Centre for Fine Print Research University of the West of England Centre for Fine Print Research

Reflectance, illumination, and edges in 3-D Mondrian colour constancy experiments

Author / co-author:
Carinna Parraman; A. Rizzi; J. McCann
Name of conference: 17th Color Imaging Conference: Color Science and Engineering Systems, Technologies, and Applications
Place: Albuquerque, New Mexico
Date: 11.09
Paper Presented by: Carinna Parraman
volume 17 isbn/issn: 978-0-89208-288-9
URL Links: http://www.imaging.org/IST/store/epub.cfm?abstrid=43645


We studied color constancy using a pair of 3-D Color Mondrian displays made of two identical sets of painted wooden shapes. There are only 6-chromatic, and 5-achromatic paints applied to nearly 100 block facets. The three-dimensional nature of these test targets adds shadows and multiple reflections not found in flat Mondrians. Observers viewed one set in uniform illumination--Low-Dynamic-Range(LDR); the other in highly directional non-uniform illumination-- High-Dynamic Range(HDR). Both 3-D Mondrians, were side-by-side, in the same room, at the same time. We used two measurement techniques to evaluate how well the appearances correlated with the object’s reflectances. First, we asked observers to compare the appearances of individual three-dimensional surfaces having identical reflectances, and recorded these changes in appearance using magnitude estimation. Second, an author painted a reproduction of the pair of Mondrians using watercolours. We measured the watercolour reflectances of the corresponding areas to quantify the change in appearances. Both measurements give us important data on how reflectance, illumination and image structure affect colour constancy. A constant paint does not exhibit perfect colour constancy, but rather shows significant shifts in lightness, hue and chroma in response to non-uniform illumination.

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