Inhomogeneous surrounds, conflicting frameworks, and the double-anchoring theory of lightness

Bressan, Paola

doi:10.3758/bf03193808

Cited by 25 publications

(17 citation statements)

References 18 publications

(38 reference statements)

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“…If such a theory was correct, then lightness would depend on the luminance polarity of the target vis-à-vis the noncontiguous field-assuming that there was any effect of polarity on induction strength at all-but it does not. For this reason, it cannot be explained by either of two leading theories of lightness computation: Gilchrist's anchoring theory and Bressan's double-anchoring theory (Bressan, 2006a(Bressan, , 2006b. In other words, the new experimental results are powerful enough to rule out a large class of otherwise plausible lightness models.…”

Section: Summary and Conclusion: Neural Lightness And Color Computatmentioning

confidence: 94%

Edge integration in achromatic color perception and the lightness-darkness asymmetry

Rudd

2013

Journal of Vision

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To maintain color constancy, the human visual system must distinguish surface reflectance-based variations in wavelength and luminance from variations due to illumination. Edge integration theory proposes that this is accomplished by spatially integrating steps in luminance and color contrast that likely result from reflectance changes. Thus, a neural representation of relative reflectance within the visual scene is constructed. An anchoring rule-the largest reflectance in the neural representation appears white-is then applied to map relative lightness onto an absolute lightness scale. A large body of data on human lightness judgments is here shown to be consistent with an edge integration model in which the visual system performs a weighted sum of steps in log luminance across space. Three hypotheses are proposed regarding how weights are applied to edges. First, weights decline with distance from the target surface whose lightness is being computed. Second, larger weights are given to edges whose dark sides point towards the target. Third, edge integration is carried out along a path leading from a common background field, or surround, to the target location. The theory accounts for simultaneous contrast; quantitative lightness judgments made with classical disk-annulus, Gilchrist dome, and Gelb displays; and perceptual filling-in lightness. A cortical theory of lightness in the ventral stream of visual cortex (areas V1 → V4) is proposed to instantiate the edge integration algorithm. The neural model is shown to be capable of unifying the quantitative laws of edge integration in lightness perception with the laws governing brightness, including Stevens' power law brightness model, and makes novel predictions about the quantitative laws governing induced darkness.

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Section: Summary and Conclusion: Neural Lightness And Color Computatmentioning

confidence: 94%

Edge integration in achromatic color perception and the lightness-darkness asymmetry

Rudd

2013

Journal of Vision

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“…When they say that "a grouping principle cannot be categorized as hard or soft before the context is known", they are confusing the dimension hard/soft with the dimension strong/weak. The "soft" principles are those that refer to the state of the observer, such as attention or past experience (Bressan, 2006b, p. 530;Bressan, 2006a); the "hard" principles are those that refer to the stimulus, such as proximity, common region, alignment, depth and shape similarity, luminance polarity and similarity-and this distinction holds before and after the context is known.…”

Section: Rationale Of Double Anchoringmentioning

confidence: 99%

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

Bressan

2006

Psychological Review

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1The specific grey shades in a visual scene can be derived from relative luminance values only when an anchoring rule is followed. The double-anchoring theory I propose in this paper, as a development of the anchoring theory of , assumes that any given region (a) belongs to one or more frameworks, created by Gestalt grouping principles, and (b) is independently anchored, within each framework, to both the highest luminance and the surround luminance. The region's final lightness is a weighted average of the values computed, relative to both anchors, in all frameworks. The new model not only accounts for all lightness illusions that are qualitatively explained by the anchoring theory but also for a number of additional effects, and it does so quantitatively, with the support of mathematical simulations.Keywords: lightness illusions, simultaneous lightness contrast, highest luminance, anchoring theories, illumination discounting All at once his white shirt blazed out, and I came out after him from shadow into full sunlight... -Ursula LeGuin, The Left Hand of DarknessOur visual world can be treated as a collection of groups of surfaces that belong together, either by design, like the black and white stripes on the zebra's back or the four regions in Figure 1a, or by accident, like the combination of sky fragments and tree branches through my window every morning at eight o'clock. Groups such as these have been called frameworks . Depending on the structural complexity of its context, a region can simultaneously belong to two or more nested frameworks, as is indeed the case with most objects in our visual experience. In the example of Figure 1a, what we may call the global 1 This article is a result of the cognitive dissonance stemming from my enchantment with the anchoring theory and my subsequent, and unplanned, experience of double-increment illusions. I am indebted to Peter Kramer, Dejan Todorović, Dave Rose, Ennio Mingolla, Luigi Burigana, Joe Cataliotti, Fred Bonato, Nicola Bruno, Tom Troscianko, Elias Economou, Suncica Zdravkovic, Piers Howe, Daniele Zavagno, and Fred Kingdom for their critical reading of one or the other of the several drafts of this manuscript. Special thanks to Alan Gilchrist for innumerable exchanges-an honor and a pleasure.Correspondence concerning this article should be addressed to Paola Bressan, Dipartimento di Psicologia Generale, Università di Padova, Via Venezia 8, 35131 Padova, Italy. E-mail: paola.bressan@unipd.it DOUBLE-ANCHORING THEORY OF LIGHTNESS framework (by temporarily ignoring the page and the visible rest of the room) is composed of two side-by-side local frameworks, each containing a grey patch on a uniform background. The interesting aspect of this familiar display is that the two patches are the same physical shade of grey, but the one in the black field appears lighter than the other. In spite of its apparent irrelevance to the issue of lightness, the multiple-framework idea, developed by Gilchrist and his collaborators, explains precisely why this should be so. The ...

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“…El mecanismo fisiológico parece estar situado en el córtex, si bien en este momento no se conoce con certeza. En el año 2006 Bressan [30,31] plantea la siguiente cuestión: "¿La luminosidad de una región se explica exclusivamente por la luminancia media de su alrededor?". La respuesta a esta pregunta es compleja y en el modelo planteado por Bressan la luminancia de la region de destino determina su luminosidad de dos maneras: indirectamente, formando un grupo de regiones envolventes, y directamente, mediante el anclaje a la lumancia más alta y a la luminancia media que rodea que cada uno de estos marcos.…”

Section: Antecedentesunclassified

Bezold effect evaluation through the design of an interactive desktop application

Tortajada-Montañana¹,

Fayos²,

Lengua³

et al. 2019

Opt. Pura Apl.

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At the end of XIX century Bezold described a Chevreul discovered effect named inverse contrast, expansion effect or Bezold effect. Recently, Tortajada, Montalvá and Aguilar have quantified it using Ronchi patterns represented on paper. In this work an interactive desktop application, which leads to a fast and efficient observer input measurement over Bezold variable color, spin and angle stripes, is presented. The new application's interface has two identical white circles on a neutral background. The samples to be compared appear inside them, both with the same chromatic values but in one there is a Bezold effect (due to Ronchi's grating) and in the other there is not (due to a solid concentric circle), so the observer will try to match each other. As a result we get, for each pair, the variation of L carried out to compensate the effect, and this variation is used to indicate the value of the Bezold effect for that sample.

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Inhomogeneous surrounds, conflicting frameworks, and the double-anchoring theory of lightness

Cited by 25 publications

References 18 publications

Edge integration in achromatic color perception and the lightness-darkness asymmetry

Edge integration in achromatic color perception and the lightness-darkness asymmetry

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

Bezold effect evaluation through the design of an interactive desktop application

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