Color Vision

Mollon, J. D.

doi:10.1146/annurev.ps.33.020182.000353

Cited by 166 publications

(69 citation statements)

References 65 publications

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“…In addition, ON plus OFF activities are added, without lling-in, to the lled-in ON-minus-OFF activities to provide a baseline that is sensitive t o b a c kground luminance, and the lled-in OFFminus-ON activities are divided from them. These di erence (ON{OFF) and sum (ON+OFF) operations are reminiscent of the L-M color computation and L+M luminance computation that takes place between long (L) and medium (M) wavelength retinal cone channels (Mollon and Sharpe, 1983).…”

Section: Methods and Resultsmentioning

confidence: 99%

Synthetic aperture radar processing by a multiple scale neural system for boundary and surface representation

1995

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A neural network model of boundary segmentation and surface representation is developed to process images containing range data gathered by a s y n thetic aperture radar (SAR) sensor. The boundary and surface processing are accomplished by an improved Boundary Contour System (BCS) and Feature Contour System (FCS), respectively, t h a t h a ve been derived from analyses of perceptual and neurobiological data. BCS/FCS processing makes structures such as motor vehicles, roads, and buildings more salient and interpretable to human observers than they are in the original imagery. Early processing by ON cells and OFF cells emb e d d e d i n s h unting centersurround network models preprocessing by lateral geniculate nucleus (LGN). Such preprocessing compensates for illumination gradients, normalizes input dynamic range, and extracts local ratio contrasts. ON cell and OFF cell outputs are combined in the BCS to de ne oriented lters that model cortical simple cells. Pooling ON and OFF outputs at simple cells overcomes complementary processing de ciencies of each c e l l t ype along concave and convex contours, and enhances simple cell sensitivity to image edges. Oriented lter outputs are recti ed and outputs sensitive to opposite contrast polarities are pooled to de ne complex cells. The complex cells output to stages of shortrange spatial competition (or endstopping) and orientational competition among hypercomplex cells. Hypercomplex cells activate long range cooperative bipole cells that begin to group image boundaries. Nonlinear feedback b e t ween bipole cells and hypercomplex cells segments image regions by cooperatively completing and regularizing the most favored boundaries while suppressing image noise and weaker boundary groupings. Boundary segmentation is performed by three copies of the BCS at small, medium, and large lter scales, whose subsequent i n teraction distances covary with the size of the lter. Filling-in of multiple surface representations occurs within the FCS at each scale via a boundary-gated di usion process. Di usion is activated by the normalized LGN ON and OFF outputs within ON and OFF lling-in domains. Di usion is restricted to the regions de ned by gating signals from the corresponding BCS boundary segmentation. The lled-in opponent O N and OFF signals are subtracted to form double opponent surface representations. These surface representations are shown by a n y of three methods to be sensitive to both image ratio contrasts and background luminance. The three scales of surface representation are then added to yield a nal multiple-scale output. The BCS and FCS are shown to perform favorably in comparison to several other techniques for speckle removal.

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Section: Methods and Resultsmentioning

confidence: 99%

Synthetic aperture radar processing by a multiple scale neural system for boundary and surface representation

1995

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“…One is that some adaptation of the visual system might result from learned characteristics of the environment because different observers experience different 'visual diets' (Mollon, 1982;Webster & Mollon, 1997). However, the different visual environments between our two languages with similar color terms would rule out the possibility.…”

Section: Color Categories 38mentioning

confidence: 99%

Color categories: Evidence for the cultural relativity hypothesis

Roberson

Davidoff

Davies

et al. 2005

Cognitive Psychology

300

255

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The question of whether language affects our categorization of perceptual continua is of particular interest for the domain of color where constraints on categorization have been proposed both within the visual system and in the visual environment. Recent research Roberson et al., in press) found substantial evidence of cognitive color differences between different language communities, but concerns remained as to how representative might be a tiny, extremely remote community. The present study replicates and extends previous findings using additional paradigms among a larger community in a different visual environment. Adult semi-nomadic tribesmen in Southern Africa carried out similarity judgments, short-term memory and long-term learning tasks. They showed different cognitive organization of color to both English and another language with the five color terms. Moreover, Categorical Perception effects were found to differ even between languages with broadly similar color categories. The results provide further evidence of the tight relationship between language and cognition.

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“…While it can not be said that there is general agreement among authorities as to the most valid operational definition of human long-and medium-wave sensitive cone action spectra, there are strong converging lines of evidence from experiments as diverse as psychophysical observations on short-wave cone monochromacy (Alpern, Lee & Spivey, 1965;Alpern, Lee, Maaseidvaag & Miller, 1971;Alpern, 1974), on transient changes in backgrounds (Stiles, 1949;Mollon & Polden, 1975Stiles, 1978; Augenstein & Pugh, 1977;Pugh & Mollon, 1979;Mollon, 1982), on two colour threshold vs. wave-length curves (Wald, 1964) and from in situ microspectrophotometry of the visual pigments of individual short-wave sensitive cones (Bowmaker & Dartnall, 1980) all pointing to H3(u) as the most valid operational definition available for the action spectrum of human short-wave sensitive cones. Before reaching such a striking conclusion alternative interpretations of the contradiction illustrated in Fig.…”

Section: Introductionmentioning

confidence: 99%

The dependence of the colour and brightness of a monochromatic light upon its angle of incidence on the retina.

Alpern¹,

Kono²,

Tamaki³

1983

The Journal of Physiology

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SUMMARY1. The changes in brightness and colour of a monochromatic test light as its angle of incidence on the retina was changed from normal (pupil centre traverse) to oblique (3 5 mm temporal pupil traverse), was measured by matching it with three normally incident primaries. Results on two normal trichromats were generally in accord with published data on the Stiles-Crawford intensity and colour effects.2. One observer was also the subject of the preceding paper (Alpern & Kitahara, 1983) in which the field sensitivities of his foveali1(,u) (j = 3, 4, 5) mechanisms for normally, and obliquely, incident backgrounds were reported. For normal incidence, the colour matching functions are in rough accord with expectation if the action spectra of the three cone mechanisms, which provide the photoreceptor basis for his trichromacy, were the same Hi mechanisms for normal incidence.3. A unified theory is developed for both Stiles-Crawford intensity and colour effects, assuming that the same visual pigments in the same set of univariantly signalling cones absorbs both the normal incident primaries and the obliquely incident test. Given no free parameters for curve fitting, the Stiles-Crawford intensity effect data are in reasonable agreement with the theory if the photoreceptor basis of these matches were the normally and obliquely incident II(,u) mechanisms.4. The Stiles-Crawford colour effect data contradict the expectations ofthe unified theory applied with these same Hl1(l) mechanisms. Either H3,() is not a valid operational definition ofthe action spectrum ofhis short-wave sensitive photoreceptors or at least one assumption of the unified theory is false.

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Color Vision

Cited by 166 publications

References 65 publications

Synthetic aperture radar processing by a multiple scale neural system for boundary and surface representation

Synthetic aperture radar processing by a multiple scale neural system for boundary and surface representation

Color categories: Evidence for the cultural relativity hypothesis

The dependence of the colour and brightness of a monochromatic light upon its angle of incidence on the retina.

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