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Proceedings Paper

Gray-world-assumption-based illuminant color estimation using color gamuts with high and low chroma
Author(s): Harumi Kawamura; Shunichi Yonemura; Jun Ohya; Akira Kojima
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Paper Abstract

A new approach is proposed for estimating illuminant colors from color images under an unknown scene illuminant. The approach is based on a combination of a gray-world-assumption-based illuminant color estimation method and a method using color gamuts. The former method, which is one we had previously proposed, improved on the original method that hypothesizes that the average of all the object colors in a scene is achromatic. Since the original method estimates scene illuminant colors by calculating the average of all the image pixel values, its estimations are incorrect when certain image colors are dominant. Our previous method improves on it by choosing several colors on the basis of an opponent-color property, which is that the average color of opponent colors is achromatic, instead of using all colors. However, it cannot estimate illuminant colors when there are only a few image colors or when the image colors are unevenly distributed in local areas in the color space. The approach we propose in this paper combines our previous method and one using high chroma and low chroma gamuts, which makes it possible to find colors that satisfy the gray world assumption. High chroma gamuts are used for adding appropriate colors to the original image and low chroma gamuts are used for narrowing down illuminant color possibilities. Experimental results obtained using actual images show that even if the image colors are localized in a certain area in the color space, the illuminant colors are accurately estimated, with smaller estimation error average than that generated in the conventional method.

Paper Details

Date Published: 4 February 2013
PDF: 8 pages
Proc. SPIE 8652, Color Imaging XVIII: Displaying, Processing, Hardcopy, and Applications, 86520C (4 February 2013); doi: 10.1117/12.2003961
Show Author Affiliations
Harumi Kawamura, Nippon Telegraph and Telephone Corp. (Japan)
Shunichi Yonemura, Shibaura Institute of Technology (Japan)
Jun Ohya, Waseda Univ. (Japan)
Akira Kojima, Nippon Telegraph and Telephone Corp. (Japan)

Published in SPIE Proceedings Vol. 8652:
Color Imaging XVIII: Displaying, Processing, Hardcopy, and Applications
Reiner Eschbach; Gabriel G. Marcu; Alessandro Rizzi, Editor(s)

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