Understanding the Process
This method involves carefully selecting the subject of your portrait using the Magnetic Lasso Tool, inverting the selection to target the background, and then applying a blur filter specifically to that background.
Steps:
1. Open Your Image in Photoshop:
* Launch Photoshop and go to `File > Open` and select the portrait you want to edit.
2. Duplicate the Background Layer (Optional but Recommended):
* In the Layers panel (usually located on the right side of the screen), right-click on the "Background" layer.
* Select "Duplicate Layer." This creates a copy of your original image, allowing you to work non-destructively. If you make a mistake, you can simply delete the duplicate. Name the duplicate layer something descriptive, like "Subject Selection."
3. Select the Magnetic Lasso Tool:
* Find the Lasso Tool in the Tools panel (usually on the left side).
* Click and hold on the Lasso Tool icon to reveal a menu.
* Choose the "Magnetic Lasso Tool."
4. Configure the Magnetic Lasso Tool (Important):
* Width: This setting controls how far from your cursor the tool will look for edges. Start with a value between 5-15 pixels. Increase this value if your subject has complex edges or if there's low contrast. Decrease it if you're working with fine details. You can adjust this setting while working.
* Contrast: Determines how much contrast the tool needs to see to define an edge. Start with a value around 10-20%. Increase it if the edges are very distinct, and decrease it if the edges are blurry or have low contrast. You can adjust this setting while working.
* Frequency: Controls the number of anchor points the tool places along the edge. A higher frequency (e.g., 50-100) will create a more precise selection but can also make the path more complex and harder to adjust. Start with a value around 50. Lower values (e.g., 20-30) create fewer anchor points, making the path smoother but potentially less accurate. You can adjust this setting while working.
* Tablet Pressure: If you are using a drawing tablet, you can enable or disable the "Tablet Pressure for Size" option. This will allow you to control the width of the selection edge dynamically using the pressure sensitivity of your tablet pen.
5. Carefully Trace the Subject:
* Click once on the edge of your subject to start the selection.
* Slowly move the Magnetic Lasso Tool around the outline of your subject. The tool will automatically snap to edges as you move.
* *Important*: If the tool makes a mistake, don't panic! You can either:
* Press the Delete (or Backspace) key to remove the last anchor point and backtrack.
* Hold down the Alt (Option on Mac) key: This will change the Magnetic Lasso Tool into a regular Lasso Tool, allowing you to manually add straight line segments if the automatic edge detection is failing. Click to place anchor points manually while holding Alt/Option. Release Alt/Option to return to Magnetic Lasso mode.
* Zoom in for detail work: Use `Ctrl + +` (or `Cmd + +` on Mac) to zoom in for more accurate selections around hair, clothing details, etc. Zoom out with `Ctrl + -` (or `Cmd + -`). Use the Hand tool (press `H`) to move around the image while zoomed in.
* Close the Selection: When you reach the starting point of your selection, the cursor will change to include a small circle. Click to close the selection.
6. Refine the Selection (Critical):
* Go to `Select > Select and Mask`. This opens a dedicated workspace for refining selections.
* View Mode: Choose a view mode that helps you see the selection edge clearly. "Overlay" (red mask) is often a good choice.
* Global Refinements:
* Opacity: Adjust this to clearly view your selection.
* Smooth: This reduces irregularities in the selection edge, making it smoother. Increase it slightly.
* Feather: This softens the selection edge, creating a more natural transition between the subject and the background. A small feather radius (e.g., 0.5-1.5 pixels) is usually sufficient. Too much feather will create a blurred halo.
* Contrast: Increasing the contrast can sharpen the selection edge.
* Shift Edge: A negative value shrinks the selection, while a positive value expands it. Adjust this carefully to fine-tune the edge and eliminate any unwanted background around the subject.
* Tools:
* Refine Edge Brush Tool (R): This is the most important tool for refining hair and other complex edges. Paint along the edge of the hair to let Photoshop better identify and select the hair strands. Adjust the brush size ([ and ] keys).
* Brush Tool (B): Use this to manually add or subtract from the selection. Set the brush mode to "+" (add) or "-" (subtract) in the options bar.
* Output Settings:
* Output To: Choose "New Layer with Layer Mask". This will create a new layer containing only your selected subject, with a layer mask defining the selection.
* Click "OK" to apply the refined selection.
7. Select the Background:
* In the Layers panel, select the original background layer (or the duplicated "Subject Selection" layer if you didn't create a new layer with the layer mask). Make sure you're *not* selecting the layer with the layer mask. You want to be working on the layer containing the entire image.
* Go to `Select > Inverse`. This inverts the selection, so now the background is selected.
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 small radius (e.g., 2-5 pixels) creates a subtle blur, while a larger radius creates a more pronounced blur. Experiment to find the amount of blur that looks best for your image.
* Click "OK".
9. Adjust the Blur (Optional):
* If you want to adjust the blur later, you can convert the layer into a Smart Object *before* applying the Gaussian Blur.
* Select the background layer.
* Go to `Filter > Convert for Smart Filters`.
* Then apply the Gaussian Blur as in step 8.
* Now, the Gaussian Blur will appear as a "Smart Filter" under the layer in the Layers panel. You can double-click on the Gaussian Blur Smart Filter to adjust the radius at any time.
Tips and Considerations:
* Practice Makes Perfect: The Magnetic Lasso Tool takes practice. Don't get discouraged if your first attempt isn't perfect. Experiment with the settings and refine your technique.
* High-Resolution Images: Working with high-resolution images will yield better results.
* Background Complexity: The more complex the background, the more challenging the selection process will be. Consider using more advanced selection techniques (e.g., Pen Tool, Channels) for very complex backgrounds.
* Feathering: Use feathering sparingly. Too much feathering can create a noticeable halo around the subject.
* Layer Masks: Layer masks are powerful. You can edit them at any time to refine the selection. Paint with black to hide areas and white to reveal areas.
* Alternative Blur Filters: Experiment with other blur filters, such as "Field Blur," "Iris Blur," or "Tilt-Shift," for different effects. "Iris Blur" is particularly well-suited for portrait backgrounds, as it allows you to define a focal point and gradually increase the blur away from that point.
* Non-Destructive Workflow: Using duplicate layers and layer masks allows you to experiment without permanently altering your original image. This is a best practice in Photoshop.
* Consider Content Aware Fill: If you have distracting elements *close* to your subject, consider using Content-Aware Fill (Edit > Fill > Content-Aware) *before* you blur to remove them and make the blur look more natural.
Example Scenario:
Let's say you have a portrait of a person standing in front of a busy street. You want to blur the street scene to make the person stand out more.
1. Open the image in Photoshop.
2. Duplicate the background layer.
3. Select the Magnetic Lasso Tool.
4. Configure the tool with a Width of 10 pixels, Contrast of 15%, and Frequency of 50.
5. Carefully trace the person's outline.
6. Use "Select and Mask" to refine the selection, paying close attention to the hair. Use the Refine Edge Brush Tool for this.
7. Select the original background layer.
8. Inverse the selection to select the street scene.
9. Apply a Gaussian Blur with a radius of 4 pixels.
10. Adjust the blur radius if needed.
By following these steps, you can effectively blur the background of your portrait and create a more visually appealing image. Remember to practice and experiment with different settings to achieve the best results.