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Proceedings Paper

Appearance can be deceiving: using appearance models in color imaging
Author(s): Garrett M. Johnson
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Paper Abstract

As color imaging has evolved through the years, our toolset for understanding has similarly evolved. Research in color difference equations and uniform color spaces spawned tools such as CIELAB, which has had tremendous success over the years. Research on chromatic adaptation and other appearance phenomena then extended CIELAB to form the basis of color appearance models, such as CIECAM02. Color difference equations such as CIEDE2000 evolved to reconcile weaknesses in areas of the CIELAB space. Similarly, models such as S-CIELAB were developed to predict more spatially complex color difference calculations between images. Research in all of these fields is still going strong and there seems to be a trend towards unification of some of the tools, such as calculating color differences in a color appearance space. Along such lines, image appearance models have been developed that attempt to combine all of the above models and metric into one common framework. The goal is to allow the color imaging research to pick and choose the appropriate modeling toolset for their needs. Along these lines, the iCAM image appearance model framework was developed to study a variety of color imaging problems. These include image difference and image quality evaluations as well gamut mapping and high-dynamic range (HDR) rendering. It is important to stress that iCAM was not designed to be a complete color imaging solution, but rather a starting point for unifying models of color appearance, color difference, and spatial vision. As such the choice of model components is highly dependent on the problem being addressed. For example, with CIELAB it clearly evident that it is not necessary to use the associated color difference equations to have great success as a deviceindependent color space. Likewise, it may not be necessary to use the spatial filtering components of an image appearance model when performing image rendering. This paper attempts to shed some light on some of the confusions involved with selecting the desired components for color imaging research. The use of image appearance type models for calculating image differences, like S-CIELAB and those recommended by CIE TC8-02 will be discussed. Similarly the use of image appearance for HDR applications, as studied by CIE TC8-08, will also be examined. As with any large project, the easiest way to success is in understanding and selecting the right tool for the job.

Paper Details

Date Published: 29 January 2007
PDF: 9 pages
Proc. SPIE 6494, Image Quality and System Performance IV, 64940G (29 January 2007); doi: 10.1117/12.706154
Show Author Affiliations
Garrett M. Johnson, Apple Computer, Inc. (United States)

Published in SPIE Proceedings Vol. 6494:
Image Quality and System Performance IV
Luke C. Cui; Yoichi Miyake, Editor(s)

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