Search PubMed⌕ Search

Biomedical subjects

C R Ingling

Publications and source records attributed to C R Ingling.

At least 19 recordsLinked to original sources
PubMed1996

Chromatic content of spectral lights.

Using three novel formats, we compare four estimates of the spectral sensitivity of the opponent stage channels: a Linear Model, Jameson and Hurvich's [Journal of the Optical Society of America, 45, 546-552 (1955)] hue cancellation sensitivities, Gordon and Abramov's [Optical Society of America Technical Digest Series, 15, 12-15 (1987)] hue scaling, and hue matching. The three formats are: the spectrum locus in the opponent equiluminant plane, null lines in the CIE XYZ chart and response functions for unique hues. All sensitivities show departures from the Linear Model and from each other. Relative to the model, common features of all estimates are that violets are compressed; long-wavelength reds are amplified; the redness component of violet lights is greatly attenuated; and saturation of violet stimuli is underestimated.

Color Perception↗
PubMed1988

Spectral sensitivity for flicker and acuity criteria.

Different channels in the visual system mediate the detection of flicker and the detection of high spatial frequencies. The magnocellular channel is optimized for flicker detection, whereas the parvocellular channel is optimized for color vision and spatial resolution. The spectral sensitivity of the magnocellular (flicker) channel is obtained by combining cone inputs in the ratio R/G = 5/3; the spectral sensitivity of the parvocellular channel is obtained with the ratio R/G = 2/3. However, when the parvocellular channel is used for resolution, the sensitivity changes from R/G = 2/3 to R/G = 5/3. By hypothesis, this occurs because only parvocellular centers resolve high spatial frequencies and because parvocellular centers are distributed in the same ratio as cones feeding magnocellular cells.

Color Perception↗
PubMed1985

The spatiotemporal properties of the r-g X-cell channel.

Analysis of the simple-opponent r-g receptive field of the X-channel shows that it is tuned to both high and low temporal frequencies, high and low spatial frequencies, and that its spectral sensitivity is both chromatic and achromatic.

Animals↗
PubMed1985

Flicker photometry and achromatic-channel structure.

It is widely assumed that the near-perfect additivity of heterochromatic flicker photometry implies the existence of an achromatic channel in the visual system, which accurately sums R- and G-cone signals. For flicker photometry to be additive, the channel that detects the flicker stimulus need not add cone signals.

Color Perception↗
PubMed1983

The relationship between spectral sensitivity and spatial sensitivity for the primate r-g X-channel.

Which visual channel detects high spatial frequencies during careful fixation? Color vision models based on psychophysical data contradict electrophysiological results. According to electrophysiology, the channel which mediates foveal acuity originates in the small, tonic color-opponent r-g units of the X-cell pathway. However, psychophysical models assign acuity to the V lambda channel because when acuity is used as a criterion for equating luminosity it is additive. In all opponent-color models the r-g channel is subadditive and hence is excluded from mediating acuity. We show that the r-g channel adds cone signals for high spatial frequencies and subtracts them for low, and conclude that the major achromatic channel for human foveal vision originates within the r-g color-opponent channel. Quantitative analysis makes explicit the interaction between the spatial and spectral variables for the simple-opponent cells which predominate in primate foveal vision.

Color Perception↗
PubMed1983

Tonic-phasic-channel dichotomy and Crozier's law.

The constancy of the dynamic range in a luminance-discrimination task is known as Crozier's law; an old rule says that about half of a log unit spans the range from a low to a high frequency of seeing. For our conditions the slope of the psychometric function is steeper for short than for long test flashes; Crozier's law requires a different constant when temporal parameters change. This result is substantiated by an analysis of Massof's data [Vision Res. 21,995 (1981)] on the variation of the slope of psychometric curves for different wavelengths. The change in Crozier's constant between conditions may reflect the presence of more than one detection channel. If short test flashes are detected by phasic channels and long test flashes by both phasic and tonic channels, then our result implies a shorter dynamic range for phasic (Y-cell) than for tonic (X-cell) channels.

Computers↗
PubMed1983

Simple-opponent receptive fields are asymmetrical: G-cone centers predominate.

For quantitative models of color vision, the R-cone contribution to the r-g channel is less than half of the R-cone contribution to the V lambda channel. There is currently no explanation of how this different contribution of R cones to the two channels comes about. We propose an asymmetrical receptive-field arrangement to explain the difference in weighting. Because cones in receptive-field surrounds are weighted less than cones in centers, placing R cones predominantly in surrounds and G cones in centers provides a simple differential weighting mechanism. Electrophysiological and psychophysical evidence substantiates such an asymmetry of simple-opponent fields.

Animals↗