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Shahram Peyvandi, Alan Gilchrist; A New Approach to the Absorption of Photon Energy among Retinal Cells Provides the Key to Some Old Problems in Color Vision. Journal of Vision 2016;16(12):1150. doi: 10.1167/16.12.1150.
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© 2017 Association for Research in Vision and Ophthalmology.
The standard method of calculating cone response fails to capture the variability of absorbed energy among cells. Two identical cone cells of the same type exposed to the same uniform light absorb different amounts of energy. We have derived a distribution for the fractional number of cells absorbing different levels of energy and we find that this distribution implies a limit to the magnitude of chromatic induction. We studied chromatic induction using a small disk, approximately neutral (CCT of 2700 Kelvin), located within a homogenous background that filled the entire visual field. The surround was illuminated with red light of luminance 15 cd/m2. Subjects' task was to neutralize the induced color by nulling. Six surround saturation levels were used with both decremental and equiluminant targets. In agreement with Kirschmann's fourth law, we observed that as surround saturation increases, induction increases, but induction rate falls off, although, the form of the falloff is still not well understood. To analyze the extent to which red light was added to the target disk to make it appears neutral, the Bhattacharyya distance between bivariate distributions of chromaticities for the neutralized and white targets was calculated. We observed a residual amount of overlap between chromaticities of the neutralized and white targets at different surround saturations. This result indicates that the variation of energy distributed among cells stimulated by light from the target imposes a limit to the magnitude of induction. We suggest that a plausible mechanism for the effect is the distortion of target cells' energy distribution by the surround color stimulation, which results in altering the balance of photoreceptor signals toward the induced color. This observation, derived from statistical representation of energy distribution among cells, would not be possible with the conventional representation in which color is quantified by single values of cone responses.
Meeting abstract presented at VSS 2016
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