Overview
The general process is:
1. Select the Subject: Use the Magnetic Lasso Tool to create a precise selection around the person in the portrait.
2. Invert the Selection: Select the background instead of the subject.
3. Apply Blur: Use a blur filter to soften the background.
Step-by-Step Guide
1. Open Your Image in Photoshop
* Go to `File > Open` and choose the portrait image you want to edit.
2. Select the Magnetic Lasso Tool
* In the Tools panel (usually on the left side of your screen), find the Lasso Tool icon. It looks like a lasso.
* Click and hold on the Lasso Tool icon. A flyout menu will appear.
* Select the Magnetic Lasso Tool. It's the one with a little magnet attached to the lasso.
3. Adjust Magnetic Lasso Tool Settings (Important!)
* At the top of the screen, look at the Options Bar for the Magnetic Lasso Tool:
* Width: This controls how far the tool will "look" for edges. A higher value allows it to snap to edges that are further away, but it can also be less accurate. Start with a value around 5-10 pixels and adjust as needed. For high-resolution images, you might need a larger width.
* Contrast: This determines how sensitive the tool is to changes in contrast. Higher contrast values will cause it to stick to edges with strong contrast. Lower values allow it to find edges with subtler contrast. Start with a value of 10-20% and adjust.
* Frequency: This controls how often the tool places "fastening points" (little anchors that define your selection). Higher frequencies result in a more detailed selection but can also create more points that need adjusting. Start around 5-10 and adjust.
* Pen Pressure: This enables or disables using a pressure-sensitive tablet to control the width of the selection. If you're using a mouse, leave this unchecked.
* Modes: Choose the appropriate mode:
* New Selection: Creates a brand new selection.
* Add to Selection: Lets you add to an existing selection (useful for correcting mistakes).
* Subtract from Selection: Lets you remove from an existing selection.
* Intersect with Selection: Only keeps the area where a new selection overlaps an existing one.
4. Create the Selection
* Start Clicking: Click once at an obvious starting point on the edge of your subject. This creates the first anchor point.
* Trace the Edge: Slowly move your mouse (or stylus) along the edge of the subject. The Magnetic Lasso Tool will try to "snap" to the edge.
* Click Periodically: If the edge is very defined, you may not need to click much. But in areas where the edge is blurry or complex, click more frequently to create more anchor points and guide the tool.
* Correcting Mistakes:
* Backspace/Delete: If the tool makes a mistake, press the Backspace (Windows) or Delete (Mac) key to remove the last anchor point. Then, move your mouse back to where you made the error and try again.
* Add/Subtract (using Modes): If the tool misses part of the subject or selects part of the background, you can use the "Add to Selection" and "Subtract from Selection" modes (mentioned in Step 3) to refine your selection.
* Close the Selection: When you reach the starting point, move your mouse cursor over the first anchor point you created. A small circle will appear next to the cursor. Click to close the selection. Alternatively, you can simply double-click to automatically close the selection.
5. Refine the Selection (Very Important!)
* Select and Mask: Go to `Select > Select and Mask...` This opens a dedicated workspace for refining selections. This is where you can dramatically improve the quality of your selection, especially around hair and edges.
* In the Select and Mask workspace:
* View Mode: Choose a view mode that helps you see the selection clearly (e.g., Overlay, On Black, On White).
* Edge Detection:
* Radius: Increase the Radius slider slightly to allow the tool to look for edges further away from the initial selection.
* Smart Radius: Enable Smart Radius to allow the radius to vary along the edge.
* Global Refinements:
* Smooth: Slightly increase the Smooth slider to reduce jaggedness in the selection.
* Feather: Add a small amount of Feather (0.5-1 pixel) to soften the edge of the selection and help it blend better with the blurred background. Too much feathering will make the subject look blurry.
* Contrast: Increase the Contrast slider slightly to sharpen the edge of the selection.
* Shift Edge: Slightly adjust the Shift Edge slider. Moving it to the left contracts the selection (useful if you selected too much background). Moving it to the right expands the selection (useful if you selected too little of the subject).
* Refine Edge Brush Tool: This is your best friend!
* Select the Refine Edge Brush Tool (it's in the toolbar on the left of the Select and Mask workspace, looks like a brush with hair).
* Paint along the edges of the subject, especially around hair, fur, or other difficult areas. The Refine Edge Brush Tool will intelligently analyze the edge and improve the selection.
* Output Settings:
* Output To: Change the "Output To" setting to `New Layer with Layer Mask`. This is the best option because it creates a non-destructive mask, allowing you to easily adjust the selection later.
* Click OK: Exit the Select and Mask workspace. You'll have a new layer with a layer mask.
6. Invert the Selection
* Select the layer mask: In the Layers panel, click on the thumbnail of the layer mask (the black and white rectangle) that was created. This ensures that you're working on the mask, not the image itself.
* Invert the mask: Press `Ctrl+I` (Windows) or `Cmd+I` (Mac) to invert the mask. This will select the *background* instead of the subject. The layer mask thumbnail will now be the opposite of what it was. If you had a white subject on a black background in the layer mask, you will now have a black subject on a white background in the layer mask.
7. Apply the Blur
* Select the image layer: In the Layers panel, click on the thumbnail of the actual image layer (the one with the portrait). *Do not* select the layer mask thumbnail. You want to blur the image itself, not the mask.
* Apply Blur Filter: Go to `Filter > Blur > Gaussian Blur...`
* Adjust Radius: In the Gaussian Blur dialog box, adjust the "Radius" slider to control the amount of blur. A lower radius will create a subtle blur, while a higher radius will create a more dramatic blur. Watch the preview window to see the effect. The amount of blur you need depends on the image and your desired effect. Start with a small value like 2-3 pixels and increase as needed.
* Click OK.
8. Fine-Tune (Optional)
* Adjust Blur Amount: If you want to change the amount of blur later, you can double-click on "Gaussian Blur" under the layer in the Layers panel. This will re-open the Gaussian Blur dialog box, allowing you to adjust the Radius.
* Adjust Mask: If the selection isn't perfect, you can edit the layer mask to refine the edges.
* Select the layer mask: Click on the layer mask thumbnail.
* Use the Brush Tool (B):
* Black: Painting with black on the layer mask *hides* parts of the layer (revealing the layers below, if any). This is used to subtract from the selection (remove background that was incorrectly selected).
* White: Painting with white on the layer mask *reveals* parts of the layer. This is used to add to the selection (include parts of the subject that were incorrectly hidden).
* Gray: Painting with gray on the layer mask creates partial transparency. This is useful for softening the edge of the selection.
* Adjust Brush Settings: In the Options Bar at the top, adjust the Brush Size, Hardness (soft edges blend better), and Opacity (lower opacity for subtle adjustments).
Tips for Better Results
* High-Resolution Images: For high-resolution images, use a higher Width setting for the Magnetic Lasso Tool and a larger Radius for the Gaussian Blur.
* Complex Edges (Hair, Fur): Use the Refine Edge Brush Tool in Select and Mask extensively. It's critical for getting realistic results around complex edges.
* Non-Destructive Editing: Always use a layer mask. This allows you to edit the selection later without permanently altering the original image.
* Experiment: Don't be afraid to experiment with the Magnetic Lasso Tool settings and the Gaussian Blur Radius to find what works best for your image.
* Practice: The more you use the Magnetic Lasso Tool, the better you'll become at creating accurate selections.
* Consider Content-Aware Fill: If the background is relatively simple, you might be able to remove it completely and use Content-Aware Fill (`Edit > Fill > Content-Aware`) to fill in the empty space. Then you wouldn't even need to blur it. This works best when the area to be filled is small and has a consistent texture.
* Use Other Selection Tools: For some images, other selection tools like the Quick Selection Tool or the Pen Tool might be more appropriate than the Magnetic Lasso Tool. Choose the tool that works best for the specific image and the complexity of the edges.
* Don't Over-Blur: A too-blurred background can look unnatural and draw attention to the effect itself. Aim for a subtle blur that separates the subject from the background without making it look fake.
* Consider Lens Blur (Depth of Field): For a more realistic blur, explore the `Filter > Blur > Lens Blur` filter. This allows you to simulate the depth of field effect of a camera lens, providing more control over the blur's shape and intensity. However, it is more complex than Gaussian blur and may require creating a depth map.
* Be Patient: Creating a good selection takes time and attention to detail. Don't rush the process.
By following these steps and tips, you can effectively blur the background of your portraits in Photoshop using the Magnetic Lasso Tool and achieve professional-looking results. Good luck!