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 left-hand toolbar, find the Lasso Tool. It might be hidden under the regular Lasso Tool or the Polygonal Lasso Tool.
* Click and *hold* on the Lasso Tool icon to reveal the fly-out menu.
* Select the Magnetic Lasso Tool (the icon looks like a lasso with a magnet on it).
3. Adjust the Magnetic Lasso Tool Settings:
* Look at the options bar at the top of the screen. Adjust the settings to suit your image. Here's a breakdown:
* Width: This determines the area the tool searches for an edge. A lower width (e.g., 5-10 pixels) is better for sharp, well-defined edges. A higher width (e.g., 20-40 pixels) might be necessary for softer edges or more complex backgrounds. Experiment to see what works best.
* Contrast: This determines how much contrast is needed for the tool to detect an edge. Higher contrast means it needs a more defined edge. Lower contrast is better for softer transitions. Start around 10-20% and adjust as needed.
* Frequency: This sets the frequency at which the tool places anchor points. Higher frequency means more anchor points, resulting in a more precise selection but potentially a more jagged edge. Lower frequency means fewer anchor points, resulting in a smoother selection but potentially less accuracy. Start around 50-60 and adjust.
* Pen Pressure: If you're using a graphics tablet, you can enable this to control the width with pen pressure.
4. Start Making the Selection:
* Click once on the edge of your subject to create the first anchor point.
* Carefully move the cursor along the edge of the subject. The Magnetic Lasso Tool will automatically snap to what it perceives as the edge based on the settings you've configured.
* As you move, Photoshop will place anchor points. Don't worry if it's not perfect; you can adjust them later.
* For tricky areas (e.g., hair), move slower and adjust the tool settings if necessary.
* Correcting Mistakes:
* If the tool places an anchor point in the wrong place, press the Delete key (or Backspace on Windows) to remove the last anchor point and reposition the cursor.
* If the tool is getting completely lost, try clicking manually to place an anchor point where you want it, then resume letting the tool do its thing.
5. Complete the Selection:
* Once you've traced all the way around your subject, bring the cursor back to the starting anchor point.
* A small circle will appear next to the cursor when you're over the starting point. Click to close the selection. You should now see the "marching ants" indicating the selection.
6. Refine the Selection (Very Important!)
* The Magnetic Lasso Tool is good, but rarely perfect. Use the Refine Edge (or Select and Mask in newer versions) feature to improve the selection, especially around hair.
* Go to `Select > Select and Mask` (or `Select > Refine Edge` in older versions).
* In the Select and Mask workspace:
* View Mode: Choose a view mode that helps you see the selection clearly (e.g., "Overlay").
* Edge Detection:
* Radius: Increase the radius slightly to help detect edges around hair. Start with a small value (e.g., 1-2 pixels) and increase gradually.
* Smart Radius: Check this box. It allows the radius to vary along the selection edge, providing better results.
* Global Refinements: These are powerful tools to refine the edge:
* Smooth: Smooths out jagged edges. Use sparingly.
* Feather: Blurs the edge slightly, which can help blend the subject into the background after blurring. Use a very small value (e.g., 0.5-1 pixel).
* Contrast: Increases the contrast of the edge. Use sparingly.
* Shift Edge: Moves the edge inward or outward. Use this to compensate for errors in the initial selection. A negative value moves the edge inward (useful for removing halos).
* Decontaminate Colors: This is particularly important for hair. It removes color fringing (color cast from the background) around the edges of the selection. Check the box and adjust the Amount slider until the fringing is gone.
* Output Settings:
* Output To: Choose `New Layer with Layer Mask`. This is the recommended option because it creates a non-destructive mask, allowing you to easily adjust the selection later if needed.
* Click "OK" to apply the refined selection. You should now have a new layer with a layer mask.
7. Invert the Selection:
* With the new layer selected (the one with the layer mask), go to `Select > Inverse`. This will select the *background* instead of the subject.
8. Apply the Blur:
* Go to `Filter > Blur > Gaussian Blur`.
* A dialog box will appear. Adjust the Radius slider to control the amount of blur. A higher radius will create a more pronounced blur.
* Preview the blur in the image window and find a level that looks natural and pleasing.
* Click "OK".
9. Adjust the Blur (Optional):
* If you want to adjust the blur later, double-click on the "Gaussian Blur" filter listed under the layer in the Layers panel. This will reopen the Gaussian Blur dialog, allowing you to change the radius.
10. Optional: Add a Color Grade or Adjustment Layer:
* This step is optional. To make the blur more natural and blend with the subject, create a new layer above all others. Set the blend mode to "Soft Light" or "Overlay" and gently paint in some colors from the surrounding environment.
11. Save Your Image:
* Go to `File > Save As`.
* Choose a file format (JPEG for general use, PNG for transparency, TIFF for high-quality archiving).
* Name your file and click "Save".
Tips for Success:
* Zoom In: When making the selection, zoom in to get a more accurate result.
* Take Your Time: Don't rush the selection process. The more careful you are, the better the final result will be.
* Experiment with Settings: Don't be afraid to experiment with the Magnetic Lasso Tool settings (width, contrast, frequency) and the Gaussian Blur radius.
* Refine Edge is Key: Spend time in the Select and Mask workspace. It's crucial for achieving a professional-looking result, especially around hair.
* Consider the Context: The amount of blur you apply should be appropriate for the subject and the scene. Too much blur can look unnatural.
* Non-Destructive Editing: Using a layer mask is a non-destructive approach. You can always adjust the mask or the blur later without affecting the original image.
* Alternative Tools: For extremely complex selections (e.g., very fine hair), consider using more advanced tools like the Pen Tool or the Channel Masking technique.
Troubleshooting:
* Jagged Edges: Increase the "Smooth" setting in the Refine Edge/Select and Mask workspace. Also, make sure the Frequency setting of the Magnetic Lasso wasn't too high when you initially made the selection.
* Halo Effect: If you see a bright outline around the subject, decrease the "Shift Edge" setting in the Refine Edge/Select and Mask workspace (move it towards the negative side). Also, make sure the "Decontaminate Colors" option is enabled.
* Selection Not Accurate: Adjust the "Width," "Contrast," and "Frequency" settings of the Magnetic Lasso Tool and try again. You might need to manually click more often in difficult areas.
By following these steps, you should be able to effectively blur the background of your portrait using the Magnetic Lasso Tool and create a pleasing depth-of-field effect. Remember to practice and experiment to get the best results for your specific images. Good luck!