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...s we did for our constancy index and use the achromatic loci to compute a diagonal mapping. We then apply this mapping to c g to obtain c db . We define our background index as BI � 1 � �cb � =-=cdb � . (2) �cb-=- � cg � This index is 1 if the locus shifts by an amount equal to the shift in background and 0 if the locus does not shift at all when the background is changed. In terms of constancy, the interp...

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...dinates of the second illuminant be c 2 � (u 2 , v 2), and the uv chromaticity coordinates of the equivalent illuminant be c d � (u d , v d). We define the constancy index CI by CI � 1 � �c2=-= � cd � . (1) �c2 �-=- c1 � This index is 1 if c d � c 2 (perfect constancy) and 0 if c d � c 1 (no effect of the illuminant). It behaves reasonably if c d lies near the line connecting c 1 and c 2 . We use the uv ch...

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...Brown, and White background surfaces. Table 1 provides the CIE xy chromaticities and luminances of the illuminants and background surfaces. Observers made achromatic settings at four CIELAB L* values =-=(50, 70, 90, 110)-=-. For each illuminant, CIELAB values were computed with respect to a white point defined by its CIE XYZ tristimulus coordinates. Since the computation of CIELAB coordinates depends on the white point,...