Confused

I purchased this so that I could pull one color out of a picture. I want to take a picture and just have one color be shown, Purple, Red, Blue, etc and the rest of the picture be black and white - does not really seem that is what you can do. Am I missing something here. FX Studios have things called Red and Blue Stroke that does the exact same thing, but I was looking to do that with a few more colors. Any suggestions on how to do that??

Scalise4 about ColorStrokes