Illumination discrimination in real and simulated scenes

Radonjić, Ana; Pearce, Bradley; Aston, Stacey; Krieger, Avery; Dubin, Hilary; Cottaris, Nicolas P.; Brainard, David H.; Hurlbert, Anya

doi:10.1167/16.11.2

Cited by 42 publications

(73 citation statements)

References 39 publications

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“…This result seems contrary to previous findings of a "blue bias" in constancy [7], in particular, the finding of a "blue" shift in achromatic points measured for simulated illuminations [22] and the increased stability of color appearance under "bluish" changes in illumination [5,6,36], both of which imply better color constancy for "bluer" illuminations. In fact, these latter blue biases are distinct from each other [7], and neither contradicts the current findings.…”

Section: Discussioncontrasting

confidence: 99%

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The time course of chromatic adaptation under immersive illumination

Gupta¹,

Gross²,

Pastilha³

et al. 2020

Preprint

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AbstractChromatic adaptation is a major contributory mechanism to constancy, yet its extent depends on many factors - spectral, spatial and temporal - which vary between studies and hence may contribute to differences in reported constancy indices. Here, we use the achromatic adjustment method to characterise the temporal progression of chromatic adaptation under a wide range of illuminations in an immersive environment. We control both the spectral properties of the illumination at the eye and the spatial context of the adjusted surface, to disentangle global adaptation from local contrast effects. We measure the timecourse of chromatic adaptation by assessing achromatic adjustments in 6 discrete time slots over 340 seconds. We find that the change over time of the adaptation state, proximally indicated by colour constancy indices (quantified by the relative closeness of the perceptual whitepoint to the test illumination chromaticity), (a) can be modelled by a proportional rate growth function, typically requiring more than 5 minutes to stabilise; (b) depends on the contrast between the test surface and its background, specifically increasing with decreasing test-background contrast; and (c) is generally similar in both extent and rate for different test illumination chromaticities. Adaptation progression does not differ significantly between illuminations on or off the daylight locus. Our results highlight the importance of considering exposure duration and stimulus configuration, as well as the distance between the pre-adaptation (reference) and test illumination chromaticities, when using achromatic adjustment as a measure of colour constancy.

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Section: Discussioncontrasting

confidence: 99%

“…The current study also differs in aim from previous studies using the illumination discrimination task (IDT) [5,6,36]. These studies demonstrate a "blue bias", in that discriminability of abrupt changes in global illumination away from a reference illumination is worse in the bluish direction compared to yellowish, reddish or greenish.…”

Section: Discussioncontrasting

confidence: 74%

The time course of chromatic adaptation under immersive illumination

Gupta¹,

Gross²,

Pastilha³

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…This trend also appears for the R-G dichromats included in this study. However, our data do not support the influence of stimulus content in the CCT discrimination thresholds, as has been also previously reported [15]. The absence of a scene effect in the current research may arise from a lack of power due to a limited number of observers.…”

Section: Discussioncontrasting

confidence: 82%

Robust colour constancy in red-green dichromats

et al. 2017

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Colour discrimination has been widely studied in red-green (R-G) dichromats but the extent to which their colour constancy is affected remains unclear. This work estimated the extent of colour constancy for four normal trichromatic observers and seven R-G dichromats when viewing natural scenes under simulated daylight illuminants. Hyperspectral imaging data from natural scenes were used to generate the stimuli on a calibrated CRT display. In experiment 1, observers viewed a reference scene illuminated by daylight with a correlated colour temperature (CCT) of 6700K; observers then viewed sequentially two versions of the same scene, one illuminated by either a higher or lower CCT (condition 1, pure CCT change with constant luminance) or a higher or lower average luminance (condition 2, pure luminance change with a constant CCT). The observers’ task was to identify the version of the scene that looked different from the reference scene. Thresholds for detecting a pure CCT change or a pure luminance change were estimated, and it was found that those for R-G dichromats were marginally higher than for normal trichromats regarding CCT. In experiment 2, observers viewed sequentially a reference scene and a comparison scene with a CCT change or a luminance change above threshold for each observer. The observers’ task was to identify whether or not the change was an intensity change. No significant differences were found between the responses of normal trichromats and dichromats. These data suggest robust colour constancy mechanisms along daylight locus in R-G dichromacy.

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“…In addition, it provides a convenient interface that allows Matlab access to physics-based renderers. Our recent collaborative work with the Hurlbert lab on illumination discrimination [33,34] also takes advantage of RenderToolbox.…”

Section: Tools To Facilitate the Use Of Computer Graphics In Psychophmentioning

confidence: 99%

The perception of color and material in naturalistic tasks

Brainard

Cottaris

Radonjić

2018

Preprint

Self Cite

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Perceived object color and material properties help us to select and interact with objects. Because there is no simple mapping between the pattern of an object's image on the retina and its physical reflectance, our perception of color and material are made more useful through sophisticated visual computations. A long-standing goal in vision science is to describe how these computations work, particularly as they act to stabilize perceived color and material against variation in scene factors extrinsic to object surface properties, such as the illumination. If we take seriously the notion that perceived color and material are useful because they help guide behavior in natural tasks, then we need experimental that measure and models that describe how they are used in such tasks. To this end, we have developed selection-based methods and accompanying perceptual models for studying perceived object color and material. This focused review highlights key aspects of our work. It includes a discussion of future directions and challenges, as well as an outline of a computational observer model that incorporates early, known, stages of visual processing and that clarifies how early vision shapes selection performance. BrainardColor and Material

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Illumination discrimination in real and simulated scenes

Cited by 42 publications

References 39 publications

The time course of chromatic adaptation under immersive illumination

The time course of chromatic adaptation under immersive illumination

Robust colour constancy in red-green dichromats

The perception of color and material in naturalistic tasks

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