Shade constancy is reached by chromatic adaptation. The Global Fee on Illumination defines white (adapted) as "a coloration stimulus that an observer that is [chromatically] tailored towards the viewing ecosystem would judge to generally be perfectly achromatic and to possess a luminance factor of unity. Sensible Vocabulary: related text and https://titusuexee.spintheblog.com/36300393/the-5-second-trick-for-rose-breasted-cockatoo