Does colour constancy exist?

Foster, David H.

doi:10.1016/j.tics.2003.08.002

Cited by 102 publications

(75 citation statements)

References 44 publications

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“…However, researchers have previously reported that observers do not always achieve complete, satisfactory matches in asymmetric matching experiments involving color or lightness (Brainard, Brunt, & Speigle, 1997;Foster, 2003;. The results of Logvinenko and Maloney indicate that perceived dissimilarity is affected by at least two perceptual dimensions corresponding to surface albedo and intensity of illumination.…”

Section: Discussionmentioning

confidence: 99%

A scaling analysis of the snake lightness illusion

Logvinenko

Petrini

Maloney

2008

Perception & Psychophysics

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Section: Discussionmentioning

confidence: 99%

A scaling analysis of the snake lightness illusion

Logvinenko

Petrini

Maloney

2008

Perception & Psychophysics

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“…These include color constancy, whereby the brain at least partly removes the effect of changes in environmental light on color perception (Maloney and Wandell, 1986;Hulbert, 1999;Foster, 2003). However, the mechanisms underlying color constancy are not fully understood (Hulbert, 2007).…”

Section: Discussionmentioning

confidence: 99%

Color contrast and stability as key elements for effective warning signals

2014

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Vivid warning signals (aposematism) have evolved repeatedly throughout the animal kingdom. However, relatively few studies consider what makes an effective signal, in terms of preventing attack and promoting avoidance learning by predators. Signal form varies substantially among and sometimes within species, but there has also been apparent convergence on relatively few main color types. We aimed to determine why warning signals often combine red, orange, yellow, and black colors, and specifically to determine whether these colors provide highly salient and reliable visual signals under a range of environmental conditions. Using digital image analysis, we modeled ladybird (ladybug) coloration to an avian visual system. We calculated the contrast of several different ladybird species against an average green background, based on predicted opponent color channel responses in bird vision. Our results suggest that longwave colors (i.e., red, orange) are more contrasting than colors such as blue, against green natural backgrounds. Moreover, these colors yield relatively unchanging (stable) signals throughout the day and under different weather conditions. These analyses show how aposematic signals have evolved under selection to be more effective by being more conspicuous and reliable to the visual system of their potential avian predators.

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“…It is vitally important from the ecological point of view to distinguish between these (e.g., Gibson, 1979). Human observers have been found to be rather good at distinguishing between changes produced by illumination and reflectance in visual scenes (e.g., Craven & Foster, 1992;Foster et al, 2001;Foster, 2003;Kingdom, 2008).…”

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confidence: 99%

Lightness constancy and illumination discounting

Logvinenko

Tokunaga

2011

Atten Percept Psychophys

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Contrary to the implication of the term "lightness constancy", asymmetric lightness matching has never been found to be perfect unless the scene is highly articulated (i.e., contains a number of different reflectances). Also, lightness constancy has been found to vary for different observers, and an effect of instruction (lightness vs. brightness) has been reported. The elusiveness of lightness constancy presents a great challenge to visual science; we revisit these issues in the following experiment, which involved 44 observers in total. The stimuli consisted of a large sheet of black paper with a rectangular spotlight projected onto the lower half and 40 squares of various shades of grey printed on the upper half. The luminance ratio at the edge of the spotlight was 25, while that of the squares varied from 2 to 16. Three different instructions were given to observers: They were asked to find a square in the upper half that (i) looked as if it was made of the same paper as that on which the spotlight fell (lightness match), (ii) had the same luminance contrast as the spotlight edge (contrast match), or (iii) had the same brightness as the spotlight (brightness match). Observers made 10 matches of each of the three types. Great interindividual variability was found for all three types of matches. In particular, the individual Brunswik ratios were found to vary over a broad range (from .47 to .85). That is, lightness matches were found to be far from veridical. Contrast matches were also found to be inaccurate, being on average, underestimated by a factor of 3.4. Articulation was found to essentially affect not only lightness, but contrast and brightness matches as well. No difference was found between the lightness and luminance contrast matches. While the brightness matches significantly differed from the other matches, the difference was small. Furthermore, the brightness matches were found to be subject to the same interindividual variability and the same effect of articulation. This leads to the conclusion that inexperienced observers are unable to estimate both the brightness and the luminance contrast of the light reflected from real objects lit by real lights. None of our observers perceived illumination edges purely as illumination edges: A partial Gelb effect ("partial illumination discounting") always took place. The lightness inconstancy in our experiment resulted from this partial illumination discounting. We propose an account of our results based on the two-dimensionality of achromatic colour. We argue that large interindividual variations and the effect of articulation are caused by the large ambiguity of luminance ratios in the stimulus displays used in laboratory conditions.

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Does colour constancy exist?

Cited by 102 publications

References 44 publications

A scaling analysis of the snake lightness illusion

A scaling analysis of the snake lightness illusion

Color contrast and stability as key elements for effective warning signals

Lightness constancy and illumination discounting

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