How to extract a single color?

[Krayne CG]

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?

[Jeff Arola]

While there are a multitude of ways to accomplish what you ask including actions, plugins, etc i'll show you but one.

The below steps remove the white leaving the red.

1. duplicate the layer

2. put a color fill layer set to black below the duplicated layer

    (Layer>New Fill Layer>Solid color)

3. go to the Channels panel and Ctrl click on either the Blue or Green channel which gives you a selection of the white

4. go to Select>Inverse to inverse the selection

5. go to the Layers panel then to Layer>Layer Mask>Reveal Selection

    or press the Add Layer Mask at the bottom of the Layers panel

6. put a blank layer below the layer you just added the layer mask to

7. merge the blank layer and layer with the layer mask by making the layer with the layer mask active then pressing Ctrl+E

8. go to Layer>Matting>Remove White Matte

[Krayne CG]

Thanks! That worked great!  I had to do it twice with my work to get all of the white out, but it did work.
Is there a simpler way to do it, or is that way the best?

[Krayne CG]

Also, how might I do that with a color that isnt R G or B?

[c.pfaffenbichler]

The Blend Mode »Linear Burn« might help.