Ambiguities in Colour Constancy and Shape from Shading

Jakobsson, Torbjörn; Bergström, Sten Sture; Gustafsson, Karl-Arne; Fedorovskaya, Elena A.

doi:10.1068/p260531

Cited by 4 publications

(3 citation statements)

References 8 publications

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“…The low-tech method used in our present experiment was chosen to give colour constancy but, despite this, there is a shift of the mode of appearance from surface colour to film colour. Such a shift in reverse directions, from coloured light to surface colours and from constancy to lack of constancy, appeared in our earlier study of the AMBEGUJAS phenomenon (Jakobsson et al 1997) and the constancy versus lack of constancy has been discussed by Bergstro« m (2004).…”

Section: Discussionsupporting

confidence: 55%

“…Another example of such a shift is reported by Logvinenko and Menshikova (1994) who used`upside^down optics' to shift from perceived cast shadow to a spot of surface colour when a cone shape shifted to a funnel and its cast shadow shifted to a spot of surface colour. All the three alternative perceived shapes (roof, ceiling, and tile) have been reported here, but in our earlier study on AMBEGUJAS (Jakobsson et al 1997) only two alternative shapes were reported (roof and tile). No concave alternative was reported.…”

Section: Discussionmentioning

confidence: 49%

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Concave and Convex Phases in Ambiguous Figures Showing Colour Shifts. Mach's Figure and the Ambegujas Phenomenon

Bergström

Gustafsson²

2011

Perception

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Two ambiguous figures (Mach's book-figure and the AMBEGUJAS phenomenon) have been studied. They show colour shifts synchronised with the shifts of their alternative phases. The perceived concave phase appeared to have chromatic surface colour, but the perceived convex phase can appear to be in coloured illumination and shadow (film colour). The two perceived reversible shapes of the Mach figure (the book and the tent) and the three perceived alternative shapes of the Mondrians used in the AMBEGUJAS phenomenon (a roof, a ceiling, and a tile) all can appear to have chromatic surface colours in their concave phases but appear to have coloured illumination and shadow in their convex phases.

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Section: Discussionsupporting

confidence: 55%

Section: Discussionmentioning

confidence: 49%

Concave and Convex Phases in Ambiguous Figures Showing Colour Shifts. Mach's Figure and the Ambegujas Phenomenon

Bergström

Gustafsson²

2011

Perception

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“…Colour saturation has been studied in the AMBEGUJAS situations (Jakobsson et al 1997), but the saturation of the perceived illumination has not been studied at the same time.…”

Section: Colour Constancymentioning

confidence: 99%

The AMBEGUJAS Phenomenon and Colour Constancy

Bergström

2004

Perception

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The AMBEGUJAS phenomenon is a reversible flat figure that is spontaneously shifting between two apparent 3-D shapes-'tile' and 'roof'. 2-D perceptions have very rarely been reported. Tied to the shifts between the tile and roof shapes are remarkable changes of perceived colour. In our example, the tile appears to have orange (top half) and blue-green (bottom half) surface colours in white light. The roof appears grey but in an orange illumination and with a blue-green shadow. This phenomenon appears whether a grey display is presented in two coloured illuminations, or a chromatic display with two surface colours (orange and blue-green) is presented in white light. In the coloured illuminations the tile is an example of non-constancy, since its colours are non-veridical colour perceptions. The centre stripe of the display appears to have the same orange and blue-green colours as the lateral stripes but in a shadow. This seems like a colour constancy in a non-constancy situation. An alternative to the classical definition of colour constancy is discussed.

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Perceiving light versus material

Kingdom

2008

Vision Research

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Humans rarely confuse variations in light intensity, such as shadows, shading, light sources and specular reflections, from variations in material properties, such as albedo or pigment. This review explores the cues, or regularities in the visual world that evidence suggests vision exploits to discriminate light from material. These cues include luminance relations, figural relations, 3D-shape, depth, colour, texture, and motion. On the basis of an examination of the cues together with the behavioural evidence that they are used by vision, I propose a set of heuristics that may guide vision in the task of distinguishing between light and material. I argue that while there is evidence for the use of these heuristics, little is known about their relative importance and the manner in which they are combined in naturalistic situations where there are multiple cues as to what is light and what is material. Finally, I discuss two theoretical frameworks, the generic view principle and Bayesian estimation, that are beginning to help us understand the visual processes involved in distinguishing between light and material.

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Ambiguities in Colour Constancy and Shape from Shading

Cited by 4 publications

References 8 publications

Concave and Convex Phases in Ambiguous Figures Showing Colour Shifts. Mach's Figure and the Ambegujas Phenomenon

Concave and Convex Phases in Ambiguous Figures Showing Colour Shifts. Mach's Figure and the Ambegujas Phenomenon

The AMBEGUJAS Phenomenon and Colour Constancy

Perceiving light versus material

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