Theory Of Color Vision Research Articles

Adolf Fick (1829-1901), physiologist: a heritage for anesthesiology and critical care medicine.

Adolf Fick (1829-1901), physiologist: a heritage for anesthesiology and critical care medicine.

JOHN ZACHARY YOUNG, F.R.S., Hon. F.B.A., M.A. (1907–1997)

John Zachary Young, universally known as JZ, was born in Bristol on 18 March 1907 and died on 4 July 1997. The Zachary in his name was said to be of Cornish origin. His ancestor Thomas Young achieved fame through his modulus and through the Young–Helmholtz theory of colour vision. JZ was educated at Marlborough, which school also produced another notable scientist, student of and early collaborator with JZ, Peter Medawar. Having acquired an interest in zoology at school, JZ read zoology at Magdalen College, Oxford, and then obtained a scholarship to work at the Zoological Section in Naples. There he began to investigate the autonomic innervation of the gut of fish. While in Naples he rediscovered the giant axons of the squid but, unlike L. W. Williams in 1909, he immediately recognised their importance. His observations led to the fundamental studies on the generation of the membrane potential and conduction of the action potential of axons by Hodgkin and Huxley. During his time in Naples before the War, JZ began his lifelong interest in the brain and behaviour of cephalopods.

Demonstrations of Color Perception and the Importance of Contours

A series of easily and inexpensively produced demonstrations provides examples of color perception after receptor cells have adapted to a stimulus. Visual performance under these conditions reveals phenomena that theories of color vision must explain. Students report their impressions of visual stimuli, and a discussion of trichromatic and opponent-process theories follows. These phenomena generate a second series of demonstrations showing the importance of contour information for perception.

Colour Perception 1978–1997

In the past twenty years, the spectral sensitivities of the three types of cone have been established with some certainty: direct measurements by microspectrophotometry and electrophysiology are in fair agreement with psychophysical estimates. Particularly significant was the publication of DNA sequences for the four opsins of the human eye, by Jeremy Nathans and colleagues in 1986. This work was soon to transform the understanding of retinitis pigmentosa and other retinal dystrophies, and it has given many insights into the evolution of colour vision; but, curiously, the explanations of dichromacy and anomalous trichromacy have not proved as straightforward as we all expected in 1986. What is clear, however, is that normal colour vision exhibits a genetic polymorphism: much of the intersubject variance in colour matches can be traced to differences in the amino-acid sequence of the opsins for the long-wave and middle-wave cone pigments. The last two decades have seen a major change in the status of opponent processes. In the 1970s it was still common for professors to tell undergraduates that the Young - Helmholtz theory of colour vision held at the receptor level and the Hering theory at the level of the retinal ganglion cells. It is now clear that the chromatically antagonistic processes revealed electrophysiologically and psychophysically in the early visual system do not correspond to the red - green and yellow - blue processes that Hering postulated on the basis of phenomenological observations. The existence of four unique hues is today one of the unexplained mysteries of colour science. In one salient respect, research in colour vision has been changed by instrumental advances. Computer-controlled monitors (though offering splendid pitfalls to the unwary) have allowed the study of spatially and temporally complex chromatic displays, notably in the field of colour constancy. Most recently there has been interest in the chromatic statistics of natural scenes: how well is the visual system matched to the statistics of the world and can it adapt to the gamut of chromaticities present in a given scene?

Constraints on the definitions of “unique hues” and “opponent channels”

Zone theories of color vision transform cone sensitivities to channel sensitivities before transmitting these signals to the brain. The concepts of “unique hue” and “color opponency” are fundamental to an understanding of this transformation. Saunders & van Brakel question the objectivity of these concepts. Statements in their target article indicate that the reason for this questioning stems from a failure to appreciate the constraints inherent in the definitions of these concepts.

Quantitative analysis of multichromatic moiré effects in the superposition of coloured periodic layers

In the present article we give a full quantitative analysis of the multichromatic moiré effects in the superposition of coloured periodic layers, which is based both on the Fourier theory and on the theory of colorimetry and colour vision. This is done by introducing both into the image domain and into the Fourier frequency domain a new dimension λ, representing the visible light wavelengths. In the image domain we represent each layer by the chromatic reflectance (or transmittance) function r(x, y; λ), which is a generalization of the reflectance (or transmittance) function r(x,y) in the monochromatic case. Consequently, in the Fourier spectral domain each impulse amplitude becomes a function of λ. All the results previously obtained by our Fourier-based approach in the monochromatic case remain valid in the multichromatic case, too, for every wavelength λ separately. This enables us to find, for every point (x,y) of any given moiré, the full colour spectrum {r(x,y; λ) | 380 ≤ λ ≤ 750} which expresses the visible colour at the point (x,y) of the moiré in question. We illustrate the discussion by several multichromatic superpositions, some of which showing very spectacular, colourful moiré effects.

Quantitative analysis of multichromatic moire effects in the superposition of coloured periodic layers

In the present article we give a full quantitative analysis of the multichromatic moire effects in the superposition of coloured periodic layers, which is based both on the Fourier theory and on the theory of colorimetry and colour vision. This is done by introducing both into the image domain and into the Fourier frequency domain a new dimension λ, representing the visible light wavelengths. In the image domain we represent each layer by the chromatic reflectance (or transmittance) function r(x,y;λ), which is a generalization of the reflectance (or transmittance) function r(x,y) in the monochromatic case. Consequently, in the Fourier spectral domain each impulse amplitude becomes a function of λ. All the results previously obtained by our Fourier-based approach in the monochromatic case remain valid in the multichromatic case, too, for every wavelength λ separately. This enables us to find, for every point (x,y) of any given moire, the full colour spectrum {r(x,y;λ)|380lλl750} which expresses the visible colour at the point (x,y) of the moire in question. We illustrate the discussion by several multichromatic superpositions, some of which showing very spectacular, colourful moire effects

Visual decomposition of colour through motion extrapolation.

The perception of yellow has played a central role in distinguishing two main theories of colour vision. Hering proposed that yellow results from the activation of a distinct retinal-neural mechanism, whereas according to the Young-Helmholtz-Maxwell view, yellow results from the combined activation of red and green cone mechanisms. When red and green images are presented separately to corresponding retinal locations in the two eyes, the resulting sensation is yellow. As the pathways from the two eyes do not converge until the cortex, this suggests that yellow can indeed arise from the central combining of separate red and green channels. I now show that the reverse process can also occur; the visual system can decompose a 'yellow' stimulus into its constituent red and green components. A 'yellow' stimulus was created by optically superimposing a flashed red line onto a moving green bar. If the bar is visible only briefly, the flashed line appears yellow. If the trajectory of the green bar is exposed for sufficient time, however, the line is incorrectly perceived to trail the bar, and appears red. Motion processing occurs in the cortex rather than the retina in primates, and so the ability of motion cues to affect the perception of colour is consistent with the Young-Helmholtz-Maxwell notion of a 'central synthesis' of yellow.

Perception Laboratory: A Computer Program to Demonstrate Perceptual Phenomena

I developed an interactive computer program that allows one to demonstrate and experiment with various phenomena in visual perception using IBM-compatible computers. The program contains modules for demonstrating the color afterimage, the cafe illusion, additive color mixing and the opponent-process theory of color vision, the glowing axes illusion, the Hermann grid, the McCollough effect, the motion aftereffect, the neon illusion, and simultaneous contrast. The user has considerable control over the stimuli making up the image and can manipulate the variables that contribute to the perception of the effect. The program can be used far classroom demonstrations and student laboratory projects.

A Model of Color Vision Based on Cortical Reentry

It is known that the perceived color of an object depends on the context in which it is viewed, its reflectance properties and the spectral distribution of the illuminating light. What is not known, however, is how the visual system functions so that color percepts depend upon the integration of local and contextual cues. While phenomenological theories of color vision exist, robust neurally based theories consistent with psychophysical observations are sparse. In the present study we develop such a theory and establish its self-consistency by computer simulations of cerebral cortical areas involved in color perception. The simulations test the hypothesis that long-range reciprocal connections within and between cortical areas mediate a dynamic process of reentry that integrates contextual cues into the color percept. When stimuli similar to those used in psychophysical testing of contextual influence were used, firing patterns consistent with psychophysical data on color constancy and color induction in humans were observed. Selective disruption of reciprocal inter- or intra-areal connections reduced the correspondence between the model's responses and the psychophysical data. The findings are consistent with the proposal that reentrant interactions within and between cortical areas provide a major basis for the context-sensitive aspects of color vision.

Colors of maximal saturation.

The spectrum locus on the CIE Chromaticity Diagram represents monochromatic stimuli which have been exposed to a dark adapted fovea. Some of these colors can be made to appear more saturated by chromatic adaptation. The colors both inside the spectrum locus and the supersaturated colors outside are bounded by a four-sided boundary line which constitutes the locus of colors of maximal saturation. An attempt has been made to show how this quadrilateral is related to the fundamental colors and to a zone theory of color vision.

Orphics: Computer Graphics and the Feasibility of a Preferred Color Order

AbstractBecause color has lost its permanent form in certain media such as computer displays, there is a need for some overriding organizational principle. In earlier work on orphics, this author has discussed some ideas and techniques for the fluid articulation of color in space and time without relying on a preferred color order. In this article the possibility of defining a sequence of colors arranged in a unique order, that is, general enough to serve as a tuning for the composition of color in space and time, is discussed. to gain as wide a perspective as possible, color vision theories and their relevance are discussed, as well as the structural compatibilities between color orders and the well‐tempered musical scale. Finally the works of two artists, Morgan Russell and Robert Delaunay, are examined.

Les couleurs complémentaires : un nouveau paradigme/Complementary colours: a new paradigm

SUMMARY. — The concept of complementary colours, discovered at the beginning of the nineteenth century, spread quickly, coming to play a foremost role as a paradigm for the scientific theories of colour vision as well as the theories of chromatic harmonies. Current developments in both fields still depend on this concept. This paper aims to throw light on the history and the implications of this concept during the first half of the last century, from the joint perspectives of the science of colour vision and aesthetics.

The Plasticity of Categories: The Case of Colour

Probably colour is the best worked-out example of allegedly neurophysiologically innate response categories determining percepts and percepts determining concepts, and hence biology fixing the basic categories implicit in the use of language. In this paper I argue against this view and I take C. L. Hardin's Color for Philosophers [1988] as my main target. I start by undermining the view that four unique hues stand apart from all other colour shades (Section 2) and the confidence that the solar spectrum is naturally divided into four categories (Section 3). For such categories to be truly universal, they have to be true for all peoples and in Section 4 I show that Berlin and Kay's [1969] widely quoted theory of basic colour categories is not sufficiently supported to lend it any credibility. Having disposed of the view that inspection of language or ‘pure’ perception unveils the universal colour categories. I turn to neurophysiological and psychophysical theories of colour vision to see whether they provide a more solid basis for deciding what the innate response categories are. In Section 5 I show that Hardin's account of the opponent-process theory neither supports his view that ‘colour-coding’takes place early in the visual neural pathway, nor his view that knowledge of colour vision science will help us solve many philosophical mysteries about colour. In Section 6 I give a more detailed review of what is known today about the neurophysiology of colour vision and I show that there's nothing in the brain which could be called a colour module, let alone a module with homunculi for particular basic colour categories. In Section 7 I show that psychophysical models do not support such rigid constraints on category formation either. Hence (Section 8), at least in the case of colour, current science supports a plasticity in the formation of categories that goes far beyond the requirements of those naturalistic philosophers who would like to ground primitive concepts in biology

Modern Quantum Theory of Color Vision and Statistical Colorimetry, Their Role and Influence on Changing Fundamental Assumptions of the Color Theory and Color Imaging Practice

Modern Quantum Theory of Color Vision and Statistical Colorimetry, Their Role and Influence on Changing Fundamental Assumptions of the Color Theory and Color Imaging Practice

The resonator theory of colour vision

The resonator theory claims that light scattering by the melanin granules of the retinal pigment epithelium causes light to be reflected back through the outer segment of the cones, in a direction opposite that of the incident light. These two opposite directed wave motions may produce standing waves inside the cone outer segment, which then acts as a resonating cavity for light waves. The wavelength specificity of the single cone is determined by the length and the diameter of the cone outer segment. The variation of the length and the diameter of the cone outer segments throughout the retina is then the basis of colour discrimination.

The Charles F. Prentice Award Lecture 1990: Specific Tests and Specific Blindnesses: Keys, Locks, and Parallel Processing

Classical color vision theory incorporates the concepts of hard-wired parallel independent processing and of hard-wired opponent-processing. These two powerful concepts can be applied more generally in visual psychophysics. The concept of parallel independent processing can help to understand two extremes of visual performance: disordered vision in patients and the extraordinary visual abilities of athletes and aviators. Three illustrations of this thesis are discussed. First, evidence for dissociations of spatial vision for low-contrast and high-contrast objects. Second, evidence that a binocular system for motion in depth runs in parallel with the classical disparity-driven binocular system for relative position in depth. Third, evidence that a visual system for motion-defined form parallels the well known system for contrast-defined form. However, in principle these two concepts have limited value because they do not incorporate the possibility that the functional organization of the visual pathway could be modified by descending task-dependent signals.

On a Possible Contribution to the Colour Sense by the Blur Circles on the Human Retina Caused by Chromatic Aberration

Theories of colour vision at the receptor and neurological level, while probably sound, could be made more plausible by the existence of the system processing colour cues available in the retina. One such cue could be chromatic aberration. Using an anomaloscope colour perception was adversely affected by the absence of chromatic aberration. Two groups of 16 subjects provided data.

Color vision model of macLeod and Boynton

AbstractMacLeod and Boynton started off with the assumption that the fundamental blue falls on the x' axis of Judd's 1951 chromaticity diagram. This leads to a constant luminance diagram in which the lines that converge at the fundamental blue in Judd's diagram are parallel. MacLeod and Boynton tried to solve this problem by a slight change in one of the constants in the transformation equations. It turns out that what this does is to shift the position of the alychne on Judd's diagram so that it does not coincide with the x' axis. The blue fundamental no longer lies on the alychne. This makes it possible to derive a constant luminance chromaticity diagram in which the fundamental blue falls at one of the corners. After having created this new diagram, they used it to formulate a theory of color vision in which the blue cones contribute nothing to luminance. This procedure needs to be understood because it can be used to convert any theory of color vision in which all three cones contribute to luminance to one in which only two contribute to luminance. This has nothing to do with having the blue fundamental fall on the x' axis. A more serious problem is that Judd has made an error in his assessment of the luminosity coefficients and the concepts of MacLeod and Boynton need to be reformulated in terms of the CIE 1931 chromaticity diagram.

Review of dichoptic color mixing.

Dichoptic color mixing has been a controversial issue for nearly two centuries. The first dispute arose from the fact that dichoptic color mixtures occur only under certain conditions. A later controversy arose over the implications of dichoptic color mixtures to color vision theories. The present consensus is that dichoptic color mixtures occur under conditions which apparently minimize chromatic differences between the two monocular impressions. However, dichoptic mixtures do not match the corresponding monoptic mixtures. Dichoptic mixtures appear dimmer, and if a green light is mixed with either a red or violet light, then the dichoptic mixture appears greener relative to the monoptic mixture.