Von Kries coefficients

A completely different model is given by Richards and Parks (1971). It is based on modified von Kries coefficients. If we assume that the sensor response functions have the shape of delta functions, then it is possible to transform a given color of a patch taken under one illuminant to the color of the patch when viewed under a different illuminant by multiplying the colors using three constant factors for the three channels. These factors are known as von Kries coefficients, as described in Section 4.6. The von Kries coefficients are defined as... 

The modified von Kries coefficients are then applied to the measured colors c, to obtain corresponding colors o, under another possibly neutral illuminant. 

The most popular implementation of the von Kries rule holds that the coefficients k (Equation 4.2) are adjusted to keep the adapted appearance of a reference white surface constant (Worthey and Brill, 1986). Thus, for example, if the cone absorptions of a perfect white under a given illuminant are then the adapted response for a surface under a second illuminant will be given by Equation 4.2 where the coefficients kj = Note that under this scheme the... 

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