Red-Green Color Blindness doesn’t mean You can’t Distinguish Red from Green
- Posted by Daniel Flück on September 14th, 2007 filed in Thoughts
Often people think that if you are suffering from red-green color blindness you can not distinguish red from green at all. But they are wrong.
The term red-green color blindness isn’t accurate and doesn’t describe the actual color vision deficiency correctly. If you have a look at the confusion lines of the CIE 1931 color space you will see, that there are many different lines in the color space which connect undistinguishable colors to a colorblind person. Therefore a red-green color vision deficiency makes you colorblind to many more colors than just red and green.
On the other side it depends strongly on the brightness and saturation of colors to make them hard to distinguish if you are colorblind. Colorblind people often develop some sort of color intuition which is based not only on the hue but also on the brightness of the color they see. Something which is hard to imagine if you have normal color vision.
For example some shades of red are close to green, others close to brown and again others are even close to black. The following list shows a few examples of colors which look close to each other and can’t be distinguished easily if you are suffering from red-green color blindness:
- yellow — bright-green
- orange — grass-green
- apple-red — leave-green
- dark-green — brown
- blue-green — gray — purple
- dark blue — violet
As a conclusion you can say that some reds and some greens are very well distinguishable. It depends very much on the brightness and the saturation of each color to make them undistinguishable for a red-green colorblind person.
October 24th, 2007 at 15:42
a patient with deuteranopia lacks which color pigment??? i thought it was red and green, am i right?? thank you folr helping marjolijn clarke
October 24th, 2007 at 19:35
Marjolijn, deuteranopia is also called green-blindness and you would lack the green color receptors in your eyes. It is one of the subtypes of red-green color blindness.
November 27th, 2007 at 15:23
I can see red and green, but I cannot
focus on either one if they are together.
Put a green dot in a red background and
my eyes chase the dot around. It looks like the dot is moving. I guess some sort
of optical illusion. Is this normal?
December 6th, 2007 at 19:55
George Hoffmann, You may have a refractive error (glass correction). If you see objects with red in the background better than green, you may be a bit myopic (nearsighted) If images look clearer with a green background you may be a bit hyperopic ( farsighted).
March 27th, 2008 at 0:47
I can’t see red but i can see green what is that called??
March 27th, 2008 at 10:38
Anthea, what does it mean “you can’t see red”? I always mix red with brown or green and can’t see certain red flowers if I’m not close enough. I suppose it is just some sort of red-green color blindness but which isn’t that easy to determine.
March 30th, 2008 at 4:32
When I look at something on the board in school and its in red it’s like its not there at all. But i can see it when i get closer.
March 30th, 2008 at 20:02
Anthea, it sounds like you’re suffering from Protanopia (Red-Blindness). This causes to see reds darker then everybody else. Check out the D-15 test to find out more about it.
April 8th, 2008 at 7:16
I have kind of an odd situation. When I was taking online red-green colorblind tests it was very hard for me to see the expected item and hurt my eyes and took me some time to come up with an answer. I did about 50/50 on correctness. The thing is I am not sure what problem is. I have a very hard time seeing different shades of red and green. Like greens and blues can appear the same color to me, as well as orange and red. I have had this problem since I was really little. Any Ideas? Sorry it’s so long.
April 8th, 2008 at 22:21
Jennifer, just try out the following Color Arrangement Test. Comparing your answers to some of the others in the article or comment section will tell you more about your color blindness.
April 15th, 2008 at 21:42
My husband is a truck driver and when he went for his physical they used the out-dated color blindness book, he distinguished about 50/ 50 of the numbers. The doctor approved him for 2 yrs on the dot, but put a stipulation in for him to see an opthomologist due to a red-green distinction prob. When he interviewed for his job, they sent him to another doctor, and they checked to see if he could distinguish colors such as on a color chart. He passed they mentioned they don’t use the books anymore? Which is right, for the dot physicals are they suppose to use the books or not???
April 16th, 2008 at 21:52
Melissa, this really depends on the state, country, authority, … I personally believe, that the “dot” (Ishihara) test is to strong for many cases. If you can get passed a lantern test (three different colors displayed by a lantern) you should be able to complete most task on earth. But some people think, that you have to pass stronger tests to be a “secure” human being.