Start by building an observation group that exposes every flaw, then split the image into low and high frequency: low frequency carries light and color, high frequency carries texture and detail. Handled separately they never interfere, and that is the proper route to skin retouching — learn it in Online PS and it pays off for a long time.
Build an observation group to exaggerate the flaws
An observation group removes color distraction so blemishes in skin tone and luminance are exposed, which makes them easier to fix.
- Add a Black & White adjustment layer to convert the image to greyscale.
- Add a Curves adjustment layer and pull an S-curve to boost contrast, so flaws stand out more.
- Group the two adjustment layers and name the group "Observation". You can toggle its visibility at any point while retouching to check your work.
Separate low and high frequency
The core step — peeling texture away from light and shadow. Make sure the values are exact.
- Rasterize the background layer (if it is a smart object), then press
Ctrl+Jtwice for two copies. Name them "Low" and "High". - Hide "High" and select "Low". Run Filter > Blur > Gaussian Blur with a radius just large enough to erase skin texture (about 6‑10 px).
- Show and select "High". Run Image > Apply Image: Layer "Low", Blending "Subtract", Scale 2, Offset 128. Click OK, then change that layer's blending mode to Linear Light — the image returns to its original appearance and the separation is complete.
Work the low frequency layer: even out the light
Soften the color blocks and light transitions on the low layer so the skin becomes flat and clean.
- Select the "Low" layer and use the Mixer Brush tool (Wet 30%, Mix 60%, Flow 20%), painting along the facial structure to blend the color transitions.
- You can also run Surface Blur on a skin selection (radius and threshold around 10) for a more even result.
- Use a layer mask to protect the eyes, brows and lips — anything that needs to stay sharp.
Work the high frequency layer: remove blemishes
Repair spots and pimples on the high layer; because the texture is isolated, the retouching won't disturb the existing light.
- Select the "High" layer. Use the Patch tool to circle a spot and drag it onto clean texture to replace it.
- Use the Clone Stamp tool (opacity 40%) for fine lines, sampling from similar texture.
- For more flexibility, use the Healing Brush on a blank layer with "Sample All Layers" ticked.
Overall adjustment and polish
With the core work done, finish with a final pass that gives the skin a translucent quality.
- Hide or delete the observation group. The skin is now smooth but still has real texture.
- Create a new layer and run Filter > Other > High Pass (radius 1 px), then set the blending mode to Soft Light to bring detail back.
- Add a Curves adjustment layer to lift the midtones so the skin looks translucent.
- To unify skin tone, nudge it with Selective Color (reduce black in the reds and yellows).
Advanced retouching tips
- Frequency separation takes repetition to get comfortable with. Early on, try the simplified version: blur only the low layer and paint the important areas back with a mask.
- Avoid over-blurring the low layer or you lose three-dimensional form; don't over-repair the high layer either, or texture disappears.
- Compare against the original often while you work, so over-retouching doesn't produce that plastic look.
- Online PS (www.zaixianps.cc) fully supports layers, blending modes, adjustment layers and professional filters, so the frequency separation workflow is entirely possible — and there is nothing to install, it's ready the moment you open it.
- Once you have frequency separation down, move on to Dodge & Burn and neutral grey retouching for commercial-grade light shaping.