Hue perception under scotopic light levelsvpl.uic.edu/presentations/vss2011scotopic.pdf · 2016. 1....
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Spacing = 0 deg Spacing = 0.5 deg Spacing = 1 deg Duration (sec) 1 0.5 2 0.1 Simple Context −80% −40% 40% 80% −80% −40% 40% 80% −80% −40% 40% 80% Contrast Complex Context Hue perception under scotopic light levels Sarah L. Elliott 1 & Dingcai Cao 1,2 1 Institute for Mind and Biology, University of Chicago, Chicago, IL, USA 2 Section of Ophthalmology and Vision Science, University of Chicago, Chicago, IL, USA Background No Context Results A 1 deg test ring was viewed at a 7 deg retinal eccentricity on a CRT covered by neutral density filters. The test luminance was approximately -2.6 log scotopic cd/m 2 (-4 log photopic cd/m 2 ) . The test ring was surrounded by either 2 (simple context - both equal luminance, either higher or lower than test) or 4 (complex context - 2 higher, 2 lower luminance than test) 1 deg inducing rings. Stimulus duration (4 temporal presentations), inducer spacing (3 conditions) and contrast (4 conditions) were varied for both simple and complex context. A hue scaling technique was used to measure perceived hue and saturation. Complex Context Spacing 0 deg 0.5 deg 1 deg Simple Context 0 deg 0.5 deg 1 deg Contrast 80% 80% -80% -80% -80% 80% Methods Duration (sec) 1 0.5 2 0.1 ! The color appearance of an object under scotopic illuminating conditions varies depending on the context in which the object is viewed, irrespective of the photopically assigned color. Specifically, an object will appear bluish-green when viewed in isolation, but may appear red or orange when accompanied by a neighboring object with a higher scotopic luminance (Pokorny et al., 2006. Visual Neuroscience, 23, 525-530). Previous studies on relational scotopic color used free viewing in space and time and very large samples. We investigated the spatial and temporal stimulus conditions required to illicit relational hue percepts under scotopic conditions. No Context Simple Context Complex Context Spacing 1 0.5 1 0.5 0 0 −80 −40 40 80 Contrast Example Individual Data for Simple Context and 1 sec Duration Highlighted charts above reorganized to illustrate hue percept differences due to inducer spacing −80% −40% 40% 80% Observer YL No Context Contrast −80% −40% 40% 80% Observer SE No Context Spacing 1 0.5 0 −80% −40% 40% 80% Observer DC No Context Top right panel: Hue percepts averaged across observers. Each pie chart illustrates the distribution of hue percepts across 100 trials (10 observers x 10 repeats each) for each condition. Gray sections denote trials with reported achromatic percepts, which accounted for 41% of all trials (i.e., chromatic hue was reported in 5,901 out of 10K trials, or 59%). Colored sections correspond to the respective perceived hue. The average saturation for trials with reported perceived hue was 10.4%, ranging between 8.83-14.3% for conditions illustrated in the top right panel (averaged across observers). Due to the limited range of saturation ratings, saturation data are not presented. Each pie chart illustrates the distribution of hue percepts across 10 repeated trials for each condition. Colored sections correspond to the respective perceived hue, gray denotes trials with an achromatic hue percept. Mean Saturation 23.21% Range 16.5%-26.5% Mean Saturation 7.33% Range 5.62%-9.0% Mean Saturation 9.52% Range 7.5%-12.5% Support: NIH R01EY019651 D. Cao Conclusion n Relational hues were perceived under a variety of scotopic conditions. n There was no clear effect of duration on relational scotopic hue percepts. n Reddish-yellow hues were perceived more with less inducer spacing. n For individual observers, a change in contrast polarity generally shifted hue percepts between opponent combinations. n Complex context reduced the likelyhood of reddish-yellow percepts compared to simple context. 18% 5% 10%
Transcript of Hue perception under scotopic light levelsvpl.uic.edu/presentations/vss2011scotopic.pdf · 2016. 1....
Spacing = 0 deg Spacing = 0.5 deg Spacing = 1 deg
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−80% −40% 40% 80% −80% −40% 40% 80% −80% −40% 40% 80%Contrast
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Hue perception under scotopic light levelsSarah L. Elliott1 & Dingcai Cao1,2
1 Institute for Mind and Biology, University of Chicago, Chicago, IL, USA2 Section of Ophthalmology and Vision Science, University of Chicago, Chicago, IL, USA
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Results
A 1 deg test ring was viewed at a 7 deg retinal eccentricity on a CRT covered by neutral density �lters. The test luminance was approximately -2.6 log scotopic cd/m2 (-4 log photopic cd/m2) . The test ring was surrounded by either 2 (simple context - both equal luminance, either higher or lower than test) or 4 (complex context - 2 higher, 2 lower luminance than test) 1 deg inducing rings. Stimulus duration (4 temporal presentations), inducer spacing (3 conditions) and contrast (4 conditions) were varied for both simple and complex context. A hue scaling technique was used to measure perceived hue and saturation.
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The color appearance of an object under scotopic illuminating conditions varies depending on the context in which the object is viewed, irrespective of the photopically assigned color. Speci�cally, an object will appear bluish-green when viewed in isolation, but may appear red or orange when accompanied by a neighboring object with a higher scotopic luminance (Pokorny et al., 2006. Visual Neuroscience, 23, 525-530). Previous studies on relational scotopic color used free viewing in space and time and very large samples. We investigated the spatial and temporal stimulus conditions required to illicit relational hue percepts under scotopic conditions.
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Example Individual Data for Simple Context and 1 sec Duration
Highlighted charts above reorganized to illustrate hue percept differences due to inducer spacing
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Observer YL
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Observer SE
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Top right panel: Hue percepts averaged across observers. Each pie chart illustrates the distribution of hue percepts across 100 trials (10 observers x 10 repeats each) for each condition. Gray sections denote trials with reported achromatic percepts, which accounted for 41% of all trials (i.e., chromatic hue was reported in 5,901 out of 10K trials, or 59%). Colored sections correspond to the respective perceived hue.
The average saturation for trials with reported perceived hue was 10.4%, ranging between 8.83-14.3% for conditions illustrated in the top right panel (averaged across observers). Due to the limited range of saturation ratings, saturation data are not presented.
Each pie chart illustrates the distribution of hue percepts across 10 repeated trials for each condition. Colored sections correspond to the respective perceived hue, gray denotes trials with an achromatic hue percept.
Mean Saturation 23.21%Range 16.5%-26.5%
Mean Saturation 7.33%Range 5.62%-9.0%
Mean Saturation 9.52%Range 7.5%-12.5%
Support: NIH R01EY019651 D. CaoCon
clus
ion n Relational hues were perceived under a variety of scotopic conditions.
n There was no clear e�ect of duration on relational scotopic hue percepts.n Reddish-yellow hues were perceived more with less inducer spacing.n For individual observers, a change in contrast polarity generally shifted hue percepts between opponent combinations.n Complex context reduced the likelyhood of reddish-yellow percepts compared to simple context.
18% 5% 10%
