Television – Image signal processing circuitry specific to television – Color television signal processing
Patent
1996-12-04
1999-05-18
Lee, Michael
Television
Image signal processing circuitry specific to television
Color television signal processing
348642, 348453, 348386, 348222, H04N9/64
Patent
active
059055430
ABSTRACT:
The signals received by the three cameras of any color video system are determined by the reflectance properties of the objects in the scene and the spectral distribution function of the illuminant. Since the information of interest to the observer is determined by the scene and not by the illuminant i.e. what kind of objects, characterized by their reflectance properties, are in the scene, not how they are illuminated, it is desirable to correct the signals from the scene for the illuminant before the information is displayed on the CRT. According to the invention, a color video system employs the achromatic variable .xi., where .xi., 0.ltoreq..xi..ltoreq.1, and preferably also the chromatic variables .eta., .zeta., with the following characteristic properties: (1) they are illuminant-independent, (2) they have a representation invariant for a transformation of color matching functions, (3) they substantially optimize the system's power of discrimination under a reference illuminant, and (4) they can be chosen such that they are substantially perceptually meaningful.
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C. van Trigt, Smoothest reflectance functions: I. Definition and main results, J. Opt. Soc. Am. A, vol. 7, No. 10, pp. 1891-1904 (Oct. 1990).
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C. van Trigt, Metameric blacks and estimating reflectance, J. Opt. Soc. Am. A, vol. 11, No. 3, pp. 1003-1024 (Mar. 1994).
C. van Trigt, Estimating reflectance: How to discount the illuminant, Die Farbe, vol. 40, pp. 9-24 (1994).
Gallagher Thomas A.
Gordon David P.
Jacobson David S.
Lee Michael
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