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Sergio Nascimento, Joo Linhares, Ruben Pastilha, Jorge Santos, Vasco de Almeida; Perceived chromatic diversity in dichromacy benefits from the color distributions of natural scenes . Journal of Vision 2016;16(12):638. doi: 10.1167/16.12.638.
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© ARVO (1962-2015); The Authors (2016-present)
Inherited color vision deficiencies impair color discrimination and therefore impoverish the chromatic diversity perceived in natural scenes. For dichromacy, estimates based on hyperspectral imaging data from natural scenes and assuming Brettel's perceptual model, suggest a reduction in the number of perceived colors of about 93%. These estimates, however, do not take into account the actual distributions of colors in the scenes. Pairs of colors confused by dichromats may be rare and thus have small impact on perceived chromatic diversity. The purpose of this work was to estimate, empirically, how dichromacy impairs discrimination of pairs of colors in natural scenes. The stimulus for the experiment was a scene made of 3D objects painted with matte white paint. The scene subtended 10 deg and was set inside a light booth illuminated by a spectrally tunable light source based on the Digital Light Processor technology (OL 490 Agile Light Source, Gooch & Housego). The spectral composition of the light source could be tuned very fast with a spectral resolution of 20 nm using in-house software. In each trial of the experiment the observer first adapted for 1 s to the white standard illuminant E. Then, two spectra drawn randomly from hyperspectral data from one of four natural scenes, illuminated in succession the booth interior for 1 s each, with a dark ISI of the same duration. The observers had to indicate whether the spectra were the same or different. Four color normal observers and two dichromats carried out the experiment. It was found that the number of pairs that could be discriminated by dichromats was about 50% of those discriminated by normals, a fraction much higher than anticipated from estimates of discernible colors. This result suggest that the color distributions of natural scenes benefit the color vision of dichromats.
Meeting abstract presented at VSS 2016
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