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Illumination discrimination for chromatically biased illuminations: Implications for color constancy

Lookup NU author(s): Stacey Aston, Professor Anya Hurlbert



This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


We measured discrimination thresholds for illumination changes along different chromatic directions starting from chromatically biased reference illuminations. Participants viewed a Mondrian-papered scene illuminated by LED lamps. The scene was first illuminated by a reference illumination, followed by two comparisons. One comparison matched the reference (the target); the other (the test) varied from the reference, nominally either bluer, yellower, redder, or greener. The participant's task was to correctly select the target. A staircase procedure found thresholds for discrimination of an illumination change along each axis of chromatic change. Nine participants completed the task for five different reference illumination conditions (neutral, blue, yellow, red, and green). We find that relative discrimination thresholds for different chromatic directions of illumination change vary with the reference illumination. For the neutral reference, there is a trend for thresholds to be highest in the bluer illumination-change direction, replicating our previous reports of a "blue bias" for neutral reference illuminations. For the four chromatic references (blue, yellow, red, and green), the change in illumination toward the neutral reference is less well discriminated than changes in the other directions: a "neutral bias." The results have implications for color constancy: In considering the stability of surface appearance under changes in illumination, both the starting chromaticity of the illumination and direction of change must be considered, as well as the chromatic characteristics of the surface reflectance ensemble. They also suggest it will be worthwhile to explore whether and how the human visual system has internalized the statistics of natural illumination changes.

Publication metadata

Author(s): Aston S, Radonjic A, Brainard DH, Hurlbert AC

Publication type: Article

Publication status: Published

Journal: Journal of Vision

Year: 2019

Volume: 19

Issue: 3

Online publication date: 29/03/2019

Acceptance date: 29/03/2019

Date deposited: 27/02/2019

ISSN (electronic): 1534-7362

Publisher: Association for Reseach in Vision and Ophthalmology


DOI: 10.1167/19.3.15

PubMed id: 30924843


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Funder referenceFunder name
102562/Z/13/ZWellcome Trust