1. Preparation:
* Open your image: Load the portrait you want to retouch in Photoshop.
* Duplicate the Layer (Twice): Press `Ctrl+J` (Windows) or `Cmd+J` (Mac) twice to create two copies of your background layer. This gives you a solid base to work non-destructively.
* Rename the Layers: Rename the top layer "High Frequency" and the bottom layer "Low Frequency". This helps you keep track of which layer you're working on.
* Turn off the visibility: Turn off the visibility of the "High Frequency" layer by clicking the eye icon next to its name in the Layers panel.
2. Creating the Low Frequency Layer:
* Select the "Low Frequency" layer: Click on the "Low Frequency" layer to make it active.
* Apply Gaussian Blur:
* Go to `Filter > Blur > Gaussian Blur`.
* Crucial Step: Determine the Blur Radius: This is the most important part. You want to blur the layer just enough so that the skin imperfections are still visible, but softened and without losing major facial contours. Start with a small radius (around 2-4 pixels) and gradually increase it while watching the image. Zoom in to 100% to get a good view. The goal is to remove small details and merge the tones together.
* Click "OK".
3. Creating the High Frequency Layer:
* Select the "High Frequency" layer: Click on the "High Frequency" layer to make it active.
* Turn the visibility back on: Turn the visibility of the "High Frequency" layer back on by clicking the empty box next to its name.
* Apply Image:
* Go to `Image > Apply Image`. This opens the Apply Image dialog.
* Configure the Apply Image Settings:
* Layer: Choose the "Low Frequency" layer.
* Blending: Set to "Subtract".
* Scale: Set to "2".
* Offset: Set to "128".
* Channel: RGB is the typical channel to select.
* Click "OK". You'll likely see a mostly gray image. This is correct.
* Change Blending Mode:
* In the Layers panel, change the blending mode of the "High Frequency" layer from "Normal" to "Linear Light". This will reveal the original image.
4. Retouching the Low Frequency Layer:
* Select the "Low Frequency" layer.
* Tools to use: Choose one of the following tools:
* Mixer Brush Tool (Recommended): This is generally the best tool for frequency separation.
* Select the Mixer Brush Tool (looks like a paintbrush with a droplet).
* In the options bar at the top, set the following:
* Clean the brush after each stroke: Check this box to prevent color bleeding.
* Wet: Adjust based on the size of the area you need to blend (2-15%). Smaller areas will require lower percentage.
* Load: How much color the brush will take from the area you're painting. Generally 10-20% is good, but may need adjusting based on image.
* Mix: How much the color from the area you're painting will be mixed into other areas. Start with 70-90% and adjust if needed.
* Flow: Start with 5-10% for gradual changes.
* Sample All Layers: Make sure this is unchecked. You *only* want to sample from the Low Frequency Layer.
* Gently paint over areas with uneven skin tones, blending the colors together. Use short, small strokes following the contours of the face. Avoid areas of sharp detail like eyelashes, eyebrows, and the edges of lips. The goal is to create smoother transitions in the tones.
* Blur Tool: Can be used for subtle smoothing, but be careful not to over-blur and lose detail. Set the Strength to a low value (5-10%).
* Healing Brush Tool / Spot Healing Brush Tool: Can be used for larger blemishes, but be careful not to introduce new textures into the low-frequency layer.
* Zoom In: Work at 100% zoom to accurately see the effect of your retouching.
* Work Gradually: It's better to make small adjustments rather than drastic changes.
5. Retouching the High Frequency Layer:
* Select the "High Frequency" layer.
* Tools to use: Choose one of the following tools:
* Clone Stamp Tool: This is the primary tool for removing blemishes and unwanted texture.
* Select the Clone Stamp Tool (looks like a rubber stamp).
* In the options bar at the top, set the following:
* Mode: "Normal"
* Opacity: Start with 10-20% for subtle blending. Increase as needed.
* Flow: Start with 10-20%
* Aligned: Usually Checked.
* Sample: "Current Layer"
* Zoom In: Work at 100% or higher.
* Sampling: Hold `Alt` (Windows) or `Option` (Mac) and click on a clean area of skin *near* the blemish to sample that texture.
* Painting: Click or paint over the blemish. The goal is to replace the unwanted texture with the clean texture you sampled. Use very short strokes. Sample new areas frequently to avoid repeating the same texture.
* Important: Try to sample texture from an area that is similar in lighting and tone to the area you're correcting. If the lighting is different, the cloned texture will look out of place.
* Patch Tool: Can be used for larger areas, but it can sometimes create noticeable seams.
6. Refine and Adjust:
* Check at Different Zoom Levels: Zoom in and out to check your work at different magnifications.
* Use Layer Masks: If you need to undo a specific area, create a layer mask on the "Low Frequency" or "High Frequency" layer and paint with black to hide the effect in that area, or white to reveal it.
* Adjust Opacity: If the overall effect is too strong, reduce the opacity of either the "Low Frequency" or "High Frequency" layer.
* Consider the Lighting: Be mindful of how your retouching affects the lighting and shadows on the face.
Tips and Considerations:
* Non-Destructive Workflow: Frequency separation is a non-destructive technique because you're working on duplicate layers. The original image remains untouched.
* Subtlety is Key: The best retouching is often unnoticeable. Don't over-smooth the skin to the point where it looks fake or plastic.
* Preserve Texture: The goal is to improve the skin's appearance while maintaining a natural look. Avoid removing *all* the texture.
* Practice: Frequency separation takes practice to master. Experiment with different settings and techniques to find what works best for you and your style.
* Higher Resolution Images: Frequency separation works best on high-resolution images because you have more detail to work with.
* Consider Shadows and Highlights: Pay close attention to how the lighting is affected by your retouching. You may need to adjust the shadows and highlights to maintain a natural look.
* Don't Overdo It: It's easy to get carried away with retouching. Step back and look at the image as a whole to make sure you're not overdoing it. Less is often more!
* Grouping the Layers: Select the low and high frequency layers and press Ctrl + G (or Cmd+G on Mac) to put them in a group. You can turn the entire retouching process on and off and adjust the group layer's opacity.
Example Workflow Summary:
1. Duplicate Background Layer twice.
2. Name layers "High Frequency" and "Low Frequency".
3. Hide "High Frequency" layer.
4. Select "Low Frequency" layer and apply Gaussian Blur (adjust radius until skin imperfections are softened, typically 2-4px).
5. Unhide "High Frequency" layer.
6. Select "High Frequency" layer and go to Image > Apply Image.
7. Apply Image settings: Layer = "Low Frequency", Blending = "Subtract", Scale = 2, Offset = 128, Channel = RGB.
8. Change "High Frequency" layer blending mode to "Linear Light".
9. Select "Low Frequency" layer and use Mixer Brush Tool or Blur Tool to smooth skin tones.
10. Select "High Frequency" layer and use Clone Stamp Tool to remove blemishes.
11. Refine, adjust, and use layer masks as needed.
By following these steps and practicing, you can use frequency separation to achieve professional-looking portrait retouching results in Photoshop. Good luck!