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The key point in this method (which isn't actually that new or innovative, I think I first read about it in a White Dwarf some 10 years ago) is getting camouflage tones which are relatively close to each other, but still provide "area contrast". Also, hard edges between different tones are softened to provide a gradually darkening "border area" instead.
I believe the term is called "filtering" or something like that. I know MIG has a pretty good article or three on the topic online. :-)Grimm