Frequency separation allows you to retouch images by editing one aspect without affecting others. For example, it will allow you to soften the skin while maintaining its texture. Here’s a 21-minute video by PiXimperfect on how to use this advanced technique to improve your retouching skills.
“We are going to start off by understanding the basic principles of Frequency Separation and why to use it as a technique and what advantages it has,” says instructor Unmesh Dinda. “Firstly, we’ll learn what is Frequency and how is it related to images.
“Then, we’ll move on to learn how to separate different frequencies in an image to target the skin texture and the color separately. After that, we will really go in-depth into what is mixer brush and how to use it in this technique. Also, I’m going to share my favorite tips and tricks to get the softening done faster, finer, and easier.”
Frequency separation works on the fact that different colors have different frequencies. That means that you can isolate certain parts of an image from another, separating details and smoother areas from each other. Then, with some Photoshop wizardry, you can work to subtract one part you’ve isolated from another.
Ultimately, you’re left with two layers. One will contain the details and texture, the other the colors. The latter is what you use to smooth out the light and soften the skin.