The properties of constancy models based on the proportionality rule of von Kries are examined in a series of simplified examples. It is found that the breadth of receptor-sensitivity functions causes metamerism, thwarting color constancy. Overlap of these functions limits the accuracy of von Kries adaptation for a more subtle reason: it causes nonzero off-diagonal elements in the transformation matrix relating object reflectance to receptor stimulations. Such off-diagonal elements make von Kries adaptation an inexact color-constancy scheme, even when the illuminant is restricted to prevent metamerism.
© 1986 Optical Society of America
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