Optimum probabilistic processing in colour perception. II. Colour vision as template matching

1979 ◽  
Vol 205 (1159) ◽  
pp. 249-266 ◽  
Keyword(s):  
Template Matching ◽  
Colour Vision ◽  
Statistical Approach ◽  
Line Element ◽  
Colour Space ◽  
Spectral Parameters ◽  
Colour Perception ◽  
Wavelength Filter ◽  
Basic Constraint ◽  
Optimum Estimate

A statistical approach to account for psychophysical phenomena in human colour vision is presented. The central visual processor is viewed as an optimum recognizer of stochastic patterns supplied by the periphery. The processor makes an optimum estimate of the spectral parameters of the stimulus, given the wavelength filter characteristics of the periphery, the stochastic nature of the information and an internal template to which the external stimulus is matched. The estimate is constrained in ways inferred from empirical phenomena. Subjective brightness of mono­chromatic stimuli and related constant brightness manifolds in the colour space constitute the constraint for brightness estimation. Results analogous and in accord with those of earlier line element theories are obtained. The Bezold-Brücke hue shift constitutes the basic constraint for hue estimation. The hue estimate involves interrelation between the fields in the experiment. Similarities and differences both in basic conceptions and results introduced by the template matching notions are discussed.

scholarly journals Chromagen lenses and abnormal colour perception

2011 ◽  
Vol 70 (2) ◽  
Author(s):  
O. Matthew Oriowo ◽  
Abdullah Z Alotaibi
Keyword(s):  
Colour Vision ◽  
Contact Lenses ◽  
Individual Case ◽  
School Age Children ◽  
Colour Perception ◽  
Colour Vision Deficiency ◽  
Different Types ◽  
Wavelength Filter ◽  
Vision Defects ◽  
Case Basis

Background: The Chromagen lens system comprises of tinted spectacle or contact lenses, each with a specific colour wavelength filter which controls the spectra of the light entering the eye. This study investigated whether spectacle-mounted Chromagen lenses would enhance colour perception in individuals with abnormal colour vision.Methods: The Ishihara colour test was used to test for colour vision deficiency (CVD) and also to evaluate the effect of the Chromagen spectacle lens on colour perception in 13 subjects. An Oculus Anomaloscope was used to confirm and sub-classify the types of CVD. Subjects comprised of school age children from the Riyadh area in Saudi Arabia.Results: The distribution amongst the male participants comprised two subjects with protanomaly, two with protanopia, five with deuteranomaly, and two with deuteranopia. Amongst the two female participants, one subject showed deuteranomaly, and one showed protanomaly. Different types of Chromagen spectacle lenses displayed some levels of colour vision enhancement depending on type of CVD.Conclusion: The findings support the notion that chromagen lenses could enhance colour vision perception in some cases of red-green colour vision defects. Clients with CVD should be managed on an individual case basis. (S Afr Optom 2011 70(2) 69-74) 

Optimum probabilistic processing in colour perception. I. Colour discrimination

1979 ◽  
Vol 205 (1159) ◽  
pp. 229-247 ◽  
Keyword(s):  
Statistical Estimation ◽  
Decision Rules ◽  
Colour Space ◽  
Spectral Parameters ◽  
Colour Perception ◽  
Optimum Decision ◽  
Statistical Estimation Theory ◽  
Wavelength Discrimination ◽  
Geometrical Concepts ◽  
Element Theory

A comprehensive account of wavelength discrimination and colour satu­ration discrimination is given in terms of optimum probabilistic signal detection. The theory is a logical deduction from statistical estimation theory of the visual estimate of the spectral parameters of the stimulus. In place of geometrical concepts associated with colour-space geometry, stimulus discriminability is determined by optimum decision rules given by likelihood ratio tests on statistics that are postulated for the trichro­matic responses. The classical line element theory and its formulations are deduced to be discriminability measures between signals. The different mathematical forms of classical theory are shown to correspond to differ­ent statistical constraints.

Spectral Sensitivity of Photoreceptors and Colour Vision in the Solitary Bee, Osmia Rufa

1988 ◽  
Vol 136 (1) ◽  
pp. 35-52
Author(s):  
R. MENZEL ◽  
E. STEINMANN ◽  
J. DE SOUZA ◽  
W. BACKHAUS
Keyword(s):  
Spectral Sensitivity ◽  
Colour Vision ◽  
Three Dimensional ◽  
Just Noticeable Difference ◽  
Species Discrimination ◽  
Colour Space ◽  
Absorption Function ◽  
Perceptual Distance ◽  
Line Elements ◽  
Colour Signals

The spectral sensitivity of single photoreceptors of Osmia rufa was determined by a fast voltage-clamp technique. Three receptor types were found whose spectral sensitivity functions followed a rhodopsin-like photopigment absorption function with λmax values at 348nm (ultraviolet receptor), 436nm (blue receptor) and 572nm (green receptor). The λmax of the green receptor in Osmia rufa is shifted to much longer wavelengths compared with other insect species. Discrimination of colour signals was tested after training a bee at the entrance to its nest. The colour signals were filter discs (70 mm in diameter) with a hole (10 mm in diameter) in the centre and the bees quickly learned to use the coloured disc as a marker of the nest entrance. Tests were dual forced-choice tests with two coloured discs closely positioned next to each other. 94 different tests were each repeated 5–15 times and were performed after training to 12 different colour signals. A photoreceptor model was used to calculate the loci of the colour signals in a three-dimensional colour space and in a chromaticity diagram. The perceptual distance between the colour loci was calculated as line elements (minimum number of just noticeable difference, jnd-steps), which were based on the noiseproperties of the photoreceptors. The discrimination determined by the behavioural tests correlated very well with the jnd-steps. The correlation was better for the line elements in the colour plane than in the colour space. Osmia rufa was compared with the honeybee Apis mellifera and the stingless bee Melipona quadrifasciata. There is no difference in colour selection between Osmia and Apis, whereas Melipona discriminates less well in the violet-blue region. The model calculation was used to compare the chromaticity diagrams and the spectral discrimination functions of the three species. It is concluded that the receptor model used in this study predicts the discrimination behaviour of the three bee species very well. Therefore, comparative studies on colour vision in flowervisiting insects may be based on spectral measurements of the photoreceptors, and in many cases this reduces the extent of laborious behavioural studies.

scholarly journals How colour palettes in maps are re-coloured by daltonization methods

2019 ◽  
Vol 1 ◽  
pp. 1-2
Author(s):  
Anne Kristin Kvitle
Keyword(s):  
Colour Vision ◽  
Information Graphics ◽  
Male Population ◽  
Colour Perception ◽  
Female Population ◽  
Other Information ◽  
Map Design ◽  
Enhancement Method ◽  
Choropleth Map ◽  
Future Work

<p><strong>Abstract.</strong> The ability of identifying objects and elements based on colour is important in order to decode the information in a map or other information graphics. For this reason, the colours need to appear correct and be perceived in the desired and intended way. Map reading is reported as a challenging task for people with impaired colour vision. In reviews of the challenges of colour vision deficiencies (CVD) in everyday life (Cole, 2004), up to 60 % of the subjects in the studies reported problems in reading colour coded charts, slides and prints. Other studies (Carter and Silverstein, 2010) describes the difficulties to distinguish and identify coloured objects in weather, financial and other maps and charts.</p><p>Colour vision deficiencies are common, where congenital CVD affects about 8 % of the male population and 0.4 % of the female population. In addition, colour vision and colour perception may be affected by medical conditions or injury (acquired CVD) and situational conditions (situation induced CVD).</p><p>Reviews of visual usability and accessible map design conclude that few maps appear to have been designed with CVD users in mind (Cartwright, 2015) and that the design efforts or research of accessible colours palettes for CVD observers are mostly limited to thematic maps such as choropleths (Kvitle, 2018).</p><p>Daltonization methods are image processing methods to automatically enhance information in existing images. A common enhancement method is re-colouring, changing the colours in the original image to make be more distinguishable to the CVD observers. The daltonization method targets a specific type of CVD, and may also have been designed for specific applications (natural images, scientific images, information graphics etc). Therefore, the evaluation of the methods is often based on a limited set of test images. Using one specific map image as input will give very different results based on the daltonization methods.</p><p>The aim of the work is primarily to examine how the colour palettes in a map are altered by different daltonization methods. Second, the aim is to explore how different map types are influenced by the daltonization methods and to propose requirements and guidelines for test images for future work.</p><p> The set of test images in this work includes</p><ul><li>Information graphics (such as a tube map).</li><li>Choropleth map.</li><li>Reference map based on different map providers.</li></ul><p> To illustrate the visual differences, CVD simulation methods are applied on the original images and the daltonized versions of the images.</p>

For My Eyes Only

Secret Worlds ◽  
2021 ◽  
pp. 53-84
Author(s):  
Martin Stevens
Keyword(s):  
Visual Processing ◽  
Colour Vision ◽  
Green Light ◽  
Light Spectrum ◽  
Colour Perception ◽  
Mantis Shrimp ◽  
Uv Vision ◽  
Different Dimensions ◽  
Different Parts ◽  
Polarisation Vision

This chapter explores how vision is used by animals and the diversity in ways of seeing. It first details how colour vision works, focusing on the example of honeybees, which, like humans, are trichromatic and have good colour vision. Bees have a dedicated ultraviolet (UV) receptor, and then one for seeing shortwave (blue) and mediumwave (green) light. Other animals deviate more substantially, in that they have either more or fewer receptors used in colour vision, and hence different ‘dimensions’ of colour perception. The chapter then considers how jumping spiders use UV vision in identifying known or suitable prey species, as well as in mating. It also looks at polarisation vision in mantis shrimp. Mantis shrimp are bizarre in the number of receptors they have, each sensitive to different parts of the light spectrum. Finally, the chapter assesses how toads recognize prey from non-prey. The toad’s visual system acts as a ‘feature detector’ based on several stages of visual processing, producing a quick and appropriate response to a set of criteria that reliably encode objects of particular importance—in this case, food.

Colour Vision in Migraine: Selective Deficits for S-Cone Discriminations

Cephalalgia ◽  
2005 ◽  
Vol 25 (6) ◽  
pp. 412-423 ◽  
Author(s):  
AJ Shepherd
Keyword(s):  
Colour Vision ◽  
Visual Pathways ◽  
Control Groups ◽  
Colour Perception ◽  
Threshold Detection ◽  
The Third ◽  
And Control

Three studies are reported that explore colour perception in migraine. In each, sensitivity for colours detected selectively by the S-cones and the L- and M-cones was assessed separately. The first study assessed the discrimination of small colour differences using the Farnsworth-Munsell 100-hue test. The second assessed threshold detection for purple, yellow, red and green targets on five equiluminant background colours. The third examined supra-threshold colour scaling using two colour series, purple-yellow and red-green. Each study indicated that differences in colour perception between migraine and control groups were restricted to colours detected by the S-cones, there were no differences in performance for colours detected by the L- and M-cones. The results are discussed in terms of possible pathologies in the early visual pathways.

Highly Accurate Measurements of Human Colour Vision Parameters with Application to Diagnostics

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 111-111 ◽  
Author(s):  
A V Chistopolov
Keyword(s):  
Colour Vision ◽  
Measurement Accuracy ◽  
Wide Spectrum ◽  
Testing Procedure ◽  
Chromaticity Diagram ◽  
Colour Perception ◽  
Small Deviations ◽  
Standard Observer ◽  
Prolonged Testing ◽  
Normal Perception

A new method for measuring a wide spectrum of parameters describing a subject's colour vision is presented. It is based on a portable visual colorimeter, ‘Spectr-3M’, designed in our laboratory and has several useful features: (1) it enables testing over a wide area of the chromaticity diagram; (2) it allows the use of continuously changing colour stimuli; (3) the measurement accuracy is high; (4) the testing procedure is fast and comfortable, minimising the effects caused by prolonged testing and increasing the reliability of the data. Using this method we have revealed significant deviations from the CIE 1931 standard colorimetric observer in the colour perception of several subjects previously attested by the Rabkin and Ishihara charts as having normal perception. The data obtained by our method are more informative than results obtained with the Nagel anomaloscope, revealing not only general features of colour perception defects (as the anomaloscope), but allowing more detailed characterisation, including even small deviations from the CIE 1931 standard observer.

scholarly journals On negative after-images with pure spectral colours

1913 ◽  
Vol 86 (585) ◽  
pp. 117-118
Keyword(s):  
Colour Vision ◽  
Stray Light ◽  
Experimental Conditions ◽  
Colour Perception ◽  
Green Colour ◽  
Dark Room

In a paper “On Negative After-Images and Successive Contrast with Pure Spectral Colours,” by Mr. A. W. Porter, F. R. S., and Dr. F. W. Edridge-Green, the authors describe certain experiments, which they consider impossible of explanation on either the Hering or the Young-Helmholtz theory of colour vision. In justice to Thomas Young, it is only fair to point out a discrepancy between the title of the paper and the experimental conditions therein described, viz.: “The method adopted was as follows: In a dark room, in which, however, there was a certain amount of stray light , a horizontal spectrum, as pure as possible, was projected on a screen. A portion of the retina of one eye was then fatigued by rigidly gazing at a portion of another spectrum, isolated in the Edridge-Green colour-perception spectrometer. . . . After the fatiguing light had been viewed for about 20 seconds, the eye was turned to the screen, so that the after-image formed a band running right across the spectrum on the screen and occupying its centre.”

Atmospheric ozone concentration and the colour vision of insect pollinators

1999 ◽  
Vol 47 (5) ◽  
pp. 529 ◽  
Author(s):  
Adrian G. Dyer ◽  
Adrian G. Dyer
Keyword(s):  
Theoretical Model ◽  
Ozone Concentration ◽  
Colour Vision ◽  
Atmospheric Ozone ◽  
Large Reduction ◽  
Minimal Effect ◽  
Colour Space ◽  
Diffuse Illumination ◽  
Insect Pollinators

Using a theoretical model of honeybee colour vision, and considering direct and diffuse illumination conditions, it is shown that a large reduction in atmospheric ozone concentration would have a minimal effect on bee colour vision over the whole of their colour space.

Sign in / Sign up

Export Citation Format

Share Document