A few weeks ago I was finishing up a batch of beauty edits for a skincare client and kept running into the same problem. The shots were technically clean, skin looked smooth, color was dialed in, but something was missing. Every image felt a little… flat. Like a drawing of a face rather than a face. I’d been so focused on removing imperfections that I’d accidentally ironed out the natural shadows and highlights that give skin its three-dimensional quality.

That’s the trap a lot of us fall into. We retouch toward smooth and end up with lifeless.

I went back to my reference folder and started watching tutorials. That’s when I landed on this one from Matt Kloskowski, which tackles exactly that problem using a smart, mask-driven approach to depth in Photoshop.

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Why Flat Portraits Happen in the First Place

When we retouch skin aggressively, especially using frequency separation or heavy healing work, we tend to even out the tonal variation across the face. That variation, the subtle play between lighter and darker areas, is exactly what makes skin look like skin and not vinyl. Shadows under the cheekbones, a slight brightness on the brow bone, the way light rolls off the tip of the nose. Remove too much of that and your subject starts to look like a wax figure.

Photographers who come from a studio background often dodge and burn by hand, painting light and shadow back in manually. That works, but it’s slow and requires a steady instinct for where light should fall. What Matt’s approach does is smarter. It uses the existing tonal information in the image as a roadmap.

Using Luminosity Masks to Target the Right Tones

The core of this technique is luminosity-based selection. Instead of painting depth in freehand, we’re letting Photoshop identify the highlights and shadows that already exist in the photo, then amplifying them selectively.

In the tutorial, Matt walks through accessing luminosity selections through the Channels panel. The idea is that Photoshop can build a selection based purely on the brightness values of the pixels. Bright areas get selected more heavily. Dark areas get selected less (or vice versa, depending on which channel you load). This creates a feathered, naturalistic selection that follows the actual contours of the light in your image rather than the edges of a brush stroke.

From there, he applies adjustments (Curves, specifically) to deepen the shadows and lift the highlights within those targeted areas. The key is subtlety. We’re not talking about dramatic contrast. We’re talking about 5 to 10 point nudges on the curve that compound across multiple tonal zones. Two or three of these layers, each targeting a slightly different luminosity range, build up into something that reads as genuine depth.

The Step-by-Step Workflow

Here’s how I’ve been applying this in practice after working through the tutorial:

First, flatten or stamp your retouched image to a new layer (Ctrl+Alt+Shift+E on PC, Cmd+Option+Shift+E on Mac). This gives you a clean starting point.

Open the Channels panel. Hold Ctrl (or Cmd on Mac) and click the RGB composite channel thumbnail. This loads a luminosity selection that favors the brighter tones in the image.

With that selection active, create a Curves adjustment layer. Photoshop automatically turns your selection into a mask. Now when you adjust the curve, only the highlighted areas respond fully. Pull the midpoint of the curve down slightly to add weight to the lighter areas without blowing anything out.

Invert the process for the shadows. Load the luminosity selection again, invert it (Ctrl+Shift+I / Cmd+Shift+I), and create a second Curves layer. This time, lift the shadows very gently to keep detail present in the darker zones, or push them down slightly if you want more contrast.

Repeat with a refined selection if needed. Matt emphasizes that the real power here comes from iteration. One mask might target the broad highlights. A second might target just the skin catchlights or the lightest parts of the forehead. Each layer is subtle on its own. Together, they create the illusion of dimension.

Label your layers clearly. I name all my Photoshop actions after movies, and I’ve started doing the same with layer groups. Right now my depth stack for a current project is called “Vertigo,” which feels appropriate given how disorienting it is when you toggle it on and off.

Where I’d Push This Further (and Where It Falls Down)

This technique works beautifully on well-lit studio portraits where there’s a clear light source to amplify. On flat, overcast, or ring-lit beauty shots, the luminosity information is already compressed, and the selections become harder to use without creating obvious banding or artificial contrast.

For those images, I’ll often combine this approach with a manual dodge and burn layer underneath, painting in just enough directional shadow to give the luminosity masks something to work with. Think of it as drawing the skeleton first, then letting the mask add the muscle. It’s a hybrid approach that takes longer but gives you more control on difficult light.

I’d also caution against using this on skin that hasn’t been retouched yet. Luminosity masks amplify everything in that tonal range, including texture, discoloration, and unevenness. Do your base retouching first, then add depth on top.

The One Thing to Hold Onto

Depth is not the same as contrast. You can add contrast to a flat image and make it look harsh. Adding depth means reinforcing the three-dimensional light that was already there, working with the image’s own tonal language rather than imposing something foreign on it.

Watch Matt Kloskowski’s full tutorial to see this technique in action with visual demonstrations that are genuinely hard to replicate in text. You can also find more of his work at mattk.com/art-of-masking.