Relative area and relative luminance combine to anchor surface lightness values

Abstract

The anchoring of lightness perception was tested in simple visual fields composed of only two regions by placing observes inside opaque acrylic hemispheres. Both side-by-side and center/surround configurations were tested. The results, which undermine Gilchrist and Bonato's (1995) recent claim that surrounds tend to appear white, indicate that anchoring involves both relative luminance and relative area. As long as the area of the darker region is equal to or smaller than the area of the lighter region, relative area plays no role in anchoring. Only relative luminance controls anchoring: The lighter region appears white, and the darker region is perceived relative to that value. When the area of the darker region becomes greater than that of the lighter region, relative area begins to play a role. As the darker region becomes larger and relative area shifts from the lighter region to the darker region, the appearance of the darker region moves toward white and the appearance of lighter region moves toward luminosity. This hitherto unrecognized rule is consistent with almost all of the many previous reports of area effects in lightness and brightness. This in turn suggests that a wide range of earlier work on area effects in brightness induction, lightness contrast, lightness assimilation, and luminosity perception can be understood in terms of a few simple rules of anchoring.

The place of white in a world of grays: A double-anchoring theory of lightness perception.

“…Li and Gilchrist (1999) took a clever step away from such complications by placing their observers' heads in a large illuminated hemispherical dome, the inside of which was divided into two parts, painted black and middle grey. An arrangement such as this meets the minimal conditions for perceiving a surface (Koffka, 1935, p. 111 Li and Gilchrist (1999). From "An Anchoring Theory of Lightness Perception" by A. Gilchrist, C. Kossyfidis, F. Bonato, T. Agostini, J. Cataliotti, X.…”

“…From "An Anchoring Theory of Lightness Perception" by A. Gilchrist, C. Kossyfidis, F. Bonato, T. Agostini, J. Cataliotti, X. Li, et al, 1999, Psychological Review, 106, p. 800. Copyright 1999 by the American Psychological Association.…”

A model of perceived dynamic range for HDR images

“…In order to develop a generic model that can truthfully predict PDR, sensory and cognitive processes involved in extraction of this attribute from complex stimuli need to be taken into account. Previous research has shown that the area of the brightest patches and the image topology affect the perception of lightness and contrast [17,19,26], and therefore should be considered in constructing such a PDR model. Furthermore, image contrast and colorfulness are important factors in visual perception and, based on previous findings [8,11,24,25], could be involved in the process related to the extraction of observed image attributes.…”

“…The human visual system then scales the rest to this maximum, generating an internal, scene-dependent scale of light and dark. Furthermore, Li and Gilchrist [17] observed that anchoring is affected by the relative area of the brightest patch.…”

“…The objective measurements proposed here are based on the insights of a previous pilot study [10], on achromatic HDR images, which inspired the work presented here; two measures (pixel-based DR and image key) are retained from the study and another three (area, contrast and colorfulness) are included based on analysis of that study's results and previous findings on these topics [17,24,11]. Three objective measures were used in the pilot study: dynamic range (DR), image key (IK) and spatial perceptual information (SI).…”