Overview
The Magnetic Lasso Tool is useful for selecting subjects with reasonably well-defined edges that contrast with the background. It's not always perfect, and you might need to refine your selection.
Steps
1. Open Your Image in Photoshop:
* Go to `File > Open` and select the portrait image you want to edit.
2. Duplicate the Background Layer (Important!):
* This allows you to work non-destructively. If you make mistakes, you can always revert to the original.
* In the Layers panel (usually on the right side of your screen; if not, go to `Window > Layers`), right-click on the "Background" layer and select "Duplicate Layer..."
* Name the new layer something descriptive, like "Portrait" or "Subject," and click "OK."
3. Select the Magnetic Lasso Tool:
* Find the Lasso Tool in the toolbar (it looks like a lasso). Click and hold the Lasso Tool icon. A flyout menu will appear. Select "Magnetic Lasso Tool."
4. Adjust Magnetic Lasso Tool Settings (in the Options Bar at the top):
* Width: This determines how far away from the edge the tool will attempt to "snap" to the contrast. A good starting point is around 10-20 pixels. Adjust it as needed based on the detail of your subject and the contrast with the background. Increase it for more forgiveness, decrease it for finer detail.
* Contrast: This tells the tool how much difference in color it should look for to define an edge. Higher values mean it will only snap to strong contrast edges. Lower values mean it will snap more readily to subtle changes. A good starting point is 10%. Adjust based on your image.
* Frequency: This determines how often Photoshop places anchor points along the selection path. Higher values create more anchor points, resulting in a more accurate selection, but can also make the selection path more rigid. Lower values create fewer anchor points, allowing for smoother curves but potentially less accuracy. A starting point of 57 is good, but adjust accordingly. For complex, detailed edges, a higher frequency is better.
* Feather: Leave this at 0 pixels for now. We'll feather the selection later if needed.
* W (Width), H (Height): These define the size of the magnetic lasso's search area.
5. Start Tracing Your Subject:
* Click once on the edge of your subject to create the starting anchor point.
* Slowly move your cursor along the edge of the subject. The Magnetic Lasso Tool will automatically try to "snap" to the edge.
* When the Lasso Misses: If the lasso starts to stray, you can:
* Click to manually place an anchor point. This forces the lasso to stay on track.
* Press the Delete key (or Backspace on a Mac) to remove the last anchor point and reposition the cursor.
* Around Curves and Tight Spots: Take your time. Short, controlled movements are key. Click to add anchor points more frequently in these areas.
* Completing the Selection: When you reach the starting point, the cursor will change to include a small circle. Click to close the selection. You should now have a "marching ants" outline around your subject.
6. Refine the Selection (Very Important!):
* Select and Mask Workspace: Go to `Select > Select and Mask...` This is a powerful tool for refining selections, especially around hair and other fine details.
* View Mode: Choose a view mode that helps you see the selection clearly (e.g., "Onion Skin," "Overlay," or "On Black").
* Global Refinements:
* Opacity: Adjust to see your selection against the original image.
* Edge Detection - Radius: Increase this slightly to help the tool find softer edges. Start with a small value (e.g., 1-3 pixels) and increase gradually.
* Global Refinements:
* Smooth: Reduces jaggedness along the selection edge. A small amount is usually beneficial.
* Feather: Softens the edges of the selection. This helps blend the subject with the blurred background. A small amount (e.g., 0.5 - 2 pixels) is usually good to start with.
* Contrast: Increases the definition of the edges. Use sparingly, as it can create harsh lines.
* Shift Edge: Moves the selection edge inward or outward. Use this to fine-tune the selection if it's grabbing too much of the background (move inward) or cutting off parts of the subject (move outward).
* Refine Edge Brush Tool (the brush icon on the left toolbar in the Select and Mask workspace): This is your primary tool for refining edges, especially around hair.
* Select the Refine Edge Brush Tool.
* Paint over the edges of your subject, particularly around hair, fur, or other areas where the selection is messy. The tool will attempt to better distinguish between the subject and the background. Use a smaller brush size for finer details.
* Output Settings: At the bottom of the Select and Mask panel, choose "Output To: Layer Mask" from the dropdown menu. This creates a layer mask on your "Portrait" layer.
* Click "OK."
7. Blur the Background:
* Select the "Background" layer (the original, unedited layer).
* Go to `Filter > Blur > Gaussian Blur...`
* Adjust the "Radius" slider until you achieve the desired level of blur. Experiment with different values. A small blur (e.g., 2-5 pixels) is often sufficient. Higher values will create a more dramatic blur. Click "OK."
8. Optional: Adjust the Layer Mask (If Needed):
* If you notice any imperfections in the selection (e.g., halos, hard edges), you can edit the layer mask directly.
* Select the "Portrait" layer.
* Click on the layer mask thumbnail (the black and white rectangle next to the layer thumbnail) to make it the active target.
* Select the Brush Tool (B).
* Set your foreground color to black to hide (erase from the "Portrait" layer) and white to reveal (add back to the "Portrait" layer).
* Paint on the image to refine the mask. Use a soft-edged brush for smoother transitions.
9. Optional: Add a Color Grading:
* Often, blurring can make the background seem tonally disjointed. You may wish to use an adjustment layer (e.g. color balance, selective color, curves) targeted *only* at the background to smooth things out. Alt-click between the adjustment layer and the background layer to clip the adjustment only to that layer.
10. Save Your Work:
* Go to `File > Save As...`
* Choose a file format that supports layers (e.g., PSD or TIFF) if you want to preserve the ability to edit the image later.
* Save a flattened version (e.g., JPEG) for sharing online.
Tips and Best Practices
* Zoom In: Zoom in to at least 100% (or even higher) for precise selections, especially in detail areas.
* Patience is Key: Don't rush the selection process. The more accurate your selection, the better the final result.
* Experiment with Settings: The "Width," "Contrast," and "Frequency" settings of the Magnetic Lasso Tool will vary depending on the image. Experiment to find the best settings for your specific image.
* Consider Other Selection Tools: The Magnetic Lasso Tool isn't always the best choice. For subjects with very complex or poorly defined edges (e.g., hair), consider using the Pen Tool (for precise selections) or the Quick Selection Tool/Select Subject (for automated selections).
* Use a Graphics Tablet (if you have one): A graphics tablet can provide more control and precision when making selections.
* Layer Masks are Your Friend: Always use layer masks. They allow you to non-destructively hide or reveal parts of a layer, giving you flexibility and control.
* Feathering: Adding a slight feather to your selection helps to blend the subject with the blurred background and reduces harsh edges. The *Select and Mask* workspace provides great feathering options.
* Blur Amount: The amount of blur you apply to the background depends on the desired effect. A subtle blur is often more realistic and pleasing than an overly aggressive blur.
* High-Resolution Images: Working with high-resolution images will give you more detail and flexibility when making selections and applying blur effects.
* Practice: The more you practice, the better you'll become at using the Magnetic Lasso Tool and refining selections in Photoshop.
Troubleshooting
* Lasso Snapping to the Wrong Edge: Adjust the "Width" and "Contrast" settings. Try reducing the "Width" to make the tool more sensitive to edges closer to the cursor, and increasing the "Contrast" to make it focus on stronger contrast differences.
* Jagged Edges: Increase the "Smooth" and "Feather" settings in the Select and Mask workspace. Also, use a soft-edged brush to refine the layer mask.
* Halo Effect: The Halo effect around the subject can be reduced by using the *Shift Edge* and *Decontaminate Colors* options in *Select and Mask*. Shift the edge inwards very slightly, and experiment with Decontaminate Colors (output to a new layer *with mask* if you use this)
By following these steps and tips, you can effectively blur the background of portraits using the Magnetic Lasso Tool in Photoshop, creating a professional and visually appealing result. Remember to practice and experiment to find the techniques that work best for you.