1. Duplicate Your Layer:
* This is the foundation of frequency separation. It ensures you're working non-destructively.
* Select your background layer (the image you want to retouch).
* Press `Ctrl+J` (Windows) or `Cmd+J` (Mac) twice. This creates two copies of your background layer.
* Rename the top layer to "High Frequency" or "Details".
* Rename the bottom copy to "Low Frequency" or "Color/Tone".
2. Blur the Low Frequency Layer:
* Select the "Low Frequency" layer.
* Go to `Filter > Blur > Gaussian Blur`.
* Adjust the `Radius` slider. The goal is to blur the details of the skin (pores, fine lines) enough so that they're no longer prominent, but you can still see the overall shape. A good starting point is usually between 3-7 pixels, but it heavily depends on the image resolution and how close you are zoomed in.
* Zoom in to 100% to accurately assess the blur.
* Click "OK".
3. Extract the High Frequency Layer:
* Select the "High Frequency" layer.
* Go to `Image > Apply Image`. This is the key step in mathematically extracting the details.
* Settings in the Apply Image dialogue:
* Source: Make sure it's your active document.
* Layer: Select the "Low Frequency" layer (the one you just blurred).
* Channel: Select "RGB" (unless you're working on a specific color channel for a specialized purpose).
* Blending: Choose "Subtract". This is crucial.
* Opacity: Set to 100%.
* Preserve Transparency: Uncheck.
* Mask: Leave unselected.
* Scale: Set to 2. This compensates for the "Subtract" blend mode darkening the image.
* Offset: Set to 128. This centers the values around neutral gray, allowing for both adding and subtracting detail.
* Click "OK".
* Now change the blend mode of the "High Frequency" layer to Linear Light. This will reveal the extracted details. If you see a gray layer, you have likely missed setting the correct "Scale" and "Offset".
4. Retouching the Low Frequency Layer (Smoothing Skin Tone):
* Select the "Low Frequency" layer.
* Option 1: Mixer Brush Tool (Recommended)
* Select the `Mixer Brush Tool` (found under the Brush tool).
* In the options bar at the top, set the following:
* Clean the brush after each stroke: Click the button that looks like a brush cleaning itself. This prevents color smudging.
* Sample All Layers: *Important*. Make sure this box is *unchecked* if you want to work solely on the current layer. Checking it will incorporate information from the High Frequency layer, defeating the purpose.
* Wet: Adjust to around 10-20%. Controls how much paint is loaded onto the brush.
* Load: Adjust to around 10-20%. Controls how much paint the brush picks up from the canvas.
* Mix: Adjust to around 70-90%. Controls how much the loaded paint mixes with the canvas.
* Flow: Adjust to around 10-20%. Controls how much paint is applied with each stroke.
* Sample the colors on the skin by alt-clicking (Option-clicking on a Mac) and gently paint over areas with uneven skin tones. Use short, light strokes, following the contours of the face. Think of "sculpting" the light on the skin. *Don't overdo it!* The goal is to smooth, not create a plastic or blurry look.
* Vary the brush size as needed using the `[` and `]` keys.
* Zoom in and out to see the overall effect.
* Option 2: Blur Tool (Less Recommended)
* You *can* use the `Blur Tool` (found under the Sharpen Tool), but it's generally less precise and can easily lead to a blurry, unnatural look. If you use it, keep the `Strength` very low (around 10-20%) and use short, light strokes.
* Option 3: Lasso Tool and Gaussian Blur (A faster option, but less precise)
* Use the Lasso Tool (L) to make selections around areas of uneven skin tone.
* Go to `Filter > Blur > Gaussian Blur`.
* Use a very small radius (1-3 pixels) to blend the selected area. Be careful not to over-blur!
5. Retouching the High Frequency Layer (Removing Blemishes and Imperfections):
* Select the "High Frequency" layer.
* Option 1: Clone Stamp Tool (Recommended for blemishes)
* Select the `Clone Stamp Tool` (S).
* In the options bar, make sure `Current Layer` is selected from the "Sample" dropdown (important!). This means the tool will only sample from the "High Frequency" layer.
* Alt-click (Option-click on a Mac) on a clean area of skin *very* close to the blemish to select the source.
* Click on the blemish to clone the clean skin over it. Work in small increments.
* Change the source frequently to avoid repeating textures.
* Option 2: Healing Brush Tool
* The `Healing Brush Tool` (J) can also be used, but it's often better for larger areas. Make sure `Current Layer` is selected in the options bar.
6. Refinements and Considerations:
* Opacity Adjustment: After retouching, adjust the opacity of either the "Low Frequency" or "High Frequency" layers to fine-tune the overall effect. If you've over-smoothed the skin, reduce the opacity of the "Low Frequency" layer. If you've removed too much detail, reduce the opacity of the "High Frequency" layer.
* Frequency Separation Group: Create a group for your "Low Frequency" and "High Frequency" layers (select both layers, then `Ctrl+G` or `Cmd+G`). This allows you to easily turn the effect on and off to compare the before and after. You can also adjust the opacity of the group to control the overall strength of the frequency separation.
* Masking: Use layer masks on the "Low Frequency" and "High Frequency" layers to target specific areas. For example, you might mask out the eyes, lips, and hair from the "Low Frequency" layer to avoid softening them.
* Don't Overdo It! The key to good portrait retouching is subtlety. Avoid making the skin look plastic or unnatural. Step away from your screen periodically to get a fresh perspective.
* Resolution Matters: The higher the resolution of your image, the more precise you need to be with your blur radius and retouching.
* Alternative to Apply Image: Using a High Pass Filter: You can use a High Pass filter to extract the High Frequency layer. Duplicate the original layer, then apply Filter->Other->High Pass. Set the radius just high enough to see the details (like blemishes) and set the blend mode to Linear Light. Then duplicate the original again and apply a Gaussian Blur as in step 2. Put all layers in a group. This method allows you to adjust the blur amount and detail level without needing to redo the subtraction calculations.
Example Workflow:
1. Open your portrait.
2. Duplicate the layer twice, naming them "High Frequency" and "Low Frequency".
3. Blur the "Low Frequency" layer with a Gaussian Blur (e.g., Radius of 5 pixels).
4. Select the "High Frequency" layer and use `Apply Image` with the settings described above. Set the blend mode to Linear Light.
5. Select the "Low Frequency" layer and use the Mixer Brush Tool to smooth skin tones.
6. Select the "High Frequency" layer and use the Clone Stamp Tool to remove blemishes.
7. Adjust layer opacities and masks as needed.
Troubleshooting:
* Gray Layer After Apply Image: You likely missed the "Scale" and "Offset" settings in the `Apply Image` dialog box. Double-check that they are set to 2 and 128, respectively. Also, ensure you have the Linear Light blending mode set on the High Frequency layer.
* Skin Looks Too Blurry: Reduce the radius of the Gaussian Blur on the "Low Frequency" layer. Also, make sure you're not over-smoothing with the Mixer Brush Tool or Blur Tool.
* Skin Looks Unnatural/Plastic: You're likely overdoing it. Reduce the opacity of the "Low Frequency" layer or the entire frequency separation group. Use a lighter touch with your retouching tools.
* Pores are Disappearing: You are probably blurring the "Low Frequency" layer too much, or are blending too much with the Mixer Brush. Reduce the blur radius, or reduce the brush's Mix setting.
* Retouching Affecting Other Areas: Use layer masks to isolate the areas you want to retouch.
Frequency separation takes practice, but with a little patience, you can achieve professional-looking portrait retouching results. Remember to work subtly and focus on enhancing the natural beauty of your subject.