Here's a step-by-step guide on how to do frequency separation portrait retouching:
1. Duplicate the Background Layer:
* Open your portrait image in Photoshop.
* Press Ctrl/Cmd + J twice to duplicate the background layer twice.
* Name the top layer "High Frequency" and the bottom one "Low Frequency." This helps you stay organized.
2. Blur the Low Frequency Layer:
* Turn OFF the visibility of the "High Frequency" layer (click the eye icon next to the layer).
* Select the "Low Frequency" layer.
* Go to Filter > Blur > Gaussian Blur.
* Adjust the Radius until the skin imperfections, blemishes, and fine details start to disappear, but the overall shape and tones are still visible. Start with a small radius (e.g., 2-5 pixels) and gradually increase it. The key is to blur the details away *without* blurring away the shapes.
* Click OK. The exact radius depends on the image resolution and the level of detail you want to separate.
3. Extract the High Frequency Layer:
* Turn ON the visibility of the "High Frequency" layer.
* Select the "High Frequency" layer.
* Go to Image > Apply Image.
* In the "Apply Image" dialog box, configure the settings as follows:
* Source: Select your Photoshop file name (the image you're working on).
* Layer: "Low Frequency"
* Blending: "Subtract"
* Scale: 2
* Offset: 128
* Invert: Unchecked
* Click OK. You should now see a mostly gray layer with fine details like pores and hair.
4. Change the Blend Mode of the High Frequency Layer:
* With the "High Frequency" layer selected, change its Blend Mode in the Layers panel from "Normal" to "Linear Light". This combines the High and Low Frequency layers to restore the original image appearance.
5. Retouching the Low Frequency Layer (Tones and Colors):
* Select the "Low Frequency" layer.
* Choose the Lasso Tool (L) or the Mixer Brush Tool (B).
* Lasso Tool: Create loose selections around areas with uneven skin tone (e.g., around blemishes, dark circles, or shadows). Then go to Filter > Blur > Gaussian Blur. Apply a *slight* blur (smaller radius than before, usually 1-3 pixels) to smooth out the tonal differences. Feathering the selection (Select > Modify > Feather) before applying the blur will help blend the edges of the selection.
* Mixer Brush Tool: (Recommended for more subtle and natural blending)
* Settings:
* Clean the brush after each stroke: Enabled (Checked)
* Load the brush after each stroke: Enabled (Checked)
* Wet: 1-10% (Low settings for subtle blending)
* Load: 10-20%
* Mix: 50-90% (Adjust for how much you want to blend)
* Flow: 5-20%
* Sample: Select "Sample All Layers" if you want to sample colors across layers. "Current Layer" is okay as well since you're mainly modifying tones.
* Use the Mixer Brush to gently paint over areas of uneven skin tone, sampling the colors from the surrounding skin. Use short, smooth strokes, following the natural contours of the face.
6. Retouching the High Frequency Layer (Details):
* Select the "High Frequency" layer.
* Use the Clone Stamp Tool (S) or the Healing Brush Tool (J).
* Clone Stamp Tool: Set the Opacity to a low percentage (e.g., 10-30%). Alt-click (Option-click on Mac) to sample a clean area of skin and then paint over blemishes, scars, or other imperfections. Be careful not to overdo it, as removing too much detail can make the skin look unnatural.
* Healing Brush Tool: Similar to the Clone Stamp Tool, but it blends the sampled texture with the surrounding area, making it a bit more forgiving.
* Important: When retouching the High Frequency layer, focus on removing or minimizing imperfections while preserving the skin's texture (pores, fine lines). Over-smoothing this layer will make the skin look plastic-like.
7. Review and Refine:
* Zoom in and out to check your work.
* Adjust the opacity of the "High Frequency" or "Low Frequency" layers if you want to fine-tune the overall effect.
* If you've blurred too much in the "Low Frequency" layer, you can add a bit of sharpness back in by using the Unsharp Mask filter (Filter > Sharpen > Unsharp Mask) on the "High Frequency" layer. Use very conservative settings.
Tips and Best Practices:
* Non-Destructive Editing: Consider using adjustment layers (e.g., Curves, Levels) for overall tone and color corrections *before* starting frequency separation. That way, any corrections you make will apply to the entire image. Also, using the Healing Brush Tool or Clone Stamp Tool on a new, empty layer above the "High Frequency" layer can provide a non-destructive way to retouch.
* Work at High Resolution: Frequency separation works best with high-resolution images. This allows for more precise editing and prevents pixelation.
* Be Subtle: The goal is to enhance the portrait, not to completely erase the person's natural features.
* Avoid Over-Smoothing: Over-smoothing the skin is a common mistake. Preserve the natural texture for a more realistic result.
* Use Layer Masks: If you've made changes to the "Low Frequency" layer that affect areas you didn't intend to (e.g., blurring into the hair), use a layer mask to selectively apply the effect only to the skin.
* Experiment: The best settings for frequency separation will vary depending on the image. Experiment with different blur radii and blending techniques to find what works best for you.
* Facial Structure and Light: Pay attention to the underlying facial structure and the direction of the light. Don't flatten the highlights and shadows.
* Zoom level: For retouching work, it is best to zoom to 100% or 50% view. This allows you to see the details accurately.
Example Workflow:
1. Initial edits in Camera Raw or Lightroom (exposure, white balance, basic color corrections).
2. Open image in Photoshop.
3. Duplicate background layer twice (Low Frequency, High Frequency).
4. Gaussian Blur on Low Frequency layer (radius 2-5 pixels, adjusted as needed).
5. Apply Image to High Frequency layer (Subtract, Scale 2, Offset 128).
6. Linear Light blend mode on High Frequency layer.
7. Mixer Brush on Low Frequency layer for tonal blending.
8. Clone Stamp or Healing Brush on High Frequency layer for detail removal.
9. Final adjustments (sharpening, color grading) as needed.
Frequency Separation is a time-consuming technique, but the results can be worth it. With practice, you'll develop your own workflow and be able to achieve stunningly natural-looking portrait retouching.