It is well known that frequency spearation is a technique to retouching skin in Portaits. There are a lot of PhotoShop tutorials about it.
One layer with gaussian blur and one above with linear light... but what would be the equivalent of "Apply Image" (used in Photoshop) in PhotoPaint, and what values should I use? (Preferably on the 2017 version)
For those who do not know what frecueny separation is www.google.com/search
Since every image is different, it will take a different approach to each image. I have another Frequency Separation (F.S.) system that I use that involves layers similar to Photoshop using Lightness and Color.
Original image here...
If I may ask Mike, What is that system?
I create a color layer and a Lightness layer independent of each other. Creating these layers is simply by overlaying the original images over a white background and using the blend modes mentioned.