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Proceedings Paper

Spatial contrast and scatter: opposing partners in sensations
Author(s): John J. McCann
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Paper Abstract

We are all familiar with a number of contrast experiments in which two identical reflectance patches appear different in different spatial contexts. Examples are simultaneous contrast and White's effect. The simultaneous contrast experiment places a gray patch in a white surround to make the gray appear darker. In this case, identical radiances at the target are not identical radiances at the retina. If we want equal retinal radiances, we need, with the aid of an intraocular scatter model, to make a display that has lower display radiances in a white surround. This paper compares a number of scatter-corrected contrast experiments with their uncorrected counterparts. In simultaneous contrast, correcting for scatter shows that the underlying spatial interactions have a larger effect on sensations that in uncorrelated displays. Scatter and contrast tend to cancel, but in this case, they just reduce the apparent size of the spatial interaction. White's effect is just the opposite. The contrast effect and scatter add. In this case, correcting for scatter reduces the size of the effect, but does not overpower it. This paper describes a number of contrast experiments corrected for scattered light. The paper further discusses the magnitude of lightness shifts due to spatial interactions after scatter has been corrected. Scatter cannot explain White's Effect, although correction for scatter reduces its magnitude.

Paper Details

Date Published: 19 May 1999
PDF: 8 pages
Proc. SPIE 3644, Human Vision and Electronic Imaging IV, (19 May 1999);
Show Author Affiliations
John J. McCann, McCann Imaging (United States)


Published in SPIE Proceedings Vol. 3644:
Human Vision and Electronic Imaging IV
Bernice E. Rogowitz; Thrasyvoulos N. Pappas, Editor(s)

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