How to find all the colors in a photo with Ruby

Does anyone know of a Ruby library that can list all of the colors in a photo, as well as listing them in order of frequency? Or is it possible that RMagick already can do something like this?

If no one knows of one, how exactly could I get started on making such a tool? I have a great idea for a program I'd love to try, however I just don't know much about image processing as I've never done it.

I'd be very grateful for any tips or info to point m开发者_Python百科e in the right direction! Thanks!

color_histogram