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Topic: Color vision


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In the News (Thu 18 Apr 19)

  
  Evaluation of a New Color Vision Test
A battery of color vision tests including the Ishihara, Panel D-15, and the anomaloscope were used for the diagnosis and classification of color deficiency.
The frequency of individuals identified as color deficient (7.5% of the males and 0.6% of the females) was similar to that expected in the general population.
The results showed that the test was useful in screening this population for color vision deficiencies, and that the prevalence of color vision deficiencies was similar to the prevalence found in the general population.
colorvisiontesting.com /color6.htm   (1394 words)

  
  What is Color?
The opposition of these colors forms the basis of color vision.
For example, contrasting colors are diametrically opposite on the color circle.
The artistic term “hue” is the edges of the square (the outside of Hering’s circle); “saturation” represents where the color is placed between grey middle and the colored edge; “value,” also called “brightness” or “luminance,” is the intensity of the color and is the third attribute.
webexhibits.org /colorart/color.html   (301 words)

  
 The Evolution of Color Vision
As this is grist for the evolution of color vision mill, we're literally ripe for the addition of a fourth cone class.
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.
Color vision is mediated by cones, so named because of the shape of the receptive part of the cells.
www.talkorigins.org /faqs/vision.html   (4843 words)

  
 Webvision: Color Vision. by Peter Gouras
Color and all vision are in a sense illusory depending only on messages that pass between millions of neurons that reside within the darkness of our skull.
The Opponent Color Theory of the 19th century physiologist Ewald Hering (Hering, 1964; Hurvich, 1981) derived by the analysis of subjective human color vision is in general correct, although the idea of opponent colors was described earlier by Goethe and Schoepenhauer.
Knowledge of the physiology of color vision beyond striate cortex is sketchy because of the difficulty in exciting cortical cells in anesthetized monkeys.
webvision.med.utah.edu /Color.html   (8851 words)

  
 Color Vision Deficiency - healthinfochannel
Color vision deficiency results from a malfunction or absence of cone cells in the retina.
In normal color perception, all three populations of cones are present (trichromacy) and function normally.
People who perceive colors normally are known as trichromats, because they are using three populations of cones, one sensitive to red, one to blue, and one to green, to match any color in the environment.
www.healthinfochannel.com /colorvision   (584 words)

  
 AllRefer Health - Color Vision Test (Eye Test - Color, Ishihara Color Vision Test, Vision Test - Color) - Test/Medical ...
A color vision test checks your ability to distinguish between different colors.
In some circumstances, color vision testing is used to evaluate the function of the optic nerve.
The optic nerve is the main nerve connecting the eye to the brain.
health.allrefer.com /health/color-vision-test-info.html   (431 words)

  
 How color vision works
This simple hypothesis, however, is in conflict with the fact that the color that we perceive of an object is influenced by the color of the background, a phenomenon that is called simultaneous color contrast.
Defective color vision is a surprisingly common disase: about 8 % of all males and 0.5 % of all females are affected.
This type of color vision deficiency is inherited and is caused by mutations in the genes encoding the visual pigments of red sensitive L-cones (L-pigment) or green sensitive M-cones (M-pigment).
www.fz-juelich.de /ibi/ibi-1/Color_vision   (2186 words)

  
 Color Vision 1 - photo.net
Some people have a visual anomaly referred to as color blindness and have trouble distinguishing between certain colors.
Red-green color blindness could occur if the Rho and Gamma sensor curves exactly overlapped or if there were an insufficient number of either rho or gamma sensors.
Since rods all seem to share the same spectral selectivity characteristics, they cannot create a color image so one color of moonlight is probably as good as the next.
www.photo.net /photo/edscott/vis00010.htm   (813 words)

  
 Firelily Designs - Color Vision, Color Deficiency
The subject of color usage on the web comes up once in a while, so I thought it might be useful to pull together some basic issues for people who might be interested in color.
Color is another perceptual value; there is nothing about light at a wavelength of 700 nanometers that makes it red.
Color on color may seem (relatively) safe if you understand color deficiency, but there is one more catch.
www.firelily.com /opinions/color.html   (3912 words)

  
 Color & Vision
The color content of the light source is usually described in terms of the temperature of an incandescent emitter which produces a color spectrum closest in color to that source.
The color we perceive an object to be is determined by which wavelengths of light are absorbed or reflected by the object.
To make the eye "see" any color of the spectrum it is only necessary to stimulate the three types of cones in a manner similar to the way the actual color would.
www.luminous-landscape.com /tutorials/color_and_vision.shtml   (1397 words)

  
 Webvision: Color Vision. by Peter Gouras
Color and all vision are in a sense illusory depending only on messages that pass between millions of neurons that reside within the darkness of our skull.
The Opponent Color Theory of the 19th century physiologist Ewald Hering (Hering, 1964; Hurvich, 1981) derived by the analysis of subjective human color vision is in general correct, although the idea of opponent colors was described earlier by Goethe and Schoepenhauer.
Knowledge of the physiology of color vision beyond striate cortex is sketchy because of the difficulty in exciting cortical cells in anesthetized monkeys.
www.webvision.med.utah.edu /Color.html   (8851 words)

  
 Color vision - Psychology Wiki   (Site not responding. Last check: )
Color vision is the capacity of an organism or machine to distinguish objects based on the wavelengths (or frequencies) of the light they reflect or emit.
Color perception mechanisms are highly dependent on evolutionary factors, of which the most prominent is thought to be satisfactory recognition of food sources.
Incidentally, the CIE chromaticity diagram is horseshoe-shaped, with its curved edge corresponding to all spectral colors, and the remaining straight edge corresponding to the "purples" -- various mixtures of the red and violet that appear at the extremes of the spectrum.
psychology.wikia.com /wiki/Color_vision   (2565 words)

  
 Color vision - Wikipedia, the free encyclopedia
Color vision is the capacity of an organism or machine to distinguish objects based on the wavelengths (or frequencies) of the light they reflect or emit.
The advantage of color, which is a quality constructed by the visual brain and not a property of objects as such, is the better discrimination of surfaces allowed by this aspect of visual processing.
Color perception mechanisms are highly dependent on evolutionary factors, of which the most prominent is thought to be satisfactory recognition of food sources.
en.wikipedia.org /wiki/Color_vision   (1439 words)

  
 Color Vision Confusion
Color blindness is mostly inherited, or it may be acquired as a result of some illness, such as head trauma, or treatment.
The International Colour Vision Society is an international group of physiologists, psychologists, physicists, geneticists, optometrists, ophthalmologists and others who have a research interest in the many aspects of color vision and color vision deficiencies [22].
Color vision confusion or color blindness as it is usually known is a common impairment, affecting approximately eight percent of males and two percent of females.
www.otal.umd.edu /uupractice/color   (2379 words)

  
 Color Vision of Birds
The fundamental principle that is involved in color matches is that two physically different lights (i.e., 600 nm monochromatic light [orange] and an appropriate mixture of 640 and 580 nm lights [red and yellow] in the example of figure 5.4) are able to excite the population of retinal cones in an identical manner.
Birds may have a generalized system of color vision, but individual species may also have features of their eyes adapted to specific visual tasks or conditions, and attention to this ecological dimension in formulating hypotheses about visual function is likely to be critical.
The tetra- or pentachromatic color space of birds appears to be the most complex in nature and is likely involved in virtually all areas of the animals' lives, from the discrimination and recognition of objects to more complex behavioral tasks such as navigation, the classification of objects, and social and sexual behavior.
users.mikrotec.com /~pthrush/lighting/cvb.html   (6335 words)

  
 Color vision deficiency - Genetics Home Reference
Color vision deficiencies are a group of conditions that affect the perception of color.
Mutations in the CNGA3, CNGB3, GNAT2, OPN1LW, OPN1MW, and OPN1SW genes cause color vision deficiency.
Blue-yellow color vision defects are inherited in an autosomal dominant pattern, which means one copy of the altered OPN1SW gene in each cell is sufficient to cause the condition.
ghr.nlm.nih.gov /condition=colorvisiondeficiency   (1390 words)

  
 The Equine Color Vision Debate
Yet the anatomy of the equine eye suggests that some color perception is possible, and in the last 25 years, a few behavioral studies have attempted to test color recognition in horses.
Using color as the distinguishing characteristic to mark the rewarded choice, some studies determined that shades of red are visible to horses, while others found that blue, not red, is a recognizable color.
Color vision is not required for either successful foraging or reproduction, so it's not an essential survival tool for horses as it is for some other species.
equisearch.com /horses_care/health/anatomy/colorvision_012706   (1571 words)

  
 Color Vision Screen   (Site not responding. Last check: )
Red-green deficiency usually means difficulty identifying or distinguishing colors of which red or green is a component: telling blue from purple, dark green from dark brown or light pastel blue from light pastel pink.
A color deficient person may not be able to identify the specific color, but the effect is the same.
Color filter and tinted contact lens alter color appreciation, but they do not improve color perception; color filters reduce perception of some colors.
icare4u.com /color.htm   (526 words)

  
 Color Vision
Success with these plates defines the subject as having ‘normal color vision’ and completes the test for that person.
Subsequent plates appear increasingly bold in color to test for an increasing color deficiency.
Scoring: For subjects with other than normal color vision, diagnosis of type and extent of defect plates 11-24 are used.
www.nova.edu /hpd/otm/cop/ColorVision.htm   (861 words)

  
 Neuroscience for Kids - Color Vision
Color vision is not only a pleasurable experience, it also helps us locate and identify objects in the visual scene that would be hard to pick out in shades of gray.
That is, the color is encoded in the pattern of activity of a number of cells rather than in the isolated activity of one cell.
In a further apparent exception to the color constancy rule, a set of objects reflecting identical wavelengths from their surfaces (for example, red light-they should all look red) can appear to be completely different colors if set against different backgrounds, or when using different ambient lighting conditions.
faculty.washington.edu /chudler/eyecol.html   (3733 words)

  
 handprint : light and the eye
The premise that millions of distinct colors can arise from the stimulation of three different color receptors is called the three color or trichromatic theory of color vision, first proposed in the 18th century.
This is the most general chromatic contrast in color perception, and it appears to have a strong influence on the development and use of color terms in almost all languages.
Color for Science, Art and Technology edited by Kurt Nassau (North Holland: 1997) is a miscellany of rather unusual chapters on color, such as "The Fifteen Causes of Color", "Color in Abstract Painting", "Organic and Inorganic Pigments", and "The Biological and Therapeutic Effects of Light".
www.handprint.com /HP/WCL/color1.html   (16422 words)

  
 Color Matters - Vision - Color Vision for Mice
Normal mice failed to discriminate yellow versus red lights; the genetically altered mice demonstrated their new color vision by choosing the correct panel in 80 percent of the trials.
The new research is the most definitive yet in shedding light on the first steps that led to the emergence of color vision found today in most primates, including humans.
Humans with the most common form of color-blindness and mammals with poor color vision are unable to differentiate between reds and greens.
www.colormatters.com /vision_mice.html   (522 words)

  
 Prevent Blindness America - Color Blindness
Color vision deficiency is a term used to describe a number of different problems people have with color vision.
People with a family history of color vision problems and those who are having problems seeing colors should be tested.
If you have color vision deficiency, it is possible for you to learn to recognize color by other means.
www.preventblindness.org /eye_problems/colorvision.html   (301 words)

  
 Color blindness - color vision
Color blindness may be a hereditary condition or caused by disease of the optic nerve or retina.
These color problems are linked to the X chromosome and are almost always passed from a mother to her son.
Color vision deficiency is most commonly detected with special colored charts called the Ishihara Test Plates.
www.stlukeseye.com /Conditions/ColorBlindness.asp   (469 words)

  
 color and color vision   (Site not responding. Last check: )
Opsin genes, cone photopigments, color vision and color blindness,
Color Vision Molecular Genetics, Neitz Color Vision Laboratory
Color and Vision Questions and Answers posed by the Munsell Color Science Laboratory, Rochester Institute of Technology
www.yorku.ca /eye/color.htm   (100 words)

  
 handprint : color vision
Vision and color are at the heart of painting.
Here is the most comprehensive discussion for artists of color perception, color psychology, "color theory" and color mixing available online, and one of the most comprehensive available anywhere in any format.
 constraints on color vision (monochromatic, dichromatic & trichromatic vision)
www.handprint.com /HP/WCL/wcolor.html   (57 words)

  
 Color Vision 1 - photo.net
Our perception of which color we are seeing is determined by which combination of sensors are excited and by how much.
Red-green color blindness could occur if the Rho and Gamma sensor curves exactly overlapped or if there were an insufficient number of either rho or gamma sensors.
Since rods all seem to share the same spectral selectivity characteristics, they cannot create a color image so one color of moonlight is probably as good as the next.
photo.net /learn/optics/edscott/vis00010   (839 words)

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