Can illumination estimates provide the basis for color constancy?

Granzier, Jeroen J. M.; Brenner, Eli; Smeets, Jeroen B. J.

doi:10.1167/9.3.18

Cited by 31 publications

(27 citation statements)

References 33 publications

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“…It is beyond our purpose to test precisely how well observers could perceive the illumination. Experiments that have tested observers' conscious perception of the illumination have failed to find a veridical percept (Granzier et al, 2009a).…”

Section: Discussionmentioning

confidence: 99%

“…Most of the changes between subsequent illuminants were quite evident to the observers. We did not use familiar objects in the scene for two reasons: First, one study found that the presence of familiar objects does not significantly lead to better matches of the illumination (Granzier et al, 2009a), and second, another study showed that the presence of familiar objects does not significantly help in achieving color constancy . The latter study was still important, as Granzier and colleagues (2009a) showed that there is no correlation between conscious estimates of the illumination and color constancy performance.…”

Section: The Scenementioning

confidence: 99%

“…Here it is worth mentioning that studies that have tested the amount of color constancy in human observers found that, although color constancy is on average quite robust (Granzier et al, 2009a(Granzier et al, , 2009b, it is far from perfect (for an overview see Foster, 2011). One could even speculate whether the reason for this imperfect color constancy might perhaps be to keep some information about the illuminant to guide the organisms' behavior, assuming that lightness and illumination cannot be represented independently.…”

Section: Introductionmentioning

confidence: 99%

“…These results suggest that illumination perception and color constancy are strongly linked. However, when it was explicitly tested to determine whether such a link exists, the results seem to indicate otherwise (Granzier, Brenner, & Smeets, 2009a;Granzier, Nijboer, Smeets, & Brenner, 2005;Granzier, Smeets, & Brenner, 2012). These results make the precise relationship between color constancy and illumination perception complex.…”

Section: Introductionmentioning

confidence: 99%

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Variations in daylight as a contextual cue for estimating season, time of day, and weather conditions

Granzier

Valsecchi²

2014

Journal of Vision

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Experience and experiments on human color constancy (i.e., Arend & Reeves, 1986; Craven & Foster, 1992) tell us that we are capable of judging the illumination. However, when asked to make a match of the illuminant's color and brightness, human observers seem to be quite poor (Granzier, Brenner, & Smeets, 2009a). Here we investigate whether human observers use (rather than match) daylight for estimating ecologically important dimensions: time of year, time of day, and outdoor temperature. In the first three experiments we had our observers evaluate calibrated color images of an outdoor urban scene acquired throughout a year. Although some observers could estimate the month and the temperature, overall they were quite poor at judging the time of day. In particular, observers were not able to discriminate between morning and afternoon pictures even when they were allowed to compare multiple images captured on the same day (Experiment 3). However, observers could distinguish between midday and sunset and sunrise daylight. Classification analysis showed that, given a perfect knowledge of its variation, an ideal observer could have performed the task over chance only considering the average chromatic variation in the picture. Instead, our observers reported using shadows to detect the position of the sun in order to estimate the time of day. However, this information is highly unreliable without knowledge of the orientation of the scene. In Experiment 4 we used an LED chamber in order to present our observers with lights whose chromaticity and illuminance varied along the daylight locus, thus isolating the light cues from the sun position cue. We conclude that discriminating the slight variations in chromaticity and brightness, which potentially distinguish morning and afternoon illuminations, lies beyond the ability of human observers.

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Section: Discussionmentioning

confidence: 99%

Section: The Scenementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Variations in daylight as a contextual cue for estimating season, time of day, and weather conditions

Granzier

Valsecchi²

2014

Journal of Vision

Self Cite

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“…It is clear that a model based on the gray world assumption (e.g., [1]) would fail to predict the effect of chromatic orientation, since it only relies on the mean chromaticity in the scene. There are a number of studies, however, in which the chromatic distribution of the visual scene is probed to derive information about the chromaticity of the illuminant (e.g., [2,[29][30][31][32]). But even if we suppose that this would result in the correct estimation of the exact illuminant color, it would still not predict that one illuminant leads to a higher color fidelity than another.…”

Section: Discussionmentioning

confidence: 99%

Effects of chromatic image statistics on illumination induced color differences

et al. 2013

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We measure the color fidelity of visual scenes that are rendered under different (simulated) illuminants and shown on a calibrated LCD display. Observers make triad illuminant comparisons involving the renderings from two chromatic test illuminants and one achromatic reference illuminant shown simultaneously. Four chromatic test illuminants are used: two along the daylight locus (yellow and blue), and two perpendicular to it (red and green). The observers select the rendering having the best color fidelity, thereby indirectly judging which of the two test illuminants induces the smallest color differences compared to the reference. Both multicolor test scenes and natural scenes are studied. The multicolor scenes are synthesized and represent ellipsoidal distributions in CIELAB chromaticity space having the same mean chromaticity but different chromatic orientations. We show that, for those distributions, color fidelity is best when the vector of the illuminant change (pointing from neutral to chromatic) is parallel to the major axis of the scene's chromatic distribution. For our selection of natural scenes, which generally have much broader chromatic distributions, we measure a higher color fidelity for the yellow and blue illuminants than for red and green. Scrambled versions of the natural images are also studied to exclude possible semantic effects. We quantitatively predict the average observer response (i.e., the illuminant probability) with four types of models, differing in the extent to which they incorporate information processing by the visual system. Results show different levels of performance for the models, and different levels for the multicolor scenes and the natural scenes. Overall, models based on the scene averaged color difference have the best performance. We discuss how color constancy algorithms may be improved by exploiting knowledge of the chromatic distribution of the visual scene.

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Categorical color constancy under RGB‐LED light sources

Liao

Yan

et al. 2018

Color Research & Application

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The light-emitting diode (LED)-based light sources have been widely applied across numerous industries and in everyday practical uses. Recently, the LED-based light source consisting of red, green and blue LEDs with narrow spectral bands (RGB-LED) has been a more preferred illumination source than the common white phosphor LED and other traditional broadband light sources because the RGB-LED can create many types of illumination color. The color rendering index of the RGB-LED, however, is considerably lower compared to the traditional broadband light sources and the multi-band LED light source (MB-LED), which is composed of several LEDs and can accurately simulate daylight illuminants. Considering 3 relatively narrow spectral bands of the RGB-LED light source, the color constancy, which is referred to as the ability of the human visual system to attenuate influences of illumination color change and hold the perception of a surface color constant, may be worse under the RGB-LED light source than under the traditional broadband light sources or under the MB-LED. In this study, we investigated categorical color constancy using a color naming method with real Munsell color chips under illumination changes from neutral to red, green, blue, and yellow illuminations. The neutral and 4 chromatic illuminants were produced by the RGB-LED light source. A modified use of the color constancy index, which describes a centroid shift of each color category, was introduced to evaluate the color constancy performance. The results revealed that categorical color constancy under the 4 chromatic illuminants held relatively well, except for the red, brown, orange, and yellow color categories under the blue illumination and the orange color category under the yellow illumination. Furthermore, the categorical color constancy under red and green illuminations was better than the categorical color constancy under blue and yellow illuminations. The results indicate that a color constancy mechanism in the visual system functions in color categories when the illuminant emits an insufficient spectrum to render the colors of reflecting surfaces accurately. However, it is not recommended to use the RGB-LED light source to produce blue and yellow illuminations because of the poor color constancy.

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Can illumination estimates provide the basis for color constancy?

Cited by 31 publications

References 33 publications

Variations in daylight as a contextual cue for estimating season, time of day, and weather conditions

Variations in daylight as a contextual cue for estimating season, time of day, and weather conditions

Effects of chromatic image statistics on illumination induced color differences

Categorical color constancy under RGB‐LED light sources

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