Constructing Gradient Map adjustment layers for use in luminosity masking. [details (http://www.retouchpro.com/tutorials/?m=show&id=132)]

Thank you -- I've always struggled with how Gradiant Maps work, and I'm sure I'm not alone in that. This tutorial is a great introduction to the subject!

Thank you for you excellent help in understanding gradient maps. I've used them for novelty items and abstract posterizations but had never thought of using them for what they were most likely really created for. Keep up the good work.

Thanks for the compliments. I noticed the tutorial didn't get a very high rating for clarity, so if anyone wants to point out parts that were unclear or confusing, I will rewrite them so they are more easily understood. Thanks.

Oh! I'm late to the party. Hope you don't mind a friendly bump.

I use G-Map black - white - white - black as shown in the tutorial as a tweakable alternative to Select > Colour Range. However, I also use Layer ChOps.

Let's say that you want to intersect R and G, but you want to convert greyscale to black-white-black as shown for a 'proper' selection.

Copy Red to Layers palette.
Give it a GMap Ad-Layer as shown by dpnew. I prefer to use a clipping group.
Copy Green of original photo to Layers palette.
On the Green copy in the Layers, clip another GMap Ad-Layer and use the black-white-black thing again.
Set the Green copy in the Layers to Multiply.

Tweak both GMaps to your heart's content.
When happy, Copy Merged and all that jazz.

I use this all the time for all kinds of things.
Like intersecting Sat with Lum.
Or Hue with Sat.

Of course, you don't have to use Multiply.
Multiply is an and operation (so to speak).
Whereas Screen is an or opertion (so to speak).
And then all of those other blending modes.

It's good stuff.