Normal Displacement...?

Some of you may be familiar with this fr om Photoshop, where it is possible to create color displacement maps (which use the red and green channels for displacement, ignoring the blue), that kind of resemble normal maps...

I know the same thing can be done in FF by extracting the right color channels from an image and then running them thru a Lookup. I just wondered if anyone can think of examples wh ere this technique has been used in a filter.

I know the forum doesn't see much use, so I don't expect any response to come quickly, but I'm throwing this out there anyway, on the chance someone knows and doesn't mind pointing out such filters.

Thanks in advance! TTFN