Frequency separation

Lately I have been investigating the prospects of frequency separation. Experimenting with the high pass filter in Photoshop for sharpening, inverting the layer to soften. As usual there are at least ten ways to do any single thing in Photoshop, which leads me around looking for one that can fit my workflow, and this approach by Natalia Taffarel seems like it holds potential.

The idea is basically that you can separate each image into separate layers holding texture and colour tones; with that you can then make adjustments to texture without affecting tones and vice versa. If this all sounds greek, don't worry, you're not alone. It took me quite a while to even start getting my head around it, but I feel the image of Albert Einstein/Marilyn Monroe in the above link shows the concept far better than I can explain it...

Picture at the top is from a portrait shoot I did some time ago that I thought would be good to practice on.