Reflectance, illumination and edges

McCann, John; Parraman, Carinna; Rizzi, Alessandro

Abstract

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 watercolors. We measured the watercolor 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 color constancy. A constant paint does not exhibit perfect color constancy, but rather shows significant shifts in lightness, hue and chroma in response to non-uniform illumination. Published in
Seventeenth Color Imaging Conference: Color Science and Engineering Systems, Technologies, and Applications
Albuquerque, New Mexico; November 2009; p. 2-7; ISBN / ISSN: 978-0-89208-288-9

• Presentation Conference Type: Conference Paper (unpublished)
• Conference Name: Seventeenth Color Imaging Conference: Color Science and Engineering Systems, Technologies, and Applications
• Start Date: Nov 9, 2009
• End Date: Nov 13, 2009
• Publication Date: Nov 1, 2009
• Peer Reviewed: Peer Reviewed
• Volume: Volume
• Pages: 2-7
• Book Title: Seventeenth Color Imaging Conference: Color Science and Engineering Systems, Technologies, and Applications
• ISBN: 978-0-89208-288-9
• Keywords: reflectance, illumination, image structure, color constancy
• Public URL: https://uwe-repository.worktribe.com/output/1435451
• Publisher URL: http://www.imaging.org/IST/store/epub.cfm?abstrid=43645
• Related Public URLs: http://www.imaging.org/ist/conferences/cic/CIC%2017%20Preliminary%20Program.pdf