Phenomena of apparent lightness interpreted by the recognized visual spaceof illumination

Many experimental results have been reported which demonstrated deviation o f the apparent lightness from the calculated lightness based on spectral re flectance, and these have caused debate among researchers as to the models to explain them. The judgement of lightness of objects that we see in the o utside world is one of the most important tasks in our daily life. We propo sed the recognized visual space of illumination, RVSI, as a three dimension al recognition constructed in the brain for the outside world, and showed t hat the apparent lightness was determined in relation to the size of the RV SI. In the present paper the concept was applied tu various results of ligh tness experiments such as the White effect and simultaneous contrast, and b ased on the proposition that an observer first builds a three dimensional R VSI from a two dimensional pattern and the lightness of a test patch was ju dged in relation to the size of this RVSI, the results were then globally a nd nicely explained. A new demonstration of a pattern was proposed to give different apparent lightness for patches with the same physical lightness t o strengthen the proposition. The importance of distinguishing between a te st patch and a surrounding field was emphasized when one does a lightness e xperiment and interprets: the results.