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Topic: Colour vision


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  Vision and Colour
Most of vision takes place in the brain, and this begins in the retina, where the signals from neighbouring receivers are compared and a coded message dispatched on the optic nerves to the occipital cortex, behind the ears, where the information is formatted and made available to the processing activities of the brain.
Colour was associated with the refrangibility of the rays, dependent on the particle velocity.
He says that colour means pigments to an artist, an internal perception to a psychologist, the response of a neural system to a physiologist, an aspect of radiant energy to a physicist, and a property of objects and lights to the man in the street.
www.du.edu /~jcalvert/optics/colour.htm   (10652 words)

  
 HON: Vision and Eyecare FAQ: section7
Colour vision defects are classified via the number of primary spectral colours which an individual requires to match any other spectral colour.
Colour defective vision is inherited as a sex-linked recessive characteristic.
Acquired colour vision defects are generally asymmetrical in the two eyes, eg affecting red-green as well as yellow-blue, while also there may be other defects of visual function ( visual field defects).
www.hon.ch /Library/Theme/VisionFaq/section7.html   (323 words)

  
 Anomalous Colour Vision
This, besides being unfair, shows that the commonest varieties of colour blindness are congenital, due to genetic differences in the sex-determining Y chromosome (where some genes are not duplicated), and that colour blindness is a recessive characteristic, like haemophilia.
Colour blindness can also be the result of disease or poisoning, where it has no genetic basis, or due to other faults than those of the visual proteins.
The perception of colour is not entirely that exhibited under standard laboratory conditions, as in the assessment of anomalous colour vision, but in nature is influenced by illumination, contrast, fatigue and other factors.
www.du.edu /~jcalvert/optics/colvisn.htm   (1374 words)

  
 Medicdirect - Comprehensive UK Health Information
Colour vision normally remains the same throughout life, but changes can occur as a result of diseases affecting the eye or brain or by the prolonged use of some therapeutic drugs.
Their abnormal colour vision may be noticed by other people with normal colour vision eg, teachers, or by a health worker performing a colour vision screening test.
However, most significant colour vision defects later in life are usually easily identifiable as there are often other abnormal visual symptoms eg, reduced reading vision, loss of side vision or poor adaptation to the dark.
www.medicdirect.co.uk /clinics/default.ihtml?step=4&pid=1367   (642 words)

  
 Introduction to the Bases of Colour Vision
The tragic case of the Colorblind Painter as described by Sacks is an example of an acquired colour vision deficiency--one that is due to life events such as brain trauma, disease, or the effects of a toxic agent.
Because acquired colour vision deficiencies are due to life events, they can be due to any of a number of different causes that affect the optic media of the eye, retina, visual pathways, or areas of the brain that process colour information.
Transient achromatopsia, a temporary loss of colour vision, is caused by a short-lived vascular insufficiency, apparently to V1 blobs and the thin stripes of V2 in the occipital cortex.
www.psych.ucalgary.ca /pace/va-lab/Brian/acquired.htm   (2145 words)

  
 Webvision: Color Perception   (Site not responding. Last check: 2007-11-06)
Colour vision processing in the primate visual system is initiated by absorption of light by three different spectral classes of cones.
Consequently, colour vision is described as being trivariant or trichromatic, and initial psychophysical studies demonstrated that colours could be matched by the use of three different primaries.
Rushton WAH (1963) A cone pigment in protanope.
webvision.med.utah.edu /KallColor.html   (4618 words)

  
 An explanation of congenital colour vision anomalies   (Site not responding. Last check: 2007-11-06)
Colour vision test plates (such as the Ishihara series) exploit the fact that if the brightness and saturation are carefully chosen a deutan (M) will confuse a green-blue colour with a blue-purple, while a protan will confuse a similar green-blue with a red-purple.
Acquired colour vision defects - which effect up to 10% of the population - occur as a result of a disease process in the eye.
The designers of a colour vision protocol should understand what each of the possible tests does well and combine them in a way that will discriminate between those candidates who have the required standard of colour perception from those who do not.
www.cleareyeclinic.com /col_vis.html   (1456 words)

  
 Ultraviolet Vision [SoBS - UoB]
The vivid colours of many animals and plants are not only a source of inspiration to artists and poets, but are of great interest to evolutionary biologists.
It appears that UV vision is a general property of diurnal birds, having been found in over 35 species using a combination of microspectrophotometry, electrophysiology, and behavioural methods.
Remember, because 'colour' is the result of differences in output of receptor types, this means that bees do not simply see additional 'UV colours', they will perceive even human-visible spectra in different hues to those which humans experience.
www.bio.bris.ac.uk /research/vision/4d.htm   (1202 words)

  
 Colour Vision 1
Those with so-called "normal" colour vision are called trichromats, those who we usually call "colour-blind" are called dichromats, and the very rare people who have no colour vision at all are called monochromats.
The ability of people to make perfect matches to any coloured light by mixing a very restricted number of other lights (three, for a trichromat) is the most important feature of colour vision.
In addition, notice that some colour sensations seem to be mutually exclusive: whereas we can have a reddish blue or a greenish yellow, etc, we can't have a reddish green or a yellowish blue.
mainland.cctt.org /istf/Craven/document98_part1.htm   (1354 words)

  
 Introduction to the Bases of Colour Vision
He thought that colour was based on the interaction of stimulus brightness and ambient light level.
He also showed that the colours that compose white light could not be further subdivided, but they could be recombined to form white light.
His conclusion was that colour is not the product of the external objects we see, but is a property of the eye itself.
www.psych.ucalgary.ca /PACE/VA-Lab/Brian/history.htm   (887 words)

  
 The Evolution of Color Vision
An animal has color vision if it has the capability of discriminating lights (scattered light as well as light sources) on the basis of the lights' spectral content, even when those lights are of equal subjective brightness.
The color vision of primates is not strictly homologous to the color vision of fish, birds, turtles, etc. Much of the machinery used for primate color vision arose independently long after similar systems developed (without being lost) in other vertebrate lineages.
The last phase in the development of color vision is the arrangement of wiring in the brain that allows an animal to segregate and classify objects according to their "color" (i.e.
www.talkorigins.org /faqs/vision.html   (4843 words)

  
 The Ishihara colour vision test   (Site not responding. Last check: 2007-11-06)
There he worked as an instructor in the Military Medical School where he was asked to devise a test to screen military recruits for abnormalities of colour vision.
In 1958 the “Law of School Health” in Japan required that a colour blindness check be done as part of an overall health check on young school children.
The Ishihara test is a screening device to quickly sift through a large population and sort them into those who are normal colour observers and those who MAY have a colour vision anomaly.
www.cleareyeclinic.com /ishihara.html   (1805 words)

  
 Colour Vision
The fact is that the horse is able to perceive some colours in a limited way.
Therefor in order to have colour vision all you need is cones receptive to the different colours.
Therefore they are green colour blind, and your lush green paddock would look something like a drab shade of grey to them.
www.horseoz.com /Horse_Talk/COLOUR/colour.htm   (449 words)

  
 New Scientist Breaking News - Colour vision ended human pheromone use
The development of colour vision may have led to Old World primates, and hence their human descendants, to lose their ability to detect pheromones, suggests a new genetic study.
In order to see the world in full colour, two copies of a colour vision gene are needed - one red, one green.
But when male Old World monkeys gained a second colour vision gene, about 23 million years ago, it meant a new approach to mate selection was possible.
www.newscientist.com /article.ns?id=dn3835   (567 words)

  
 Colour Vision
Nicol demonstrated to them the colour exhibited by polarised light through unannealed glass and was so impressed by Maxwell's eagerness to learn that he gave him a pair of polarising prisms.
Maxwell's major paper in optics, On the Theory of Colour Vision, was presented to the Royal Society of London in 1860 and was awarded the Rumford Medal.
It showed that colour blindness was due to individuals being unable to recognise red light and conclusively proved his theory of three primary colours.
www-gap.dcs.st-and.ac.uk /~history/Projects/Johnson/Chapters/Ch4_2.html   (596 words)

  
 About Colour Vision Systems   (Site not responding. Last check: 2007-11-06)
About Us Colour Vision Systems was established in 1989 with the merger of two organisations: one specialising in mechanical fruit handling, the other in industrial-grade electronics.
In our continued drive for excellence, Colour Vision Systems is committed to research and development, and our significant achievements in this field have been recognised by the Australian government.
Colour Vision Systems has offices in Florida, California and Australia, with agencies worldwide.
www.cvs.com.au /aboutcvs.html   (107 words)

  
 Ophthalmology and Optometry Center: Eye Care by Luis J. Vidaurri, M.D. and Kathi Wegiel, O.D.
As a result of this red-green colour vision deficiencies show blue and yellow colours clearer than red and green colours.
With atypical total colour blindness, the sensitivity to red and green, as well as to yellow and blue is so low that only very clear colours may be perceived.
The majority of those with colour vision deficiencies will be unable to follow the line or will follow a line different to the normal one.
www.geocities.com /alfredo_71/vidaurri_5.html   (1156 words)

  
 Colour Vision Polymorphism   (Site not responding. Last check: 2007-11-06)
The generalization that colour vision is a more developed and acute capacity in primates than it is in other mammals came from a consideration of the natural history of mammals.
The past two decades have brought much progress in our understanding of the basic features of primate colour vision and there is now extensive experimental support for this supposition.
All the catarrhines (Old World primates) studied so far have the same colour vision which is based on three classes of cone-pigment (trichromacy).
www.stir.ac.uk /staff/psychology/hmb1/colourvision.htm   (497 words)

  
 Firelily Designs - Color Vision, Color Deficiency
Obviously there is more to vision than I have described, but most of it takes place behind the eyes.
Both diabetes and glaucoma destroy vision by reducing blood supply in the retina, even though the specific mechanisms are different.
If the concepts of gray (night) vision seem to be swept aside in this discussion, it is because the rod cells' primary sensitivity range is most effective in very low light levels.
www.firelily.com /opinions/color.html   (3913 words)

  
 Color Vision 1   (Site not responding. Last check: 2007-11-06)
The eye's peripheral vision system only supports low resolution imaging but offers an excellent ability to detect movement through a wide range of illumination levels.
The retina is a thin layer of nerve cells which consists of partially of light sensor cells.
The eye's high resolution color vision system has a much narrower angle of coverage.
www.photo.net /photo/edscott/vis00010.htm   (813 words)

  
 COLOUR VISION GROUP   (Site not responding. Last check: 2007-11-06)
The Colour Group of the Department of Experimental Ophthalmology studies the cortical processing of colour information in complex scenes and objects.
the interaction between colour and the other sub-modalities of vision (form, depth and motion) and how the "intrinsic images" of the world are combined to form a unified percept;
colour constancy and the effect of top-down influences on colour appearance;
www.uak.medizin.uni-tuebingen.de /forschung/colourvision.html   (61 words)

  
 Colorblind Homepage
It explains why you may be colorblind and what teachers, school nurses, and parents should know about being colorblind.
Two color vision tests for the military, aviation examiners, and employment agencies to test for all color vision deficiencies including tritan (blue/yellow).
I want to test my color vision on-line using the most popular color vision tests doctors and school nurses use to detect colorblindness.
colorvisiontesting.com   (173 words)

  
 Colour Physics FAQ
This FAQ concerns the measurement and control of coloured surfaces such as plastics, textiles, surface coatings etc. It is intended for practitioners rather than theoreticians.
Those requiring a more theoretical introduction to colour science or information about digital colour image reproduction might prefer to start by consulting the Poynton Colour FAQ.
If your question is not in the FAQ you may wish to consider version 3.0 of the FAQ which is available as a PDF file.
www.colourware.co.uk /cpfaq.htm   (231 words)

  
 Colour-vision software downloads   (Site not responding. Last check: 2007-11-06)
Video Vision is a POS system that has everything you need to control your video rent al business.
Costume Vision is a extremely powerful POS system that has everything you need to control your Tuxedo / Fancy Dress / Costume rent al business.
Acute Vision is a stylish news client designed to download pictures, video and music from binary news groups.
www.freedownloadsoft.com /colour-vision.html   (580 words)

  
 Colour Vision Systems, Inc.   (Site not responding. Last check: 2007-11-06)
Colour Vision Systems is recognized as the world leader in precision fruit sorting and blemish grading equipment.
Our systems utilize the latest technology in electronics and materials to produce the only vision machine that will eliminate human graders.
Documented research has proven the Colour Vision Systems Grading and Sorting abilities to be faster, more consistent, and more accurate than any other machine or human.
www.cvsusa.com   (103 words)

  
 [No title]
The issue is not identifying colours by name, though people with colour-vision deficiency are often able to do so, even for colours they cannot actually see, because they have learned what objects are what colours throughout their lives.
Colour vision is additive: Different wavelengths of light combine to form the millions of hues detectable by a person with normal colour vision.
When foreground and background colours are too close to the same hue, they may not provide sufficient contrast when viewed using monochrome displays or by people with different types of colour deficits.
www.joeclark.org /book/sashay/serialization/Chapter09.html   (9309 words)

  
 Colour Vision   (Site not responding. Last check: 2007-11-06)
Approximately 1 in 12 males and 1 in 200 females have defective colour vision.
This can affect the ability to perform some everday tasks and in some cases may be a bar to certain occupations.
There are many different types and severities of colour vision defect.
www.city.ac.uk /optometry/html/colour_vision.html   (217 words)

  
 Fact Sheet on Colour Vision Defects (colour blindness) - The IEE
Defective colour vision, commonly known as colour blindness, is a serious issue which affects the life and work of approximately 1 in 12 men and 1 in 200 women.
 Although actual colour-blindness (the perception of the world in shades of grey) is rare, individuals with defective colour vision to any extent may experience problems in certain careers.
This fact sheet published by the Engineering Policy Department, explains how defective colour vision arises and answers some of the common questions asked by those who suffer from it, as well as those asked by employers.  The document has been completely revised and updated.
www.iee.org /Policy/Areas/Health/cvdintro.cfm   (168 words)

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