Here's a step-by-step guide on how to do frequency separation portrait retouching in Photoshop:
1. Duplicate the Background Layer:
* Open your portrait image in Photoshop.
* In the Layers panel (Window > Layers), select the "Background" layer.
* Press Ctrl/Cmd + J twice to duplicate the background layer two times. Rename these layers for clarity:
* Top Layer: "High Frequency" (or Texture)
* Middle Layer: "Low Frequency" (or Tone/Color)
* Bottom Layer: "Background" (Leave untouched as a backup)
2. Prepare the Low Frequency Layer (Blur):
* Turn off the visibility of the "High Frequency" layer by clicking the eye icon next to it.
* Select the "Low Frequency" layer.
* Go to Filter > Blur > Gaussian Blur...
* Determine the Blur Radius: This is the most crucial part. You need to blur the details so that the texture (pores, fine lines) disappears, but the underlying tonal information (color transitions, light and shadow) remains visible. Start with a small radius (e.g., 2-3 pixels). Increase the radius until you can no longer easily see the skin pores and small details. Don't over-blur; the goal is to blur the *texture*, not the form. A good range is usually between 2 and 8 pixels, but it depends on the image resolution and how much detail is present.
* Click OK.
3. Prepare the High Frequency Layer (Details):
* Turn on the visibility of the "High Frequency" layer.
* Select the "High Frequency" layer.
* Go to Image > Apply Image...
* Apply Image Settings: This step effectively subtracts the blurred "Low Frequency" layer from the "High Frequency" layer, isolating the texture details.
* Source: Choose the current image name (your portrait image file).
* Layer: Select the "Low Frequency" layer.
* Blending: Set this to Subtract.
* Scale: Set this to 2.
* Offset: Set this to 128. (This is crucial for proper separation.)
* Invert: Make sure it's *not* checked.
* Click OK.
* Change Blend Mode: Change the blend mode of the "High Frequency" layer to Linear Light. This blends the texture details with the underlying tonal information.
4. Retouching the Low Frequency Layer (Tonal Corrections):
* Select the "Low Frequency" layer. This is where you'll work on smoothing out skin tones and reducing blemishes.
* Choose your Retouching Tool: Here are a few popular choices:
* Mixer Brush Tool (B): A favorite for seamless tonal blending. Experiment with different settings:
* Clean the brush after each stroke: Checked is often better.
* Sample All Layers: *Unchecked*. This ensures you're only blending the colors within the Low Frequency layer itself.
* Wet, Load, Mix, Flow: Experiment. Low Wet (5-10%), Load around 5-10%, Mix around 80-90%, Flow around 5-10% is a good starting point.
* Opacity: Use a low opacity (5-15%) for subtle blending.
* Clone Stamp Tool (S): Use with *low opacity* (5-10%) and a soft brush to sample clean skin and carefully clone over blemishes. Set the "Sample" option to "Current Layer" so it only samples from the Low Frequency layer.
* Healing Brush Tool (J): Similar to the Clone Stamp, but blends the copied pixels with the surrounding area. Use with caution, as it can introduce unwanted texture from other parts of the image if used too aggressively. Set the "Sample" option to "Current Layer".
* Lasso Tool (L) + Gaussian Blur: Select small areas with uneven skin tone using the lasso tool (feathering set to 5-10px), then apply a *very slight* Gaussian Blur (Filter > Blur > Gaussian Blur) of 1-2 pixels. This is a more aggressive smoothing technique and should be used sparingly.
* Retouching Process:
* Zoom in to areas with uneven skin tone, blemishes, or dark spots.
* Carefully blend or clone using short, light strokes. Avoid large, sweeping motions, which can create unnatural blurring.
* Work slowly and subtly. It's better to make many small adjustments than a few large ones.
* Focus on blending the color and light transitions. You're trying to even out the skin tone, not remove texture entirely.
* Periodically zoom out to assess your progress and make sure the skin looks natural.
* Addressing Blemishes: Gently smooth the tones around the blemish. For larger blemishes, a small amount of cloning with the clone stamp tool is often necessary.
5. Retouching the High Frequency Layer (Texture Refinement - optional and VERY CAREFULLY):
* Select the "High Frequency" layer.
* Caution: This layer contains the skin's texture. Retouching here can easily lead to an unnatural, plastic look if you're not careful. *Most of the time, you won't need to do much on this layer.*
* Spot Healing Brush Tool (J): *Very lightly* remove stray hairs or minor imperfections that are primarily texture-based. Set the "Sample" option to "Current Layer".
* Healing Brush/Clone Stamp Tool: Use very sparingly and with *very low opacity* (1-5%) to subtly soften harsh texture details. Again, set the "Sample" option to "Current Layer".
* Dodge and Burn (Optional, very cautiously): You can very subtly dodge (lighten) and burn (darken) certain areas of texture if needed, but be very careful not to overdo it. Use a very soft brush and low opacity.
6. Global Adjustments (Optional):
* Once you're happy with the retouching, you can add adjustment layers above all other layers to fine-tune the overall look:
* Curves: Adjust overall brightness and contrast.
* Color Balance: Adjust skin tone.
* Hue/Saturation: Subtly adjust color saturation.
Tips and Best Practices:
* Non-Destructive Editing: Frequency separation itself is non-destructive (you're working on copies of the original layer). Always use adjustment layers for final color and tone corrections so you can easily modify them later.
* Zoom Levels: Retouch at 100% zoom for detail work, but frequently zoom out to assess the overall effect.
* Brush Hardness: Use a very soft brush (0% hardness) for all retouching tools. This helps to blend the edits seamlessly.
* Opacity/Flow: Keep the opacity and flow of your brushes low (5-15%) for gradual, subtle changes.
* Start Subtle: It's easier to add more retouching than to remove it.
* Don't Overdo It: The goal is to enhance the portrait, not to create a completely artificial look. Preserve natural skin texture and avoid making the skin look waxy or plastic.
* Practice Makes Perfect: Frequency separation takes practice to master. Experiment with different settings and techniques to find what works best for you.
* Resolution Matters: Frequency Separation works best on high-resolution images. Lower-resolution images may not have enough detail to effectively separate the frequencies.
* Dodge & Burn after Frequency Separation (if needed): Dodge & Burn is often done *after* frequency separation to enhance highlights and shadows without affecting the texture.
Troubleshooting:
* Unnatural/Plastic Look: You've likely over-blurred the Low Frequency layer, overworked the High Frequency layer, or used too strong of a brush setting. Reduce the blur radius, tone down your retouching, and lower the brush opacity/flow.
* Visible Artifacts: This can happen if you use the clone stamp tool too aggressively on the Low Frequency layer. Try using the Mixer Brush Tool instead, or reduce the clone stamp's opacity.
* Texture Disappears: You've probably over-blurred the Low Frequency layer. Reduce the blur radius.
* Not enough smoothing: Increase the blur radius on the Low Frequency layer, but be careful not to overdo it.
In Summary:
Frequency separation is a powerful technique, but it requires patience and a subtle hand. By carefully separating tonal information from texture, you can achieve incredibly natural-looking portrait retouching results. Remember to practice and experiment to find the settings and techniques that work best for you and your images.