor, and illuminance of surface color stimuli. Saturation, or colorfulness, is most susceptible to change and is highly dependent upon luminance factor and illuminance in addition to color temperature. These dependencies are systematic and explicit in the results presented here. Hue appearance of a given sample depends primarily upon color temperature of adapting illumination. Little or no change in hue was found for the range of variation in illuminance and luminance factor included in this study. In general, the hues of' all stimuli change with adaptation but there are important exceptions. The results do not support a linear model for the chromatic adaptation process.