Key Idea: You'll select the subject, invert the selection to select the background, and then apply a blur filter to the background.
Steps:
1. Open Your Image in Photoshop:
* Launch Photoshop.
* Go to `File > Open...` and select the portrait 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 fly-out menu will appear.
* Choose the Magnetic Lasso Tool.
3. Adjust the Magnetic Lasso Tool Settings (Important!):
* In the options bar at the top of the screen (just below the menu bar), you'll see settings for the Magnetic Lasso Tool. Adjust these settings *before* you start tracing:
* Width: This determines how far the tool looks for edges. A larger value (e.g., 10-20 px) is good for distinct edges. A smaller value (e.g., 4-8 px) is better for more detailed or complex edges, like hair. Start with a mid-range value and adjust as you go.
* Contrast: This dictates how sensitive the tool is to differences in contrast. A higher value (e.g., 15-20%) will stick to edges with strong contrast. A lower value (e.g., 5-10%) is better for softer edges.
* Frequency: This controls how often the tool places "fastening points" (the little squares you see). A higher frequency will create a more detailed selection, but can also make it more difficult to control. A lower frequency is smoother, but might miss details. A value of 50-60 is a good starting point.
* Important Tip: Don't be afraid to experiment with these settings. You can always undo your selection and try again with different settings.
4. Trace the Subject's Outline:
* Start Point: Click once anywhere on the edge of your subject to set the starting point for your selection.
* Tracing: Move your mouse along the edge of your subject. The Magnetic Lasso Tool will automatically try to "snap" to the edge, creating fastening points as you go.
* Let the Tool Do Its Job: The key is to move the mouse slowly and steadily along the edge, letting the tool find the edge for you.
* Correcting Mistakes:
* If the tool makes a mistake and snaps to the wrong place, press the Delete key (or Backspace on Windows) to remove the last fastening point. Then reposition your mouse and continue tracing.
* If you need to zoom in for greater accuracy, use the Zoom tool (magnifying glass icon) or the keyboard shortcut Ctrl + '+' (Cmd + '+' on Mac). Hold down the spacebar to temporarily activate the Hand tool for panning.
* Closing the Selection: When you reach the starting point, move your mouse over the starting point. A small circle will appear next to the cursor. Click to close the selection.
5. Refine the Selection (Important!):
* Select and Mask (Refine Edge): After you close the selection, go to `Select > Select and Mask...` (In older versions of Photoshop, this might be called `Refine Edge...`). This is *crucial* for cleaning up the selection, especially around hair or other fine details.
* Select and Mask Settings: In the Select and Mask workspace, you'll find several settings:
* View: Choose a view mode that helps you see the selection clearly. "Overlay" is a popular choice (highlights the unselected area in red).
* Edge Detection:
* Radius: Increase the radius slightly (e.g., 1-3 pixels) to have Photoshop look around the edge for the best possible definition. Don't overdo it, or you'll lose detail.
* Smart Radius: This is usually helpful; leave it checked.
* Global Refinements:
* Smooth: Slightly increases the smoothness of the selection boundary. Use with caution; too much can blur the details.
* Feather: Softens the selection edge. A very small amount (e.g., 0.2-0.5 pixels) can help blend the subject into the background more naturally. Again, don't overdo it.
* Contrast: Increases the contrast along the selection edge, making it sharper.
* Shift Edge: This is useful if your selection is slightly too large or too small. Negative values shrink the selection; positive values expand it.
* Refine Edge Brush Tool (Important): This is the most important tool in this workspace. Select the Refine Edge Brush Tool (it's in the toolbar on the left side of the workspace).
* Brush over edges: Use the Refine Edge Brush Tool to paint over the edges of the subject, especially around hair, fur, or other fine details. Photoshop will analyze the area you're painting and try to improve the selection. Use a smaller brush size for fine details.
* Output Settings:
* Output To: Choose "Selection" or "New Layer with Layer Mask". "New Layer with Layer Mask" is generally recommended. This will create a new layer with a mask, allowing you to make adjustments later without affecting the original image.
* Click OK to exit the Select and Mask workspace.
6. Invert the Selection:
* Go to `Select > Inverse` (or press Ctrl + Shift + I / Cmd + Shift + I). This will select everything *except* your subject – i.e., the background.
7. Apply a Blur Filter:
* Go to `Filter > Blur > Gaussian Blur...` (Gaussian Blur is a common and effective choice).
* Adjust the Radius: In the Gaussian Blur dialog box, adjust the Radius slider. This controls the amount of blur. A small radius will create a subtle blur, while a larger radius will create a more dramatic blur. The appropriate value depends on the image and the desired effect. Experiment until you're happy with the result. A radius of 3-10 pixels is often a good starting point.
* Click OK.
8. Optional: Adjust the Blur Further (if needed):
* If you want to change the amount of blur after applying the filter, you can:
* Undo the blur (Ctrl+Z / Cmd+Z) and reapply it with a different radius.
* Use a layer mask on the blurred layer and paint with black or white to selectively reveal or hide the blur in certain areas. This gives you more control over the final result.
9. Save Your Work:
* Go to `File > Save As...`
* Choose a file format that preserves layers (e.g., PSD or TIFF) if you want to be able to edit the image later.
* Alternatively, save as a JPEG if you're finished and just need a web-friendly image.
Tips and Tricks:
* Zoom In: Zoom in to 200% or more when tracing tricky areas like hair or complex edges.
* Use Short Strokes: With the Magnetic Lasso Tool, sometimes it's better to use short, deliberate mouse movements rather than long, sweeping strokes.
* Feather the Selection: If the blurred background looks unnatural, try adding a small amount of feathering to the original selection (before inverting and blurring). This will soften the edges of the subject and help it blend into the blurred background more seamlessly. You can do this in the Select and Mask workspace.
* Layer Masks: Consider placing your subject on a separate layer with a layer mask *before* you blur the background. This allows you to easily refine the selection and make adjustments to the blur later without affecting the original image.
* Other Blur Filters: Experiment with other blur filters like *Lens Blur* or *Field Blur* for more realistic depth-of-field effects. Lens Blur can be particularly effective, but it can be more processor-intensive.
When to Use the Magnetic Lasso Tool (and when not to):
* Good For: Images with clear contrast between the subject and the background. It's particularly useful for subjects with fairly well-defined edges.
* Not Ideal For: Images with very complex edges (e.g., wispy hair against a busy background), or when the subject and background have similar colors and contrast. In these cases, you might want to try a more advanced selection technique, such as using channels, Pen Tool, or one of Photoshop's object selection tools.
By following these steps and tips, you can effectively blur the background of your portrait and create a more professional-looking image. Remember to practice and experiment with different settings to find what works best for each image. Good luck!