Essentially:
* Bing image search for the phrase entered
* Downloads first result from Bing and saves to disk
* Your browser then loads the downloaded image
* http://jariz.github.io/vibrant.js/ is then used to pick "prominent colors" from the image
* These are then the swatches displayed
Vibrant is a port of Android Palette (https://developer.android.com/reference/android/support/v7/g...), which specifically extracts colors it calls: "Vibrant", "Vibrant Dark", "Vibrant Light", "Muted", "Muted Dark", and "Muted Light".
I think this is why it also seems to create colors that don't appear to be related at times. I found the colors returned when searching for "black" and "white" particularly bizarre. "white" for example, gets what looks like a pure white image, but then has cyan and purple swatches: http://i.imgur.com/zlObSsB.png