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Proceedings Paper

Why do color transforms work?
Author(s): John C. Seymour
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Paper Abstract

Numerous papers have been written regarding techniques to translate color measurements from an RGB device into some standard color space. The papers seem to ignore the mathematical 'truth'...that the translation is impossible. Do these color transforms work, or under what conditions do they work, and what are the limitations. Why is it that they work. In this paper, light emitting diodes (LEDs) are viewed with a color video camera.It is seen that, for the spectra of LEDs, transforming from the camera color space the XYZ tristimulus space leads to very large errors. The problem stems from the fact that the RGB filter response are not a linear combination of XYZ responses. Next, it is shown that the transformation of CMYK halftones does not pose such difficulties.Here, it is found that a simple linear transform is relatively accurate, and some options to improve this accuracy are investigated. Several explanations are offered as to why transforms of CMYK are more accurate than transforms of LEDs. To determine which of the explanations is the most likely, linear transforms are applied to a variety of collections of colors.

Paper Details

Date Published: 4 April 1997
PDF: 9 pages
Proc. SPIE 3018, Color Imaging: Device-Independent Color, Color Hard Copy, and Graphic Arts II, (4 April 1997); doi: 10.1117/12.271586
Show Author Affiliations
John C. Seymour, Quad/Tech International (United States)

Published in SPIE Proceedings Vol. 3018:
Color Imaging: Device-Independent Color, Color Hard Copy, and Graphic Arts II
Giordano B. Beretta; Reiner Eschbach, Editor(s)

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