There has been much talk in retouching circles lately about frequency separation. If you Google that phrase a plethora of tutorials will turn up. Most of these tutorials run the same route - separating the image into high- and low-frequency layers, then painstakingly brushing out flaws and imperfections.
The results are spectacular. But most of the time, you may not have the patience, or the luxury, to execute frequency separation. Unfortunately, at the other end of the spectrum are techniques that call for merely blurring the image and blending with Overlay or Soft Light. This often results in plasticky-looking skin, or a model which looks more like a Barbie doll than a real human being!
This technique is a hybrid in that it calls for a rarely-used filter and a couple of extra steps, but I think the results speak for themselves. The technique itself is quite quick to do, and as an added advantage, it will work on both sexes!:
Begin with the model - this one is from FreeImages (http://www.freeimages.com/photo/764724).
Duplicate the Background layer and erase away everything that will not be affected by the smoothing process.
(Quick tip: to make the erasing process less tedious, hide the original Background, use the Lasso tool to select the portions that will not be smoothed, apply a small Feather, then delete it. You can then use the Eraser tool to quickly finish off - the completed erasure should look somewhat like a theatrical mask.)
Apply a High Pass filter - Filter > Other > High Pass...
(Note: this filter is often used in filmography as a method of sharpening images.)
In the filter dialog, increase the Radius till you see a distinct edge:
- for this model we used 8, the number will vary depending on the image.
From the Image menu, select Invert from the Adjustments submenu - this will reverse the image.
(Explanation: You may be wondering - why did we Sharpen then reverse the sharpening? Why not just soften it with a blur, like Gaussian Blur? That is exactly what we want to avoid. Gaussian Blur, or any of the Blurs for that matter, make the image too smooth and even. The result? -the model looks like a Barbie doll.)
To complete the technique, change blending mode of the duplicate ("mask") layer to Overlay and lower the Opacity till the skin is smooth but still retains its texture - for most images, an Opacity ranging between 55% - 85% should do the trick.
And that's it!