Steps:
1. Open your image in Photoshop.
2. Duplicate the Layer (Important!). Go to Layer > New > Layer via Copy (or press Ctrl+J / Cmd+J). This creates a duplicate layer (Layer 1) above your original background layer. This is crucial so you can blur the background without permanently altering the original image.
3. Select the Magnetic Lasso Tool: Find the Magnetic Lasso Tool in the toolbar (it's usually nested under the Lasso Tool). If you see a different Lasso tool, click and hold the Lasso icon until a flyout menu appears, then select the Magnetic Lasso Tool.
4. Configure the Magnetic Lasso Tool (Important): In the Options Bar (the bar at the top of the screen), adjust the following settings:
* Width: This determines how far away from the edge the tool will "snap." Start with a smaller number (around 5-10 pixels) and adjust as needed. A higher number will make it more aggressive in snapping.
* Contrast: This controls the sensitivity to contrast. A higher contrast value will help it stick to edges with strong contrast. Start around 10-20% and adjust.
* Frequency: This sets how often the tool places anchor points along the edge. A higher frequency creates more anchor points and potentially a more precise selection but also more to edit. Start around 50-60.
* Stylus Pressure: Leave this unchecked unless you're using a graphics tablet with pressure sensitivity.
5. Trace the Subject:
* Click once at the starting point along the edge of your subject. This sets your first anchor point.
* Slowly move the Magnetic Lasso Tool along the edge of the subject. Photoshop will automatically try to snap the selection to the edge.
* If the tool snaps to the wrong spot, press the Delete (or Backspace) key to remove the last anchor point, then move the tool back and try again.
* For curved areas, move more slowly.
* To force the tool to place an anchor point, click manually. This is useful for areas with low contrast or where the tool is struggling.
* When you reach the starting point, hover over the original starting point anchor and you should see a small circle appear next to your cursor. Click to close the selection.
6. Refine the Selection (Important!): The Magnetic Lasso Tool rarely creates a perfect selection. You'll need to refine it.
* Select and Mask Workspace: Go to `Select > Select and Mask`. This opens a dedicated workspace for refining selections.
* Choose a View Mode: In the `Select and Mask` workspace, choose a view mode that helps you see the selection clearly (e.g., Overlay, On Black, On White).
* Refine Edge Brush Tool (Crucial for Hair!): Select the `Refine Edge Brush Tool` (looks like a brush with a plus sign). Carefully paint along the edges of the subject, especially around hair, fur, or other fuzzy areas. This tool intelligently identifies and refines the selection, helping to include stray hairs. Make small strokes and don't overdo it. Experiment with the `Radius` setting to control the area the tool affects.
* Brush Tool (For Manual Corrections): Use the regular Brush Tool (press `B`) with a hard or soft edge (adjust in the Options Bar). Set the Mode to `Add` or `Subtract` to manually add or remove areas from the selection. Use the `Size` and `Hardness` settings to adjust the brush as needed. Zoom in close to make accurate corrections.
* Global Refinements: In the Properties panel on the right, adjust these settings:
* Smooth: Smooths out jagged edges.
* Feather: Blurs the edge of the selection to help it blend with the background. Start with a very small value (e.g., 0.5 - 1 pixel) and increase if needed. Too much feathering will make the edge look blurry.
* Contrast: Sharpens the edge of the selection. Use sparingly.
* Shift Edge: Shifts the selection boundary inward (negative value) or outward (positive value). Useful for tightening or loosening the selection.
* Decontaminate Colors: Helps remove color fringing along the edge of the selection. Sometimes this can introduce unwanted colors, so use with caution.
* Output To: In the `Output Settings` section at the bottom, make sure the "Output To" option is set to `Selection` or `Layer Mask` and click `OK`. If you output to "Selection," it will create a selection based on your refinements. If you output to "Layer Mask," it will create a layer mask. Choose based on personal preference. Creating a layer mask is generally safer as it's non-destructive.
7. Invert the Selection: If you output a selection, you need to invert it to select the background. Go to `Select > Inverse` (or press Ctrl+Shift+I / Cmd+Shift+I).
8. Apply Blur: With the background selected (or the layer mask active with the subject hidden), go to `Filter > Blur > Gaussian Blur`.
* Adjust the Radius to control the amount of blur. Experiment until you achieve the desired effect. A higher radius creates a more intense blur.
* Click `OK`.
9. Fine-tune (Optional):
* Adjust Blur Amount: If the blur is too strong or too weak, you can reapply the Gaussian Blur with a different radius, or use `Edit > Fade Gaussian Blur` immediately after applying the blur to reduce its intensity.
* Layer Masks (Recommended for Non-Destructive Editing): If you chose to output a Layer Mask in Step 6:
* The mask is white where the layer is visible, black where it's hidden.
* To edit the mask, select it (click on the mask thumbnail).
* Use a brush tool with black to hide parts of the layer (blur).
* Use a brush tool with white to reveal parts of the layer (remove blur).
* Use gray to partially hide/reveal. The darker the gray, the more hidden it is.
Alternative and Better Methods (Recommended):
* Quick Selection Tool/Object Selection Tool: These tools are generally faster and more intuitive than the Magnetic Lasso for making initial selections. They work by identifying objects and edges, and allow you to quickly select the subject. You can then refine the selection in the "Select and Mask" workspace as described above.
* Select Subject: (Select > Subject) Photoshop's AI-powered subject selection tool is incredibly powerful and often produces excellent results with minimal effort. After using this, always refine with the "Select and Mask" workspace.
* Pen Tool: For the most precise control, use the Pen Tool to create a path around the subject. This takes more time but allows for the highest level of accuracy. Convert the path to a selection (right-click on the path and choose "Make Selection") and refine in the "Select and Mask" workspace.
Tips and Considerations:
* Zoom In: Zoom in close (200-400%) to make precise selections, especially around complex areas like hair and clothing.
* Start with a Good Image: A photo with good contrast between the subject and background will make the selection process easier.
* Use a Wacom Tablet (If Available): A graphics tablet gives you more precise control when using the selection tools, especially the Refine Edge Brush Tool.
* Non-Destructive Editing: Always work on a duplicate layer and use layer masks. This allows you to adjust the blur or refine the selection later without permanently altering the original image.
* Experiment: The best settings for the Magnetic Lasso Tool will vary depending on the image. Experiment with different width, contrast, and frequency values to find what works best.
* Hair and Fine Details: Hair is notoriously difficult to select. The Refine Edge Brush Tool is essential for achieving realistic results.
* Avoid Over-Blurring: A subtle blur is often more effective than an extreme blur. An overly blurred background can look artificial.
* Use Depth of Field as a Guide: Observe how the background blurs in real-life photos with shallow depth of field and try to replicate that effect in Photoshop.
In summary, while the Magnetic Lasso Tool can be used to blur the background, it's not the ideal choice for complex selections. The Quick Selection Tool, Select Subject, or Pen Tool, combined with the Select and Mask workspace, are generally more efficient and provide better results. Remember to work non-destructively by using duplicate layers and layer masks, and to refine your selection carefully for a realistic and professional-looking result.