December 2022
Volume 22, Issue 14
Open Access
Vision Sciences Society Annual Meeting Abstract  |   December 2022
Deviations from constancy in contrast matching over a wide range of luminances
Author Affiliations
  • Maliha Ashraf
    University of Liverpool
  • Sophie Wuerger
    University of Liverpool
  • Jasna Martinović
    University of Edinburgh
  • Rafal Mantiuk
    University of Cambridge
Journal of Vision December 2022, Vol.22, 4021. doi:
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      Maliha Ashraf, Sophie Wuerger, Jasna Martinović, Rafal Mantiuk; Deviations from constancy in contrast matching over a wide range of luminances. Journal of Vision 2022;22(14):4021.

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      © ARVO (1962-2015); The Authors (2016-present)

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The principle of contrast constancy in suprathreshold vision, first introduced by Georgeson and Sullivan (1975), stipulates that the perception of contrast remains invariant across different parameters of stimuli, including spatial frequency, size, retinal eccentricity, etc. Contrast constancy is also generally believed to hold over changes in luminance levels (Kulikowski, 1976; Peli, 1991), i.e., two stimuli with same physical contrast but different mean luminances will be perceived equal in contrast. However, the stimuli used in the studies investigating this kind of contrast matching varied within only 1 ~ 2.6 log units of luminance (cd/m^2). Modern high dynamic range (HDR) displays are capable of displaying content well over 1000 cd/m^2 and as low as 0.0001 cd/m^2. Our study aims to investigate whether contrast constancy also holds when the stimuli being matched vary across such large dynamic ranges. Our apparatus consisted of a reference and an HDR display, each visible to only one eye (haploscopic/dichoptic viewing). We used Gabor patches of 3 spatial frequencies (0.5, 1, and 4 cpd) with varying contrasts in achromatic and two chromatic directions. The reference display showed a reference stimulus at a fixed luminance level of 200 cd/m^2, whereas the HDR display showed similar test stimuli only varying in luminance levels ranging from 0.02 to 2,000 cd/m^2. Observers (n = 40) adjusted the contrast of the test stimuli until they perceived both reference and test contrasts to be the same. We found that contrast constancy does not hold over such a large range of luminance levels (5 log units). Stimuli over 20 cd/m^2 matched when their physical contrasts were the same for most conditions. But for lower luminances, much higher physical contrast was required for equal contrast perception. This deviation from constancy was also larger for lower spatial frequencies and lower pedestal suprathreshold contrasts.


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