Colour Vision & Colour Blindness

Melf

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i know that people have red, yellow. blue?, (yes and octorine) receptors

why is it?. when ive watched friends tv, they have and watch progs (higher/stronger than i can cope with?). cos i have always ask, (the friends,) to tone the red down.

so, are people born with with the same amount/number of recptors?
if so.! can the person (just born and growing up) adjust to their petents/guardians, viewing colour habits?

cos i cant watch progs with a high "red content"

so any answers then?
 

Jerry_B

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AFAIK, everyone is susceptible to various levels of colour and contrast when looking at an image (which is osrt of how tests for colour blindess work). You many be susceptible to particular colours more than your friends are - or they may be less susceptible than you are ;)
 
A

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Actually, I also find that other peoples' TVs are sometimes a bit too red - and I have excellent colour vision (the rest of my vision is crap, so I've had lots of vision tests) . I think they've simply become used to it and don't notice that the colour balance is off. It's the same with anything - live with something (or someone) that's a little bit wrong for long enough and it looks perfectly normal to you.
This is a page that explains about colour vision.
You can test your colour vision onthis page.
 

JamesWhitehead

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When colour telly was still fairly new in the UK, my Grandmother had
an enormous, floor-standing Philips model. Whenever I was in the
house, I would adjust the controls to produce as realistic a picture
as possible. Yet every time I went back, the colour was turned back
up to its maximum position and the image was saturated and blotchy.

The old witch, who claimed not to understand the controls beyond the
on-off switch, must have reset them every time. I came to think that
she felt she must get as much lurid colour as possible for her licence fee.
But maybe she just saw things differently. :rolleyes:
 

OneWingedBird

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The human eye has cone cells which detect either red, green or blue, and rod cells, which detect any light, but with higher sensitivity.

This has got me thinking...

Why do people with red/green colour blindness (who lack one of the types of cones) see both colours as the same? Surely the colour for which they lack receptors should appear as grey?
 

liveinabin

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James Whitehead said:
When colour telly was still fairly new in the UK, my Grandmother had
an enormous, floor-standing Philips model. Whenever I was in the
house, I would adjust the controls to produce as realistic a picture
as possible. Yet every time I went back, the colour was turned back
up to its maximum position and the image was saturated and blotchy.

The old witch, who claimed not to understand the controls beyond the
on-off switch, must have reset them every time. I came to think that
she felt she must get as much lurid colour as possible for her licence fee.
But maybe she just saw things differently. :rolleyes:


When you have cattaracts this can affect your colour vision making all colours seem muted. But this would have hppen over a long period and most people don't notice.


On another note the hubby and I often argue over what is green and what is blue. I have taken both the Ishihara (mentioned above) and City colour tests and are fine on both!
 
A

Anonymous

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BlackRiverFalls said:
Why do people with red/green colour blindness (who lack one of the types of cones) see both colours as the same? Surely the colour for which they lack receptors should appear as grey?

Good question, BRF! I'm afraid I don't know. Could it be that they don't actually have a total absence of one type of cone and a normal population of the other, but instead there is maybe a merging of the two? I'm just guessing. Or maybe the fact that very few of the colours around us are pure red or pure green - most are a mixture of colours? Maybe they would see pure red as a grey colour. I dunno.

Another question about red/green colour blindness is, why is it hugely more prevalent in men than women? About 7.5% of men have it to some degree, but only 0.1% of women. I mean, why?:confused:

There is an interesting little thing in the Science Museum in London, where you look at a picture which contains a lot of vivid red colours (flowers, bedspread and stuff). You then look down a tube which floods your retina with red light for 45 seconds. Then, when you look at the same picture again, what was vivid red a minute ago becomes a dull brownish colour. Fairly obvious, but it shows how one can become desensitised in a very short time.

Big Bill Robinson
 

OneWingedBird

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Another question about red/green colour blindness is, why is it hugely more prevalent in men than women? About 7.5% of men have it to some degree, but only 0.1% of women. I mean, why?

It's because the genes for colour blindness are both recessive and on the 'wrong' part of the X chromosome.

As we have two pairs of chromosomes for everything, you need to have the recessive trait on both for it to be manifested, otherwise it is overruled by the dominant version on the other chromosome.

In men, the Y chromosome is (for arguments sake if not precisely) an X chromosome with about 1/4 of it missing, so for any genes that would be on the missing section there is only one copy, meaning that a recessive trait on the corresponding part of the X chromosome will always manifest, as there is no possibility of there being a dominant version to overrule it.

For a single gene this doubles the chance of the trait being present in males, I might imagine that where several recessive genes are required in combination to make something really cock up, the probabilities will multiply out eg 2^#ofgenesinvolved.

I can't help thinking that I've just made that sound a lot more complicated than it really is...
 

Imperial_Call

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I've "always" had an aversion to the colour red, it drives my eyes mad, on ocassion I've had to hold green paper in front of my eyes to counter the effect of looking at something red ...
 

OneWingedBird

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I remember seeing a documentary on this guy once, quite an established artist, possibly european, who suffered a head trauma which left him with no colour vision... have a vague memory of him producing some quite frightening art after that, all in this freaky grey scale...

Does this ring a bell with anyone though? I'm scuppered if i can remember who it was...
 

WhistlingJack

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I doubt it's who you're thinking of, but Monet's ability to see colour was certainly impaired: -

Although Monet was diagnosed with nuclear cataracts in both eyes by a Parisian ophthalmologist in 1912, at the age of 72, his visual problems began much earlier. Soon after 1905 (age 65) he began to experience changes in his perception of color. He no longer perceived colors with the same intensity. Indeed his paintings showed a change in the whites and greens and blues, with a shift towards "muddier" yellow and purple tones. After 1915, his paintings became much more abstract, with an even more pronounced color shift from blue-green to red-yellow. He complained of perceiving reds as muddy, dull pinks, and other objects as yellow. These changes are consistent with the visual effects of cataracts. Nuclear cataracts absorb light, desaturate colors, and make the world appear more yellow.

Monet was both troubled and intrigued by the effects of his declining vision, as he reacted to the the foggy, impressionistic personal world that he was famous for painting. In a letter to his friend G. or J. Bernheim-Jeune he wrote, “To think I was getting on so well, more absorbed than I’ve ever been and expecting to achieve something, but I was forced to change my tune and give up a lot of promising beginnings and abandon the rest; and on top of that, my poor eyesight makes me see everything in a complete fog. It’s very beautiful all the same and it’s this which I’d love to have been able to convey. All in all, I am very unhappy.” – August 11, 1922, Giverny.

Art, Vision, & the Disordered Eye
 

eburacum

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RE: What would a new colour look like?

Claude Monet had a cataract removed, which supposedly allowed him to see wavelengths further into the UV spectrum than most people.
He saw this additional shade as blue, so the answer (at least as far as he is concerned) is 'blue'.
http://standinglooking.blogspot.com/200 ... iolet.html
 
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eburacum

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In the other direction, just outside the range of human vision is the so-called 'red edge', a wavelength where vegetation suddenly becomes very reflective. This reflectance is used in satellite photography to detect various kinds of vegetation and agriculture; it might also be useful in detecting plant-life on extrasolar planets.

To get an idea of what the world would look like if we could see the 'red edge' wavelengths, take a look at this IR image;...
http://www.flickr.com/photos/zachstern/ ... 2/sizes/l/
 

James_H

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Is this why photos of vegetation taking with IR film always look a little weird?
 
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