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Photoshop: Portrait Retouching through Frequency Separation
Iain Anderson on Sat, September 26th 1 comments
Photoshop has a bunch of important, but lesser well-known hidden commands and functions. Here, Iain Anderson shows how to Photoshop skin tone and smoothness using frequency separation.

It’s rare that the name of an app is verbed (remember: Verbing Weirds Language!) but Photoshop has indeed received this honor. The line “Seriously? It’s like you’re Photoshopped!” from Crazy, Stupid, Love is just one example of how ubiquitous this app has become in the realm of image manipulation. Other apps can do a lot of what Photoshop does, but for the experienced user, nothing else is quite good enough. In this article, we’ll take a look at how to use long-hidden commands to correct images in a unique and very effective way. We’ll be smoothing skin for that “magazine cover” perfected look. 

An original photo of the author, featuring crazy hair and worse.

An original photo of the author, featuring crazy hair and worse.

 

Getting Started

Start with a relatively close-up portrait photograph, then press Command-J a couple of times to create two duplicates of this layer. Rename the two layers, to “high” on top and “low” beneath it. These two layers will separate, to represent the fine skin detail (high) and the general light and shade (low). Breaking them apart means we can adjust the light and shade without destroying skin detail, and we can remove spots and blemishes without worrying about the brightness levels. 

First, create two duplicate layers.

First, create two duplicate layers.

 

The Method 

Hide the “high” layer, then select the “low” layer. Choose Filter > Blur > Gaussian Blur, and push the slider up until the skin looks smooth, but the face is still recognizable. For an 18MP image, this will be 20-30px. 

Apply this to the “low” layer.

Apply this to the “low” layer. 

Show the “high” layer, make it visible again, then choose Image > Apply Image and then choose “low” as the Layer, then Subtract for the Blending. Set Scale to 2, and Offset to 128. This is the texture layer, and will look mostly grey with visible edges. 

Apply this to the “high” layer.

Apply this to the “high” layer.

Press OK, and back in the main image, set the blend mode for the “high” layer to Linear Light. The image should be back to normal. Shown together, the high and low layers create an image identical to the original, but we can adjust light and shade on the low layer, and detail on the high layer. 

Layers should now look like this, but the image will look the same as before.

Layers should now look like this, but the image will look the same as before.

  

Smoothing Out the Light and Shade

Leaving high and low layers visible, select the “low” layer, then choose the Lasso Tool. Set Feather to around 30 in the Control Panel at the top, then select an area of skin you’d like to smooth out, somewhere where the light and shade aren’t as seamless as you’d like. With the selection active, choose Filter > Blur > Gaussian Blur, and choose a much higher amount, around 50px, until you see the light become even. Press OK.

Original on the left, smoothed shadows on the right.

Original on the left, smoothed shadows on the right.

Repeat, selecting each area you’d like to smooth, then pressing Command-F to repeat the blur each time. This is all about selective contrast reduction, evening out the light, and a large part of what makeup and lighting help with. It’s also quite different from what you can do with the Healing or Spot Healing tools.

A finished “low” layer.

A finished “low” layer.

  

Removing Blemishes

Now for something a little more traditional, though. Choose the Clone Stamp tool, make sure it’s set to work on the Current Layer only, and select the “high” layer. Option-click on a clean area of texture, then paint over any unwanted spots, freckles or stray hairs. You don’t need to worry about the lightness because you’re only cloning texture, and feel free to repeatedly Option-click-then-paint until the image is cleaned up. That’s it for the retouching pass, but if you want to add adjustment layers on top to affect the overall light and shade, go ahead.

A finished “high” layer.

A finished “high” layer.

 

Conclusion

As with any retouching task, it’s easy to take it too far, so if you’d prefer a more subtle effect, put both layers into a group, then turn the group’s opacity down. But overall, this is a great technique for producing that “film star” look without a make-up and lighting team on standby. It’s not real, but it’s not too fake either. Use it wisely.

The completed image, without taking things too far.

The completed image, without taking things too far.

Comments (1)

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  • Iain Anderson
    Author here. Worth noting: Affinity Photo has a dedicated Frequency Separation tool, so you wouldn't follow all these steps with that app.
    • 4 years ago
    • By: Iain Anderson
    Reply
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