I’m really excited about my expanding photo retouching business. Learning more sophisticated editing techniques has been part of this effort so I can take on higher-end work. I’ve just been on a deep dive into Frequency Separation Retouching, coming’s up for air just long enough to write this post.
The most exciting retouching technique I have picked up is Frequency Separation. I’d heard of the technique and looked into it some time ago, but the internet is full of conflicting ideas about best practices (who would have guessed?) with the only agreement being that everyone is doing it wrong. And a vocal minority saying it shouldn’t be done at all. With all the misinformation, I never got my head around the technique. What a mistake!
Thanks to Joey Tichenor, a new photographer contact, I got an in-person workshop on how to use Frequency Separation. Turns out it is a viable technique. It was really helpful to watch someone assess an image and execute tasteful edits. The model didn’t look like she was make of Play-Doh when Joey got done. But the skin tones looked the way you’d expect a fashion photograph to look: subtly textured with even gradation from one tone to the next. Subtlety is your friend as these layers are very sensitive and its easy to overdo the effect.
Examples of before & after Frequency Separation editing below. This image is not edited any other way, what you see is the result of Frequency Separation only. That said, it could certainly use some other edits before I’d call it done!
How Frequency Separation Works
Frequency Separation is a clever hack of Layer Blending Modes that separates an image into two layers: a High Frequency layer that holds the texture, pores, whiskers and other details and a Low Frequency layer that holds large shapes and color. The High Frequency layer looks kind of like the result of a High Pass filter, holding mostly texture detail, see below. The Low Frequency layer is blurry, with large areas areas of color & tone, and no texture detail, see below.
When you need to edit texture without messing up subtle tonality you do that on the High Frequency layer, often with the clone stamp of Healing Brush. When you need to even out splotchy or abrupt tonality, make the edits on the low Frequency layer, often with a Gaussian Blur or Smudge Brush.
This technique is common in Beauty, Portraiture & Fashion photography, anywhere you see skin detail—especially women’s faces. It can also be adapted for Astrophotography. I’ve used it to preserve textures while making tonal edits in all kinds of images where traditional clone stamp & healing tools aren’t up to the task.
Take a look at the High Frequency layer above. This layer isolates the textural detail. Often the goal is to tame this textural detail, isolating it so that tonal edits don’t destroy it. You can use the High Frequency layer in non-obvious way that Joey showed me. By duplicating this High Frequency layer and masking it away except where you want to increase contrast, it’s possible to quickly add a very satisfying contrasty boost to particular details. Sort of like reversing the conventional Frequency Separation techniques. You can see this in the eye details of the after image above.