Is there such a thing as complete color blindness?
357436
my uncle is completely colorblind. all he can see is black brown and white. he cant see very well because the colors blend together.
316761
There are different kinds of color blindness.  The most common is red/green.  This occurs when the chromosome that codes for how we see color is missing either the red or green gene or else there is a chimeric gene (it has both red and green on the same gene) that only allows one of the colors to be expressed. If the chromosome doesn't have both the red and green gene being properly expressed than the person will be red/green color blind.  This means that he/she will not be able to perceive red (if that is the gene missing) or green (if that is the missing gene) There are no drugs that can help this, because you are missing the gene -- there is no way to "fix" that.  Hope that helps.  :)
276633
No. \nHumans see the color purple as stimulation of red AND blue receptor (Purple is not a primary color). \nAnyway, whatever colorblindness you have, it never would affect only one color, because the ratio of the excitation of two or more different types of photoreceptors contributes to most colors (You have only three different kinds of color receptors, but you can see millions of colors). \nSo deficiency in one photoreceptor type affects not only its primary color but many others too. \n\nA nice webpage for a simulation of how color blind people see colors are \nhttp://www.vischeck.com/\nhttp://jfly.iam.u-tokyo.ac.jp/html/color_blind/text.html#see
245658
Yes, from a physics perspective there are an infinite number of colors.\n\nBut from the perspective of your retina, there are a finite number that you can perceive, in the thousands as I recall.
863959
see: http://en.wikipedia.org/wiki/Color_vision\nhttp://en.wikipedia.org/wiki/Color_blindness
174769
color-blindness is a sex-linked (aka x-linked) trait \nfor a female it is X^c X^c\nfor a male it is X^c Y\n\nwhere C is normal vision and\nc is color-blind
806627
This is partially true, partially false.\n\nWith regards to purple, most people would agree that purple light is always some mixture of reddish and bluish light.   I.e. you can imagine two knobs, one raising and lowering the red and the other raising and lowering the blue, and you can get many shades of purple.  There may be other hues added in as well, but there is *always* red and blue (if not, we rarely call it purple).\n\nIn other words, if we didn't have the word "purple" in our language, we would probably call it something like "reddish blue" or "bluish red".\n\nBut we cannot do the same with red and green.   We have a very hard time imagining, or pointing to, a color that is "reddish green".  If given only a red and a green knob, the result will be make the color more or less neutral (gray or white).\n\nLikewise with blue and yellow.  (Some people will respond that green is bluish yellow, but that's because many people are used to mixing pigments on paper ... we're talking about mixing lights.)\n\nThese two pairs,  red-green and blue-yellow, are *fundamental* pairs.  We call them "oppositional".  (There is also a third opponent pair ... light-dark ... but as we're just talking about color here, we can ignore that one for the moment.)  This is called the "opponent theory" of color vision and is associated with Ewald Hering.\n\nSo in that sense we can call these four colors "fundamental" hues"  because all color we see can be mixed using knobs of these four colors.\n\nPeople will also wonder about the red-green-blue primaries, and the fact that we know we have red, green, blue photoreceptors in our eyes.  These would also seem to be fundamental hues (as evidenced by the computer monitor on which you are reading these words ... that monitor is able to simulate a wide range of colors using just red, green, and blue).\n\nThese two theories ... the "opponent theory" and the "trichromatic theory" competed for a long time until we found a way to reconcile them.  Basically, we have three types of photoreceptors, but they are wired in a way in our retina, that by the time signals are travelling down our optic nerve, the red-green are antagonistic signals as are yellow-blue.
26622
D. color blindness\n     That's kind of a trick question. When I looked at it, I thought "this can't be color blindness, because that's a failure to see much of a difference between mainly red and green." But in reality, that is what it is. You not only fail to see red but also green. So the answer is indeed D.
237598
Color blindness is dependent on the visual spectra.  OK..thats lots of jargon so here is simple way to look at it.  You visual light is while however if you put a prism you will see rainbow colors (remeber prism experiemnt?).  Well, your eye is designed to synthesize white visual light into optical shades (rainbow) and hence one can see colors.\n\nNow two ends of this color spectra are Blue and Red and everything in between.Depending upon, where there is a deficiency in your prism (eye), it can vary in color interpreation.  Hence, it varies with ansers below. There have been examples in the history that baristors (lawyers in English court) went to court with Red coat (instead black) and judges thought that person was a prankster...this is before color blindness was identified..
815779
You have color issues. Get some help!
143118
Yes.  Black is the condition of no visible light reaching the eyes.  However, because 'colour' is an arbitrary way that humans identify the sensation of electromagnetic waves, the fact that 'black' can be sensed makes it a colour.  However, black can either be the absence of all light or the combination of many other colours.
618977
Yes. My grandmother is blind from a disease known as maculuar degeneration.  She dreams in full color.  She doesn't know if the colors look like what everyone else sees, according to her.  But she dreams about an apple and it is what she thinks red should be.  She can "see" what an apple looks like by feeling its shape and texture.  She imagines the rest.
84161
I am colorblind and my opinion is that it does affect your lifestyle. especially when as a kid, in kindergarten and elementary school, where everything is color coded, or the teacher uses a tone of green in the blackboard. Many times teachers do not understand a student that has color deficiency. They label him as stupid or slow!!! A deficiency like that should be accepted, and there are many ways to help students with this problem and not making them feel guilty or worse offended. Of course it looks weird when a kid draws a picture of a green person or when he can't distinguish between the brown or red, or blue and purple. People like me do not understand words that other people name colors like. Some colors we can see of course, it's not like black and white; however, there are others that they are just the same color with a diferent name. IT DOES AFFECT A PERSON'S LIFESTYLE. Try matching your clothes, that gets a little bit harder being colorblind.
965726
The color photoreceptors are cones, and they are part of day vision (or high light vision) only.  If you're seeing strange dots of color in low light, it could be an issue with your cones receiving false input or something like that, because normally they are not excited at all in low light.  You should probably visit an opthamalogist.  Incidentally, the cones are not sensitive to red, blue, and green, but blue-violet, blue-green, and yellow-green.
1151256
Color blindness, or color vision deficiency, in humans is the inability to perceive differences between some or all colors that other people can distinguish. It is most often of genetic nature, but may also occur because of eye, nerve, or brain damage, or due to exposure to certain chemicals. The English chemist John Dalton in 1794 published the first scientific paper on the subject, "Extraordinary facts relating to the vision of colours", after the realization of his own color blindness; because of Dalton's work, the condition is sometimes called Daltonism, although this term is now used for a type of color blindness called deuteranopia (see below).\n\nColor blindness is usually classed as a disability; however, in select situations color blind people have advantages over people with normal color vision. Color blind hunters are better at picking out prey against a confusing background, and the military have found that color blind soldiers can sometimes see through camouflage that fools everyone else. Monochromats may have a minor advantage in dark vision, but only in the first five minutes of dark adaptation.
131547
colours only mean you perceive things differently. if you were colour blind it may make things harder for you if you had to determine colours. otherwise, it probably has very little significance.
1174760
Improved sight in the dark? :)\nActually I'm not really kidding since men mostly have some 'color-blindness'. So you may have something there. After all the men needed a better night vision since they were the hunters/providers.(ref 1)\n\nActually what do you mean by color-blindness (check reference 2)?