Steps for Blurring the Background with the Magnetic Lasso Tool:
1. Open Your Image: Open the portrait image in Photoshop.
2. Select the Magnetic Lasso Tool: Find the Lasso Tool in the toolbar (it looks like a lasso). Click and hold on the Lasso Tool icon. A flyout menu will appear. Choose the Magnetic Lasso Tool.
3. Adjust Tool Settings (Important): In the Options Bar at the top of the screen, adjust the following settings:
* Width: This setting determines how far the Magnetic Lasso Tool looks for edges. Start with a value like 10px and adjust as needed. Higher values are useful for images with high contrast edges, while lower values work better for softer edges.
* Contrast: This setting influences how sensitive the tool is to changes in contrast. A higher percentage (e.g., 80%) will make it more sensitive to contrast, snapping to edges more aggressively. A lower percentage (e.g., 10%) will be less sensitive.
* Frequency: This setting determines how often the tool places anchor points. Higher frequencies create more precise selections but can also lead to more points to correct later. Start with a value around 57 and adjust according to the image complexity.
* Edge Detection (Wacom Tablet users): If you are using a Wacom tablet, you will have pen pressure sensitivity options, this can give you better control over the tool.
4. Start Tracing the Subject:
* Click near the edge of the subject you want to isolate. This will create the first anchor point.
* Carefully move your mouse along the edge of the subject. The Magnetic Lasso Tool will automatically try to snap to the edge.
* If the tool makes a mistake and snaps to the wrong area, you can:
* Delete the last anchor point: Press the Delete or Backspace key.
* Manually add an anchor point: Click to manually place an anchor point in a specific spot where you want the selection to be. This is useful for challenging areas.
* Continue tracing the entire outline of the subject.
5. Close the Selection:
* When you reach the starting point, a small circle will appear next to the cursor.
* Click to close the selection. The selected area will now be surrounded by a "marching ants" outline.
6. Refine the Selection (Crucial Step): This is where the Magnetic Lasso Tool often falls short, especially with hair and soft edges.
* Go to Select > Select and Mask. This opens the Select and Mask workspace.
* View Mode: Choose a view mode that helps you see the selection clearly (e.g., "On Layers" or "Overlay").
* Global Refinements:
* Opacity: Adjust the opacity of the view so you can see the edge of the subject and the background.
* Edge Detection:
* Radius: Increase the Radius slightly to help Photoshop find edges. Start with a low value (e.g., 1-2 pixels) and increase it gradually. Too high a radius can blur the selection.
* Smart Radius: Turn on Smart Radius to vary the radius of the edge detection according to the complexity of the edges.
* Global Adjustments:
* Smooth: Slightly increase the Smoothness to reduce jagged edges.
* Feather: Add a small amount of Feather to soften the selection edge (usually 0.5 - 1 pixel).
* Contrast: Increase the Contrast to sharpen the selection edge. Be careful not to add too much, as this can create hard edges.
* Shift Edge: Slightly adjust the Shift Edge slider. Moving it to the left will shrink the selection, while moving it to the right will expand it. This is useful for removing halos or fringes.
* Refine Edge Brush Tool:
* Select the Refine Edge Brush Tool (it looks like a brush with a plus sign). This tool is essential for refining the selection, especially around hair and other fine details.
* Paint over the edges of the hair and other problematic areas. The tool will attempt to refine the selection, removing the background color and preserving the detail of the subject.
* Use the Erase Brush Tool (Hold down the ALT/Option key when the Refine Edge Brush Tool is selected) to erase portions of the refined edge if needed.
7. Output Settings in Select and Mask:
* Output To: Choose "New Layer with Layer Mask". This creates a new layer containing your subject, with a layer mask that hides the background. This is a non-destructive way to work, so you can always edit the mask later.
8. Blur the Background:
* Select the original layer (the one with the full image).
* Go to Filter > Blur > Gaussian Blur.
* Adjust the Radius slider to control the amount of blur. A higher radius will create a more dramatic blur. Experiment to find the look you want. Usually, a value between 5 and 20 pixels is a good starting point.
* Click OK.
Alternative Blurring Methods (Recommended):
* Use a Lens Blur (Filter > Blur Gallery > Iris Blur or Field Blur): These filters simulate the effects of a camera lens, creating a more realistic and gradual blur. Iris Blur is especially useful for mimicking the effect of a shallow depth of field.
* Content-Aware Fill (for removing small distractions): If the background is simple, you can use Content-Aware Fill to remove distracting elements before blurring.
Why the Magnetic Lasso Tool Isn't Ideal:
* Hair: The Magnetic Lasso Tool struggles with hair and fine details. The Refine Edge Brush in the Select and Mask workspace is essential for correcting this, but it's still more difficult than using other selection methods.
* Soft Edges: The tool can have difficulty accurately detecting soft edges, especially in low-contrast areas.
* Complexity: More complex backgrounds can confuse the tool, leading to inaccurate selections.
* Speed: While the Magnetic Lasso Tool seems fast, the necessary corrections in Select and Mask can often make it slower than other methods.
Better Alternatives:
* Quick Selection Tool: Often faster and more intuitive for initial selections, especially on subjects with clearly defined edges.
* Select Subject (Select > Subject): Photoshop's AI-powered tool that automatically detects the subject in the image. It's often a good starting point, even if you need to refine the selection afterward.
* Pen Tool: The most precise tool for creating selections, but it requires more practice. It's ideal for complex shapes and situations where accuracy is paramount.
* Channels: In some cases, using color channels to create a mask is very effective, especially when there's a strong color difference between the subject and the background.
Tips and Considerations:
* Zoom In: Zoom in on the image to make more accurate selections, especially when using the Magnetic Lasso Tool.
* Work Non-Destructively: Always use layer masks to hide unwanted areas instead of deleting them. This allows you to easily edit the selection later.
* Experiment with Settings: Adjust the Magnetic Lasso Tool settings to find the best combination for your specific image.
* Practice: Practice with different images and tools to improve your selection skills.
In summary: While you *can* use the Magnetic Lasso Tool to blur the background of a portrait, it's usually not the best choice. Start with "Select Subject" or the Quick Selection Tool and then go to Select and Mask to refine the selection, using the Refine Edge Brush Tool for hair. Using the magnetic lasso tool alone will likely require significant touch-up and may not produce the best results. Then blur the background using Gaussian Blur or a Lens Blur filter.