This painting by Gerhard Richter is called 256 colors. The painter is fully committed to this kind of work, as you can see here. When visiting the San Francisco Museum of Modern Art (SFMOMA) (I’m getting literate…), the guide asked the following question:
Do you think the colors are positioned randomly or not?
Not a trivial question, is it? And you, would you say it is random? This work dates back to 1974, when computer screens mainly displayed green letters on a black background. So it seems the artist did not benefit of computer assistance.
There are many ways to interpret this plain English statement into statistic terms. For example, are the colors, with no ordering, uniformly distributed? (OK, this doesn’t mean at all (true) randomness, but this is a question…) It would be nice to have the 256 colors in RGB. In this color model, (0,0,0) is black, and (255,255,255) is white. I think that there are rather more dark colors than light ones, ie more data points near the (0,0,0) vertex than near the opposite one, in the RGB cube. So a test of uniformity would probably be rejected.
A more subtle way to interpret uniformity in the painting would be to take into account the position of the colors… Any idea how to check that? I have no clue.
Here is a larger one, 1024 colors…
Statisfaction 
To test for the impact of the position: spatial autocorrelation test ?
That would do perfectly indeed. A question to Pierre (and others): do you think Python is adapted for programming a request to get RGB colors?
You mean you put the JPEG picture as an input and it gives you the color matrix? I guess it’s doable in python, there might be libraries, but I don’t know for sure. It’s possible that R has packages for that kind of stuff too, by the way. Did you search already?