A remarkable property of the hwnan visual system is that it manages to compress a 10-decade luminance range into a brightness range of about 3 decades. This paper deals with the question as to the compression mechanisms which the visual system uses for the luminance-brightness mapping. Data of two psychophysical experiments concerning solitary images are presented. The first experiment involves variation of the illumination level; in a second experiment the luminance range is expanded. The results indicate that three compression mechanisms are used, termed brightness constancy, contrast compression, and local adjustment of the environment. This so-called local adjustment, which is not reported in the literature as far as we know, asserts itself if the environment is less luminous in comparison with some central field and leads to a drop in the brightness of the direct surroundings. Furthermore. typical issues regarding sets of related images are worked out qualitatively in a demonstration.
|Number of pages||9|
|Journal||IPO Annual Progress Report|
|Publication status||Published - 1991|