How to Use Photoshop’s Lasso Tool

1. Select a feathering amount.
2. Choose whether to use anti-alias.
3. Make the selection.
4. Modify the selection (optional).
5. Refine the selection.

Step 1: Select a Feathering Amount

What Feathering Amount Should You Use?

The amount of feathering you should use depends on what you intend to do with your selection and also on your personal preference. Some Photoshop users like to keep feathering settings to a bare minimum (1–5 pixels) because higher settings can make the effect look forced, or overly “Photoshopped.” If you intend only to move your selection to another part of an image (or even the same image) with a similar background, you might not need to use feathering at all. For instance, if you were simply moving the orange flower shown here to another part of the image with a pure black background, any feathering effect would be invisible and therefore unnecessary. If you were moving the same flower onto a white background, though, you’d want to use a feathering setting of at least 1–5 pixels to soften the edges of the selection somewhat.

 

 

Step 2: Choose Whether to Use Anti-Alias

Step 3: Make the Selection

• Surround the area: Click and drag the mouse around the part of the image that you want to select. You don’t need to trace the boundary of the selection area neatly—you can edit it later if you need to. Just be sure to surround every part of the image that you’d like to select.
• Complete the selection: Once you’ve surrounded the entire area and have returned to the point at which you started the selection, release the mouse button. Photoshop will complete the selection automatically. A line of “marching ants” will mark the selected area.
   
  
   
  

Using the Polygonal Lasso Tool to Make Polygonal Selections

• It can be surrounded by straight lines: Some selections are too detailed and amorphous to be captured with anything but a freehand selection.
• You don’t care how the selection boundary looks: If you plan to move your selection to another part of the image (or to another image) with the exact same background, the selection boundary won’t be visible, so you won’t care how the selection boundary looks. But if you plan to place your selection against a background that differs in any way from the selection’s current background, you’re probably better off making a freehand selection and feathering it a bit, rather than making a selection with polygonal lines.

1. Begin as you normally would: Click and start to make the selection by hand.
2. Switch to polygonal lasso mode: Whenever you encounter the part of your selection that you’d like to make with a straight line, click the Alt key (Option on a Mac) and release the mouse button. The cursor will switch from the Lasso tool’s icon to the Polygonal Lasso tool’s icon, which looks like an odd-shaped polygon.
3. Draw a straight line: Without releasing the Alt (Option) key and without clicking, drag the mouse to draw a straight line. Click the mouse button to mark the end point of your first line and the starting point of the next line. By using this approach, you can click around the entire selection.
4. Repeat step 3 until you surround the selection with a series of straight lines: When you reach the point at which you started the selection, release the Alt (Option) key. Photoshop will automatically complete the selection.

Note that at any point during the selection, you can switch back to standard Lasso mode by releasing the Alt (Option) key and then clicking and dragging as you normally would to make a freehand selection with the Lasso tool. To return to Polygonal Lasso mode, press the Alt (Option) key again and drag without clicking. In this way, you can make selections that have a combination of straight lines (to cover long edges of a selection quickly) and freehand-drawn lines (to get into difficult-to-reach areas of the selection).

 

Step 4. Modify Your Selection (Optional)

Once you’ve made a selection with the Lasso tool, you can add to it, subtract from it, or select the area in which it intersects with another selection. You can access each of these options by clicking the buttons on the left side of the Lasso toolbar.

 

• Add to a selection: Click the button in the Lasso toolbar, or hold down the Shift key. A tiny plus sign will appear next to the standard Lasso tool icon. Starting from any point outside the boundaries of the original selection, click and drag to select the area of the image that you’d like to add. Make sure to end your selection on any point along the boundary of the original selection. Photoshop will then add the new selection to the original selection.
   
  
   
  
• Subtract from a selection: Click the button in the Lasso toolbar, or hold down the Alt button on a PC or the Option button on a Mac. A tiny minus sign will appear next to the standard Lasso tool icon. Starting from any point outside the boundaries of the original selection, click and drag within the selection to select the area that you’d like to remove. With the mouse button still held down, move the cursor outside the selection and release the mouse button. For example, if your selection takes the form of a circle, you’d click outside the circle, drag the mouse over the area inside the circle that you’d like to remove from the selection, and then release the mouse button. Photoshop will then subtract the unwanted area from your original selection.
   
  
• Intersect with other selections: This option lets you select and repair the area in which two selections overlap. Photoshop selects only the overlapping portion of the selections and deselects any remaining portion of the selections. The Lasso tool then applies to the selected portion only. To use this feature, click the button in the Lasso toolbar, or hold down Alt+Shift on a PC or Option+Shift on a Mac.
   
  

To create an entirely new selection with the Lasso tool at any time, click the leftmost of the four buttons and then make your new selection.

 

Step 5: Refine the Selection (Optional)

If you’re using Photoshop CS3, you can use the new Refine Edge feature to fine-tune the edges of selections that you make with the Lasso tool. To use the Refine Edge feature, first make a complete selection (see steps 1–4). Once you’ve made a complete selection, click the Refine Edge button in the Lasso’s toolbar. The Refine Edge dialog box will pop up, and your selection will now appear isolated against a white background—the other elements in your image will vanish, but they’ll reappear once you close the Refine Edge dialog box. The dialog box allows you to refine and preview your selection.

 

Refining Selections

• Contract/Expand: Though this slider is located last in the Refine Edge dialog box, it’s often the most helpful. This slider lets you adjust the scale of the selection boundary. Moving the slider to the left (or entering a negative value) enlarges the boundary, and moving it to the right (or entering a positive value) contracts it. Settings range from –100 to +100.
• Radius: Lets you specify the region of the selection outside the selection boundary that the Refine Edge feature should also adjust. Settings range from 0–250 px.
• Contrast: Sharpens the edges of the selection boundary. Use lower settings for softer edges and higher settings for hard edges. Settings range from 0–100%.
• Smooth: Smooths out especially jagged portions of the selection boundary. Settings range from 0–100.
• Feather: Softens the transition between the selection boundary and the other pixels in the image. Settings range from 0–250 px.
   
  

The Refine Edge’s Preview Checkbox

The Refine Edge’s Background, Mask, and Quick Mask Preview Feature

At any point while you’re refining your selection, you can use the Refine Edge’s Background, Mask, and Quick Mask preview buttons to preview how your selection looks against various backgrounds, as a mask, or as a Quick Mask. The Refine Edge dialog box provides five preview options, each of which has its own icon: standard view, Quick Mask view, black background view, white background view, and mask view.

 

• Standard view: Shows the selection with its regular marching ants selection border. Any other pixels in the image will also be visible.
• Quick Mask view: Shows how the selection would appear as a Quick Mask. Double-click this preview option’s icon to adjust the Quick Mask’s settings.
• Black background view: Shows the selection against a black background.
• White background view: Shows the selection against a white background.
• Mask view: Shows the mask that surrounds the selection—the selection will appear white, and the pixels around it will appear black.