# How do I find the absolute color of someone's eyes in a photograph?

The color of my eyes is between green and blue. I've always been curious if it's more blue or more green. People's opinions are of course different, so I would like to find it out scientifically.

How can I analyze colors in picture with computer software and get statistics of colors in it? I would like to know how much blue it is and how much green it is.

And, I am not only interested in finding that about my eyes: I would like to know how to find the color of anybody's eyes. For example, how much brown it is. I don't think this is possible with an RGB scale. I think statistical output with all or defined colors and their percentages would be neat. Is there a way, or do I really need to rely solely on peoples opinion?

This is my left eye and this is my right eye.

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You're still going to have to rely on people's opinions to some degree, because people's opinions on where blue stops and green begins aren't just limited to eyes. More on this here: blog.xkcd.com/2010/05/03/color-survey-results – mattdm Nov 4 '12 at 15:53
Good point! However, I think there does have to exist scientific norm for color naming and relations between colors. – gadelat Nov 4 '12 at 16:44
Color distinction is not the same in all languages. Many do not distinguish between blue and green actually and they are just considered shades of each other. – Itai Nov 4 '12 at 17:10
Just found this is a very interesting read to see how confusing it can get! – Itai Nov 4 '12 at 19:36

Actually neither a correct calibration can ensure that you are going to see you absolute color. Your cornea acts (even if slightly) as a prismatic lens, which refract light with different angle depending on their frequency. Then the light would go though another lens (your eyes or a camera) therefore being refracted again (think about chromatic aberrations).

Theoretically if you put two people at a certain distance from you, one would say that your eyes are blue, and one green.

A method to achieve the better result possible would be then to photograph your eye in the same light, from very near, under calibration and from different angles. Then you could check the histograms of the image, and find out an average one. From that you could maybe think of some conclusions (notice that yellow colors are made using green - blue) therefore you could have a bigger green histogram then it is supposed to... If you are using a simple tool (there are softwares which display more colors).

There is also a psychological aspect to the whole story

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I've thought about how to do a science experiment, such as for a gradeschool project, to determine whether eye color changes in a person. Some of us are told that our eyes change to match clothing, or with mood, etc.

I was thinking to make a hole in a Kodak grey card, and hold it up to an eye, and photograph the eye withnthe gray around it. Adding some other reference swatches, such as cut from paint sample chips, would help too.

Shoot under different lighting, and try and shoot different days under the same light. In all cases, adjust the shot based on the gray card.

An absolute color would require careful calebreation of the camera, as well as adjustment for the light. Then the hue angle + color space, or the ab values of Lab, would be meaningful.

But... as the above experiment shows, calebration doesn't work since the eye color of some blue-eyed people changes substantually with the light source. For any color, shifting the light will loose some color information. So absolute color can only be determined with a standard controlled light, and that's not necessarily useful since it changes in a way that is not soley determined by the different light. You would need a spectrograph for a true answer, and measure different colored flecks in the iris at that!

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I don't think you're going to be successful using photographs. You'll have too many variables. The light temperature, intensity, and overall quality will affect how the iris appears. The camera sensor will be another one. Even under the same lighting conditions, different sensors may record different renditions. Next, the RAW processor (or automatic JPEG conversion) will also influence hue.

I think a non-photographic solution will be your best bet for repeatable and accurate eye color assessment.

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downvoted because you actually can get a colorchecker (standards of colors) and calibrate the white balance as well as color appearance. You may be not 100% sure, but still you're going to see images with a decent fidelity. Of course your screen has to be calibrated too. – Noldor130884 Jul 17 at 12:40

First, you have to calibrate the colors in the picture. You'll need a calibrated target such as http://www.bhphotovideo.com/c/product/651253-REG/X_Rite_MSCCPP_ColorChecker_Passport.html

Then you can adjust the colors in the photo to match the target's calibration.

Of course, the definition of color varies, and you get different values if you are using different color spaces. But this will get you started.

I have no idea how you handle that different people see the same color differently. Perhaps that is more in the area of psychology.

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