Apparent surface curvature affects lightness perception

Knill, David C.; Kersten, Daniel

doi:10.1038/351228a0

Cited by 205 publications

(160 citation statements)

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“…Other than changes in reflectance and illumination, the geometric layout of the scene and relationships between occluding, transparent, and connecting surfaces can have dramatic effects (7,11,42). The visual system can only partially discount these factors to achieve lightness constancy, for example through the use of stereo cues (8,42,43) or relatively simple heuristics for interpreting luminance changes (10,44).…”

Section: Discussionmentioning

confidence: 99%

“…On the one hand, lateral inhibition between retinal neurons filters out shallow intensity gradients, which are mostly caused by illumination effects (4,5). On the other hand, more complex factors also have an effect on lightness perception, such as object shape (6)(7)(8)(9) or the interpretation of transparent surfaces (10,11). However, eye movements have been almost completely neglected so far, even though a general influence of viewing behavior has been shown for some color constancy tasks (12)(13)(14)(15).…”

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confidence: 99%

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Optimal sampling of visual information for lightness judgments

Toscani

Valsecchi

Gegenfurtner

2013

Proc. Natl. Acad. Sci. U.S.A.

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The variable resolution and limited processing capacity of the human visual system requires us to sample the world with eye movements and attentive processes. Here we show that where observers look can strongly modulate their reports of simple surface attributes, such as lightness. When observers matched the color of natural objects they based their judgments on the brightest parts of the objects; at the same time, they tended to fixate points with above-average luminance. When we forced participants to fixate a specific point on the object using a gaze-contingent display setup, the matched lightness was higher when observers fixated bright regions. This finding indicates a causal link between the luminance of the fixated region and the lightness match for the whole object. Simulations with rendered physical lighting show that higher values in an object's luminance distribution are particularly informative about reflectance. This sampling strategy is an efficient and simple heuristic for the visual system to achieve accurate and invariant judgments of lightness.lightness constancy | lightness perception | visual perception | attention J udging the lightness of visual stimuli has been studied for centuries, since the original investigations by Weber (1) and Fechner (2). The light reaching the eye is the product of the illumination and the reflectance of the object, and also depends on the scene geometry (3). However, only the proportion of reflected light is an invariant property of the object and thus of great importance for vision. There are several well-established factors that support lightness constancy in the face of these challenges. On the one hand, lateral inhibition between retinal neurons filters out shallow intensity gradients, which are mostly caused by illumination effects (4, 5). On the other hand, more complex factors also have an effect on lightness perception, such as object shape (6-9) or the interpretation of transparent surfaces (10, 11). However, eye movements have been almost completely neglected so far, even though a general influence of viewing behavior has been shown for some color constancy tasks (12)(13)(14)(15). This finding is surprising because the visual system needs to sample the local properties of objects and this is accomplished by moving the eyes and the focus of spatial attention around. Because visual acuity, luminance sensitivity, contrast sensitivity, and color sensitivity change with retinal eccentricity (16-18), our visual system has to stitch together its representation of the world from many small samples to analyze the visual scene in detail. Peripheral vision is not only characterized by poor resolution, but also the appearance of basic visual features-like spatial frequency, luminance, or chromatic saturation-is distorted in the periphery of the visual field (19-22). Eye movements may then be used to select relevant information, even for stimuli that are above threshold in peripheral vision. We investigated whether the distribution of fixations on an object has an e...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Optimal sampling of visual information for lightness judgments

Toscani

Valsecchi

Gegenfurtner

2013

Proc. Natl. Acad. Sci. U.S.A.

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“…Many studies, however, have documented the relative independence of lightness͞brightness and luminances as such. Matching studies, in particular, have shown that the same luminances can be made to look dramatically different by their context (12,(23)(24)(25)(26)(27)(28)(29)(30)(31)(32). Because in many instances the activity of visual neurons is correlated with perceptual qualities rather than the physical properties of the stimulus (in the case of brightness see refs.…”

Section: Discussionmentioning

confidence: 99%

A probabilistic explanation of brightness scaling

Nundy

Purves²

2002

Proc. Natl. Acad. Sci. U.S.A.

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The perceptions of lightness or brightness elicited by a visual target are linked to its luminance by a nonlinear function that varies according to the physical characteristics of the target and the background on which it is presented. Although no generally accepted explanation of this scaling relationship exists, it has long been considered a byproduct of low-or mid-level visual processing. Here we examine the possibility that brightness scaling is actually the signature of a biological strategy for dealing with inevitably ambiguous visual stimuli, in which percepts of lightness͞brightness are determined by the probabilistic relationship between luminances in the image plane and their possible real-world sources.lightness ͉ luminance ͉ context T he relationship between the physical intensity of a light stimulus and its subjective perception has been debated since at least the middle of the 19th century (1-3). The central problem in ongoing attempts to rationalize this linkage has been the variability between luminance (i.e., the intensity of the light returned to the eye from object surfaces or light sources) and the sense of lightness or brightness elicited by the stimulus. Although intuition suggests that these sensations should scale in direct proportion to the intensity of the light that activates retinal receptors, the intensity of the sensation varies in a manner that is difficult to rationalize (Fig. 1). Thus, when targets are presented as luminance increments relative to a given background luminance, the scaling relationship is a power function referred to as Stevens' Law. Despite the canonical implication, the exponent of this function varies widely according to the size of the target, the duration of its presentation, the nature of the source, and other experimental variables (2, 4). Moreover, the relationship changes markedly and systematically as function of the intensity of the background luminance (6, 7). Although no consensus exists about the basis of these phenomena, many authors have interpreted them as consequences of neural processing early in the visual pathway (8-10).Although these effects are certainly initiated by low-and midlevel neural processing, the observed peculiarities of scaling may signify an important purpose. The possibility that we examine here is that the relationship between luminance and the resulting perceptions of lightness or brightness reflects a probabilistic strategy of visual processing demanded by the inherent ambiguity of visual stimuli. In these terms, the perceived intensity of any luminant stimulus is determined by the probability distribution of the possible underlying sources, or, more precisely, by the probable contributions of reflectance (R) and illumination (I) to the luminances experienced in the past (11). The amount of light associated with any part of a scene-that is, its local luminance-is typically the product of the I of that region and the R efficiency function(s) of the relevant object surfaces (12). In consequence, an infinite set of possible com...

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“…For example, lightness perception can depend on the geometric interpretation of a visual scene, such as curvature (Knill & Kersten, 1991;Pessoa, Mingolla, & Arend, 1996), transparency (Adelson, 1993), and depth (Gilchrist, 1977;Schirillo & Arend, 1995;Schirillo, Reeves, & Arend, 1990). Also, simply inducing the observer to interpret a scene differently (whether a luminance boundary is a shadow or an object border) affects lightness accordingly (Gilchrist, Delman, & Jacobsen, 1983).…”

Section: The Problem Of Lightness Constancymentioning

confidence: 99%

The maintenance of apparent luminance of an object.

Shimozaki¹,

Eckstein²,

Thomas³

1999

Journal of Experimental Psychology: Human Perception and Perfor

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Results from luminance discriminations with objects defined by apparent motion suggest an object-specific temporal integration of luminance. Further experiments suggested that this integration is weighted to favor the initial display of an object and involves the percept of surface reflectance (lightness). These results are consistent with the object-file metaphor suggested by D. Kahneman, A. Treisman, and B. Gibbs (1992), in which an object's perceived initial surface reflectance is assigned and maintained in an object file. A strategy is proposed in which the intrinsic properties of an object are assumed not to change over time. As intrinsic properties are generally invariant and possibly difficult to compute, this strategy would have the advantage of relatively high accuracy at relatively low computational cost.

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Apparent surface curvature affects lightness perception

Cited by 205 publications

References 14 publications

Optimal sampling of visual information for lightness judgments

Optimal sampling of visual information for lightness judgments

A probabilistic explanation of brightness scaling

The maintenance of apparent luminance of an object.

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