The Cost of Trichromacy for Spatial Vision

Williams, David R.; Sekiguchi, Nobutoshi; Haake, William; Brainard, David H.; Packer, Orin S.

doi:10.1007/978-1-4615-3718-2_2

Cited by 36 publications

(44 citation statements)

References 29 publications

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“…Moreover, it has been found experimentally that trichromacy does not influence spatial acuity [2]. The ability of a trichromatic human observer to detect achromatic gratings is similar to those theoretically given by a retina composed of only one type of photoreceptor.…”

Section: Introductionmentioning

confidence: 63%

Linear demosaicing inspired by the human visual system

Alleysson

Süsstrunk

Hérault

2005

IEEE Trans. on Image Process.

295

281

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Abstract-There is an analogy between single-chip color cameras and the human visual system in that these two systems acquire only one limited wavelength sensitivity band per spatial location. We have exploited this analogy, defining a model that characterizes a one-color per spatial position image as a coding into luminance and chrominance of the corresponding three-colors per spatial position image. Luminance is defined with full spatial resolution while chrominance contains sub-sampled opponent colors. Moreover, luminance and chrominance follow a particular arrangement in the Fourier domain, allowing for demosaicing by spatial frequency filtering. This model shows that visual artifacts after demosaicing are due to aliasing between luminance and chrominance and could be solved using a pre-processing filter. This approach also gives new insights for the representation of single-color pe r spatial location images and enables formal and controllable procedures to design demosaicing algorithms that perform well compared to concurrent approaches, as demonstrated by experiments.

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Section: Introductionmentioning

confidence: 63%

Linear demosaicing inspired by the human visual system

Alleysson

Süsstrunk

Hérault

2005

IEEE Trans. on Image Process.

295

281

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“…The irregularity of L-and M-cone arrangement exacerbates the confounding of spatial and chromatic information on small scales, leading to errors in color appearance for fine spatial patterns (Williams et al, 1991). One example is the Brewster's colors phenomenon, in which irregular splotches of pastel colors are seen when viewing fine periodic black and white patterns (Brewster, 1832).…”

Section: Implications Of L/m Cone Arrangement For Visionmentioning

confidence: 99%

Organization of the Human Trichromatic Cone Mosaic

Hofer¹,

Carroll²,

Neitz³

et al. 2005

J. Neurosci.

414

311

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Using high-resolution adaptive-optics imaging combined with retinal densitometry, we characterized the arrangement of short-(S), middle-(M), and long-(L) wavelength-sensitive cones in eight human foveal mosaics. As suggested by previous studies, we found males with normal color vision that varied in the ratio of L to M cones (from 1.1:1 to 16.5:1). We also found a protan carrier with an even more extreme L:M ratio (0.37:1). All subjects had nearly identical S-cone densities, indicating independence of the developmental mechanism that governs the relative numerosity of L/M and S cones. L:M cone ratio estimates were correlated highly with those obtained in the same eyes using the flicker photometric electroretinogram (ERG), although the comparison indicates that the signal from each M cone makes a larger contribution to the ERG than each L cone. Although all subjects had highly disordered arrangements of L and M cones, three subjects showed evidence for departures from a strictly random rule for assigning the L and M cone photopigments. In two retinas, these departures corresponded to local clumping of cones of like type. In a third retina, the L:M cone ratio differed significantly at two retinal locations on opposite sides of the fovea. These results suggest that the assignment of L and M pigment, although highly irregular, is not a completely random process. Surprisingly, in the protan carrier, in which X-chromosome inactivation would favor L-or M-cone clumping, there was no evidence of clumping, perhaps as a result of cone migration during foveal development.

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“…Williams et al 36 argued that the colors perceived from fine, periodic, achromatic patterns, originally described by Brewster." can be explained by chromatic aliasing by the Land M cones.…”

Section: Nsmentioning

confidence: 99%

Aberration-free measurements of the visibility of isoluminant gratings

1993

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We developed a new apparatus and psychophysical technique to extend isoluminant contrast-sensitivity measurements to high spatial frequencies. The apparatus consists of two identical laser interferometers that are designed to produce phase-locked two-color interference fringes on the retina without the influence of diffraction and most aberrations in the eye. However, even with interferometry, transverse chromatic aberration of the eye can produce a wavelength-dependent phase shift in the interference fringes, which can be exaggerated by head movements. To reduce the effect of head movements, isoluminant red and green interference fringes of equal spatial frequency and orientation were drifted slowly in opposite directions to guarantee a purely isochromatic (in phase) and a purely isoluminant (out of phase) stimulus during each cycle of stimulus presentation. With this technique we found that observers could resolve red and green stripes at spatial frequencies higher than 20 cycles per degree (c/deg) (20-27 c/deg), substantially higher than has previously been reported. This places a lower bound on the sampling density of neurons that mediate color vision. At all spatial frequencies, even those above the isoluminant resolution limit, a relative phase of the red and the green components could be found that obliterated the appearance of luminance modulation at the fringe frequency. Above the resolution limit, red-green-isoluminant interference fringes are seen as spatial noise, which may be chromatic aliasing caused by spatial sampling at some stage in the chromatic pathway.

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The Cost of Trichromacy for Spatial Vision

Cited by 36 publications

References 29 publications

Linear demosaicing inspired by the human visual system

Linear demosaicing inspired by the human visual system

Organization of the Human Trichromatic Cone Mosaic

Aberration-free measurements of the visibility of isoluminant gratings

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