Dribble has a great feature that lets you browse shots by similar colors:  

[![Note the color droplets on the right side of the image](https://i.stack.imgur.com/5snUK.png)](https://i.stack.imgur.com/5snUK.png)

What is the easiest way to generate something like this in Ruby? Are there libraries or services that can manage this kind of processing? I currently have 26k images which I'll need to process and I'm evaluating the best way to do so.