Method and apparatus for determining ambient light and surface r

Details Method and apparatus for determining ambient light and surface r Method and apparatus for determining ambient light and surface r

1988-12-02

1991-02-12

Gruber, Felix D.

Boots, shoes, and leggings

250226, 356402, 364521, G06F 1562, G01J 350, G01N 2155

Patent

active

049929631

ABSTRACT:
An apparatus for dividing light reflected by an illuminated surface into constituent parts of illuminating light and surface spectral reflectance of the surface. The apparatus includes a receiving device for receiving signals representing measured spectral power distribution Im(.lambda.) of the light reflected by the illuminated surface. The apparatus generates a weighting coefficient .epsilon..sub.i for each of M illuminant basis functions EB.sub.i (.lambda.) for describing the illuminating light. Weighting coefficients .sigma..sub.j for each of N reflectance basis functions Sb.sub.j (.lambda.) are generated to describe the reflectance of the surface. The apparatus compares an approximation Ia(.lambda.) of the measured spectral power distribution Im(.lambda.), Ia(.lambda.) being defined by the relation: ##EQU1## where the set of product pairs Eb.sub.i (.lambda.)Sb.sub.j (.lambda.) is linearly independent.
Different weighting coefficients are regenerated until said Ia(.lambda.) and said Im(.lambda.) are generally equal. Signals representing at least one of the constituent parts of illuminating light and said surface spectral reflectance are generated based on the weighting coefficients .sigma..sub.i and .sigma..sub.j which make said Ia(.lambda.) generally equal to said Im(.lambda.). The apparatus has an output device for outputting the signals.

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