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I often heard about red/green deficiency, this is not too rare for men. But I never heard about a corresponding yellow/blue deficiency. Any idea why ?
Regards
Thomas
www.thomas-weller.de
Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning.
Programmer - an organism that turns coffee into software.
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From the Wikipedia:
Blue-yellow color blindness
Those with tritanopia and tritanomaly have difficulty with discriminating blue and yellow hues.
Color blindness involving the inactivation of the short-wavelength sensitive cone system (whose absorption spectrum peaks in the bluish-violet) is called tritanopia or, loosely, blue-yellow color blindness. The tritanopes neutral point occurs near a yellowish 570 nm; green is perceived at shorter wavelengths and red at longer wavelengths. Mutation of the short-wavelength sensitive cones is called tritanomaly. Tritanopia is equally distributed among males and females. Jeremy H. Nathans (with the Howard Hughes Medical Institute) proved that the gene coding for the blue receptor lies on chromosome 7, which is shared equally by men and women. Therefore it is not sex-linked. This gene does not have any neighbor whose DNA sequence is similar. Blue color blindness is caused by a simple mutation in this gene. (2006, Howard Hughes Medical Institute).
Or, go for the whole story: http://en.wikipedia.org/wiki/Color_blind#Blue-yellow_color_blindness[^]
Some time ago I was looking for a summer job - and tried out in a pigment plant. They give you an amazingly extensive color vision test: matching tiles. Here's the setup:
A stack of 64 mixed tiles, 16 each of r,g,b & y in dull muddy shades
A matching sheet containing 4 rows each of 16 r, g, b, or y tiles that are NOT ordered by shade.
You are to match them to one another.
But
There is not one of each.
So, no guesses, now relative comparisions: they either look different or you can't tell.
My Y/B was found to be exceptional (putting an end to some arguments I had in lab).
My R/G was ca. normal (slightly below, but within 1 or 2 tiles, which is a normal deviation).
To this day, I argue with people about blues, dark blues in particular, as compared to black. I also have to (try to) explain to people that the color temperature of the light illuminating a subject makes a huge difference.
"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"How do you find out if you're unwanted if everyone you try to ask tells you to stop bothering them and just go away?" - Balboos HaGadol
"It's a sad state of affairs, indeed, when you start reading my tag lines for some sort of enlightenment?" - Balboos HaGadol
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Alexandre GRANVAUD wrote: what if i see all colours but some switched ?
How would you know?? :P
Sad but true: 4/3 of Americans have difficulty with simple fractions.
There are 10 types of people in this world: those who understand binary and those who don't.
{o,o}.oO( Check out my blog! )
|)””’) http://pihole.org/
-”-”-
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Same here, trouble with red+green. But it's not color blind, so I didn't vote. Voting color blind probably skews these wonderful statistics.
So, if you feel that more computer geeks are more color blind than average, vote "blind".
Otherwise vote "no". 
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Actually, that is what is called 'color blind'. The inability to distinguish different colors is color blindness. It is not ALL colors; normally just red and green.
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That's definitely color blindness.
It's strange, though, that it hasn't gotten a politically correct acronym yet... Like CVD for color vision deficiency.
I have trouble with red+green, but actually it's only the red color component that is the problem. I perceive red color less vividly than other colors, so I for example have trouble viewing red text on a black background, while I clearly see green text on a black background.
peterchen wrote: So, if you feel that more computer geeks are more color blind than average, vote "blind".
No, that is not correct. The question was if you were color blind, not if you think that others are color blind... Freely interpreting the question as what you think that it should be really would skew the statistics...
Despite everything, the person most likely to be fooling you next is yourself.
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Where I grew up there was a clear distinction between a deficiency and total blindness, this is also distinguished by the standard tests. (And definitely not for political correctness - that had a completely different meaning  )
Guffa wrote: No, that is not correct.
I was more expressing how I value such a black&white question. 
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I am quite color-blind, about as bad as you can be without seeing just pure black and white. Without contextual clues (like the order of the stoplight, jeans are usually blue, etc.) I have a really hard time distinguishing these color combination:
Red-green (really common in men)
Blue-pink-purple
Yellow-green (a real problem with LEDs in electronics that I work on)
Brown-red
And any kind if "subtle" (mauve, salmon, taupe, etc.) or non-primary color is kind of lost to me.
This is caused by missing "cones" in my eyes, an inherited condition.
"Color blindness (color vision deficiency) is a condition in which certain colors cannot be distinguished, and is most commonly due to an inherited condition. Red/Green color blindness is by far the most common form, about 99%, and causes problems in distinguishing reds and greens."
I recommend taking one of these tests:
http://www.sometests.com/tests/SelfAssessment/TheColorBlindnessTest.html[^]
But, my point is, as software engineers, it's really important NOT to put such a huge percent of users needlessly in a difficult position. For example, never use color as the primary indicator of state; combine color with an icon or text. Use "color blind safe" pallets. There are examples of these on the Internet. If you go out of your way to have a color-blind-friendly product, chances are it will also be better for normal users.
PS. I've never had a problem seeing a traffic light, although I did once try on a pair of purple jeans in a store!
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Let it be know to all who perceive this communique:
The wearing of plaid pants by adult males is a crime against nature.
Thus was it written,
Thus was it read.
For those committing aforesaid atrocity,
Your "friends" are laughing at you,
the pretty young maidens shake their heads in pity,
and your particular idea of diety is crying
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Balboos wrote: Thus was it written,
Thus was it read.
Thus was it written,
Thus was it red.
Software Zen: delete this;
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First time I came to the Code Project I thought the designer of the site was colour blind...
Oddly enough I've grown to love the orange and green and regularly try and get orange into my websites. A method to Chris' madness.
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What orange and green? You must be color blind, it's purple and yellow
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Ah crap. I spoiled the ballot then. Better call for a re-vote.
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Yah it's cool I like it. Definitely stands out from the crowd. 
Sad but true: 4/3 of Americans have difficulty with simple fractions.
There are 10 types of people in this world: those who understand binary and those who don't.
{o,o}.oO( Check out my blog! )
|)””’) http://pihole.org/
-”-”-
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