Haven't heard of this technique, but apparently it uses two "frequencies"
of Gaussian blur to smooth a surface.  Also uses a high pass filter to
resharpen.  I'll follow up on this when time, as any technique to help
smooth a surface (not only skin) without giving that surface a tacky pasty
look would be worth investigating.

On Wed, Apr 29, 2015 at 3:55 PM, Geoff Thompson <[log in to unmask]>

>  Dear All,
>              Can anybody explain frequency separation in Photoshop? It's
> generally used for retouching faces without affecting colour underneath.
> I saw it demonstrated at a seminar by photographer Christian Fletcher.
>  I thought I could use
> it to put sharpening on another layer and indeed this works. I did this by
> deleting the blurred "Low" layer and applying sharpening on the frequency
> separation "Top" layer. This works and you can turn down the opacity of the
> sharpening or deep etch it. However the top layer is already sharpened by
> the process, resulting in over-sharpening if I use my usual smart sharpen
> and then unsharp mask. I gather this is to counteract the usual blurring?
> The process doesn't work if you don't blur the "Low" layer. If I knew what
> sort of sharpening the process applies perhaps I could compensate better.
> I'll send this to the list too.
> Thanks,
> Geoff
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Bruce Bartrug
Nobleboro, Maine, USA
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•The world is a dangerous place, not because of those who do evil, but
because of those who look on and do nothing.  - Albert Einstein
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