Here's a step-by-step guide on how to do frequency separation:
1. Duplicate the Background Layer (Twice):
* Select your "Background" layer in the Layers panel.
* Press Ctrl+J (Windows) or Cmd+J (Mac) twice to create two copies of the layer.
* Rename the top layer "High Frequency" and the layer below it "Low Frequency." This helps keep things organized.
2. Blur the Low Frequency Layer:
* Select the "Low Frequency" layer.
* Go to Filter > Blur > Gaussian Blur.
* Adjust the Radius slider until most of the skin's imperfections (large blemishes, uneven tones) are blurred, but you can still make out the general shape of the face. *A good starting point is often between 3-7 pixels, but it heavily depends on the resolution of your image.* You want to blur the color information without blurring the fine textures.
* Click OK.
3. Extract Texture Information for the High Frequency Layer:
* Select the "High Frequency" layer.
* Go to Image > Apply Image.
* In the "Apply Image" dialog box, set the following:
* Source: Your current document (the one you're working on)
* Layer: "Low Frequency"
* Blending: "Subtract"
* Scale: 2
* Offset: 128
* Invert: Make sure it is unchecked.
* Click OK.
* Change the Blending Mode of the "High Frequency" layer to Linear Light. You should now see the original image as it was before blurring.
4. Retouching the Low Frequency Layer (Color & Tone):
* Select the "Low Frequency" layer.
* Healing Brush Tool (J): Use this to blend out color variations, dark circles under eyes, redness, and general unevenness in skin tone. Set the Source in the options bar to "Sampled." Use a soft brush with low hardness and sample nearby areas (Alt+Click or Option+Click) to blend. Work carefully and in small increments. Avoid blurring essential features like the bridge of the nose or the lips.
* Clone Stamp Tool (S): Similar to the Healing Brush, use this to copy colors from one area to another. Lower the opacity to help create more subtle blending.
* Lasso Tool (L) + Gaussian Blur (Again): For larger areas of discoloration, select the area with the Lasso Tool, feather the selection a bit (Select > Modify > Feather - a radius of 5-10 pixels is often good), and then go to Filter > Blur > Gaussian Blur. Use a very small radius (0.5-2 pixels) to subtly even out the tone without blurring too much.
5. Retouching the High Frequency Layer (Texture):
* Select the "High Frequency" layer.
* Clone Stamp Tool (S): Use this tool to remove or minimize blemishes, pores, and fine lines. Sample from nearby areas with similar texture. Keep the opacity low (around 20-30%) to avoid creating obvious patches.
* Healing Brush Tool (J): Can be used similarly to the Clone Stamp, but often blends textures a little more. Experiment and see what works best.
* Spot Healing Brush Tool (J): Sometimes good for quickly removing very small blemishes. Be careful not to over-use it, as it can sometimes produce unnatural results.
6. Optional Adjustments:
* Frequency Separation with Layers Grouped: Group the "High Frequency" and "Low Frequency" layers into a folder (select both layers and press Ctrl+G/Cmd+G). You can then add layer masks to the group to apply the effects selectively.
* Opacity Adjustment: Adjust the opacity of the "High Frequency" layer to control the intensity of the texture. Lowering the opacity can sometimes result in a more natural look. You can also adjust the opacity of the entire layer group.
* Further Color Correction: Add adjustment layers (Curves, Levels, Color Balance, etc.) *above* the Frequency Separation layers to further refine the overall color and tone of the portrait.
* Sharpening: Add a *very* subtle sharpening layer *above* all other layers if needed (Filter > Sharpen > Unsharp Mask). Be careful not to over-sharpen, as this can exaggerate imperfections.
Tips and Considerations:
* Non-Destructive Editing: Work on duplicates of your original image and use layers and layer masks whenever possible. This allows you to make changes without permanently altering your original image.
* Resolution Matters: The Gaussian Blur radius values will vary significantly depending on the resolution of your image. A higher resolution image will require a larger radius.
* Subtlety is Key: The best retouching is often invisible. Aim for natural-looking results. Don't over-blur or over-smooth the skin.
* Practice Makes Perfect: Frequency separation takes practice to master. Experiment with different settings and techniques to find what works best for you and your style.
* Consider the Subject: Different subjects require different levels of retouching. A younger subject will likely need less retouching than an older subject.
* Avoid Over-Retouching: Over-retouched skin can look unnatural and plastic-like. Aim for a balance between smoothing and preserving natural texture.
* Soft Light Layer: Create a new layer set to Soft Light mode to dodge and burn areas that need more detail. This will create highlights and shadows that further emphasize certain areas.
Alternative Method Using Median:
Some photographers prefer using the Median filter instead of Gaussian Blur for the Low Frequency layer.
* Use the Median filter at (Filter > Noise > Median), adjusting the radius as needed (usually lower values than Gaussian Blur).
* The Apply Image settings remain the same.
The Median filter often preserves edges better, resulting in a slightly sharper image.
Troubleshooting:
* Skin looking too smooth/plastic: Reduce the opacity of the High Frequency layer or the entire layer group. Use smaller brush sizes and lower opacity when using the healing brush or clone stamp.
* Skin looking blurry: Reduce the Gaussian Blur radius on the Low Frequency layer.
* Halo effect: Make sure the "Scale" is set to 2 and "Offset" is set to 128 in the Apply Image dialog box. Also, feather the selection more when using the Lasso Tool.
By following these steps and tips, you can master frequency separation and achieve professional-looking portrait retouching results in Photoshop. Remember to practice and experiment to find the techniques that work best for you and your style. Good luck!