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.

Modelling the effects of inter-observer variation on colour rendition

2017 ◽  
Vol 51 (1) ◽  
pp. 37-54 ◽  
Author(s):  
MJ Murdoch ◽  
MD Fairchild
Keyword(s):  
Colour Vision ◽  
Spectral Characteristics ◽  
Observer Variation ◽  
Light Sources ◽  
Standard Observer ◽  
Natural Range ◽  
Normal Colour ◽  
Range Of Variation

The colour rendition characteristics of light sources are quantified with measures based on CIE standard observers, which are reasonable representations of population averages. However, even among people with normal colour vision, the natural range of variation in colour sensitivity means any individual may see something different than the standard observer. Modelling results quantify the effects of these inter-observer differences on colour rendition measures defined by IES TM-30-15. In general, inter-observer differences tend to be smaller for light sources with high colour fidelity values, and they are affected by spectral characteristics of different lighting technologies. The magnitude of variation in colour rendition measures, up to 5–10 units in IES TM-30-15 ( Rf, Rg), measures is compared with other sources of variability and ambiguity.

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.

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.”

scholarly journals Unusual Fundus Autofluorescence Appearance in a Patient with Hydroxychloroquine Retinal Toxicity

2015 ◽  
Vol 6 (2) ◽  
pp. 186-190 ◽  
Author(s):  
Sleiman Abou-Ltaif
Keyword(s):  
Cumulative Dose ◽  
Colour Vision ◽  
Fundus Autofluorescence ◽  
Retinal Toxicity ◽  
Night Vision ◽  
Central Vision ◽  
Colour Perception ◽  
History Of ◽  
Caucasian Female

Purpose: To report an unusual fundus autofluorescence aspect in a patient with suspected hydroxychloroquine retinal toxicity. Method: Case report of an unusual presentation of a patient treated for 9 consecutive years with a therapeutically recommended dose of hydroxychloroquine. Result: We report the case of a 53-year-old Caucasian female treated with 400 mg hydroxychloroquine for rheumatoid arthritis over 9 years, currently on methotrexate and folinic acid, who stopped treatment 3 years ago. The cumulative dose is estimated at 1.314 kg. She recently noticed a reduction of vision in both eyes to 0.34 logMAR, with colour vision problems and major distortion in central vision. Fundus autofluorescence revealed minimal foveal pigmentary changes and more pronounced changes in the retina elsewhere. Foveal changes were confirmed by optical coherence tomography in both eyes. The patient did not report any colour perception difficulties or night vision problems and has no family history of any eye condition. Her visual field tested by an optician was full, with some central changes. Conclusion: Retinal toxicity from hydroxychloroquine can present in a different aspect than the commonly known retinal toxicity, and it happens even after years of cessation of the drug. The role of cumulative dose in toxicity is supported in this paper.

scholarly journals Functional measurements of human ventral occipital cortex: retinotopy and colour

2002 ◽  
Vol 357 (1424) ◽  
pp. 963-973 ◽  
Author(s):  
Alex R. Wade ◽  
Alyssa A. Brewer ◽  
Jochem W. Rieger ◽  
Brian A. Wandell
Keyword(s):  
Colour Vision ◽  
Occipital Lobe ◽  
Occipital Cortex ◽  
Ventral Surface ◽  
Spatial Density ◽  
Colour Perception ◽  
Field Representation ◽  
Density Peaks ◽  
Definition Of ◽  
Increased Activity

Human colour vision originates in the cone photoreceptors, whose spatial density peaks in the fovea and declines rapidly into the periphery. For this reason, one expects to find a large representation of the cone–rich fovea in those cortical locations that support colour perception. Human occipital cortex contains several distinct foveal representations including at least two that extend onto the ventral surface: a region thought to be critical for colour vision. To learn more about these ventral signals, we used functional magnetic resonance imaging to identify visual field maps and colour responsivity on the ventral surface. We found a visual map of the complete contralateral hemifield in a 4 cm 2 region adjacent to ventral V3; the foveal representation of this map is confluent with that of areas V1/2/3. Additionally, a distinct foveal representation is present on the ventral surface situated 3–5 cm anterior from the confluent V1/2/3 foveal representations. This organization is not consistent with the definition of area V8, which assumes the presence of a quarter field representation adjacent to V3v. Comparisons of responses to luminance–matched coloured and achromatic patterns show increased activity to the coloured stimuli beginning in area V1 and extending through the new hemifield representation and further anterior in the ventral occipital lobe.

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 Democritus’ Theory of Colour

Rhizomata ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 269-305
Author(s):  
Kelli Rudolph
Keyword(s):  
Colour Vision ◽  
Colour Perception ◽  
Dynamic Interplay

AbstractI argue that Democritus presents a theory of colour in which the predominance of atomic shapes and microstructural arrangements are necessary but not sufficient for colour vision. Focusing primarily on Democritus’ basic colours, I analyse his microstructural account, providing a new analysis of the natural and technological underpinnings of his method of explanation. I argue that the notion of predominance allows Democritus to account for both the variation and the repeatable correspondence of colour perception by setting limits on possible microstructures. This account, however, is complicated by the evidence for a Democritean theory of colour transformation and distorted vision, which arise from a dynamic interplay of features at the level of microstructures and at the level of perception.

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