How to extract a single color?
I have an image that has both greyscale and colored portions that to some extend blend together with each other. How would I extract just the Red information? For examply, go from this:

to this:

The above images came from a layered psd where I just turned off the white layer. But if an image is completely flat, is it even possible to do something like that? I've already tried using hue/sat, color balance and channel mixer but I couldn't find a way to remove the white from the red.
Problem is is that white contains all the channels, so no matter how I mix them out Im still left with the white, exerpt its red now. Is there a "smarter" way to do this?
