An anchoring theory of lightness perception.

Abstract

A review of the field of lightness perception from Helmholtz to the present shows the most adequate theories of lightness perception to be the intrinsic image models. Nevertheless, these models fail on 2 important counts: They contain no anchoring rule, and they fail to account for the pattern of errors in surface lightness. Recent work on both the anchoring problem and the problem of errors has produced a new model of lightness perception, one that is qualitatively different from the intrinsic image models. The new model, which is based on a combination of local and global anchoring of lightness values, appears to provide an unprecedented account of a wide range of empirical results, both classical and recent, especially the pattern of errors. It provides a unified account of both illumination-dependent failures of constancy and background-dependent failures of constancy, resolving a number of long-standing puzzles.

When does grouping happen?

“…The conclusion that the gray dots' lightnesses are perceived relative to the dots within their own group is consistent with an early grouping hypothesis, and it is sufficient to explain the observed contrast effect. There are quite a few such reports of strong and consistent grouping effects producing contrast phenomena that are otherwise difficult to explain (e.g., Adelson, 1993;Gilchrist, Kossyfidis, Bonato, & Agostini, 1999;Todorovic, 1997;White, 1979). Such effects are not definitive evidence that grouping occurs before constancy processing, however, because lightness contrast and lightness constancy are not the same process.…”

A neuromorphic model for achromatic and chromatic surface representation of natural images

“…Note that the highest activity of the BHLA W module in Figure 4E is anchored to white ( 1JJ). This dependence of lightness on the size of a region is called Area Effect (Gilchrist et a!., 1999). The curve in each figure shows the signal profile along the horizontal middle section of the 2-D image.…”

“…As with the previous effects, the range of perceived reflectance increases, or dark ones look darker, when the staircase display is insulated by a white surround. The insets in Figure 12A illustrate the experimental displays and data (see Gilchrist et al, 1999 for a review). The black patch in the 5-staircase arrangement is perceived as middle gray (about 1.4 log perceived reflectance), while the same black patch surrounded by white insulation looks black (about 0.8 log perceived reflectance).…”

“…(1999) and Grossberg and Hong (2003) for reviews. No models had previously, however, explained lightness anchoring effects called Articulation, Configuration, Insulation, and the Area Effect (Gilchrist et a!., 1999). The present model simplifies a more biologically complete model of these phenomena to explain these and other lightness data, and to extend this simplified model to demonstrate an additional competence for processing natural color images under variable lighting conditions.…”

A model of perceived dynamic range for HDR images

“…Such a computation can be biased due to image noise or singularities, such as isolated pixels with extreme luminance values. Furthermore, such measures do not capture the complex behavior of the human visual system's (HVS) response and perception of lightness, including its intrinsic content-dependency [3]. The perceived dynamic range (PDR) of HDR content and its assessment in HDR conditions still remain unexplored.…”