The frequency separation is one of the most used and effective techniques in beauty photo retouching (although you can use in many problems wrinkles in clothes, even tones etc …)
I personally usually use when I need to retouch major skin problems, in pictures beauty and close-ups that require perfect or publishers skin to remove those impossible wrinkles from clothes but this is a personal matter, once you control you’ll see how you can apply to many problems will try to explain how it is done and then I will put the link to a video in which you can see.
The frequency separation is, as the word implies, separate the image into two layers, one that we will keep texture information and one in which we are left with the color and volume information in order to work in them independently.
The way to do it is:
We opened our image
The we doubled twice so that we have the “background” layer and above it two copies which rename “high” and “low”
In the “Low” layer we need to apply a Gaussian blur of about 4px approx. (each image is a world ground blur gradually to lose all information and appreciate one color texture and volume)
In the “High” we will stop step manually by following these steps: Apply Picture → Picture → leave us the dialog box like this:
Where we will leave the settings shown:
Mark reverse the box
Ok mark and put the “High” layer blending mode to “Linear Light”
I make a folder with the two images which I call S & F and so have something more orderly workspace. From here we can start working on tweaking the texture layers (in the top) and volume / color (in the floor)
I leave a video which shows how to work in different layers,
to me personally I came in handy when I started in this world of photo retouching.
I hope you might help this little tutorial and if I can help you can contact you through a message on the web, mail, facebook etc …