Selecting > Making pixel selections > Using the lasso, polygonal lasso, and magnetic lasso tools
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Using the lasso, polygonal lasso, and magnetic lasso tools


The lasso and polygonal lasso tools let you draw both straight-edged and freehand segments of a selection border. With the magnetic lasso tool, the border snaps to the edges of defined areas in the image.

The magnetic lasso tool is especially useful for quickly selecting objects with complex edges set against high-contrast backgrounds.

To use the lasso tool:

1 Select the lasso tool (), and select options. (See Setting options for the lasso, polygonal lasso, and magnetic lasso tools.)

2 Drag to draw a freehand selection border.

3 To draw a straight-edged selection border, hold down Alt (Windows) or Option (Mac OS), and click where segments should begin and end. You can switch between drawing freehand and straight-edged segments.

4 To close the selection border, release the mouse without holding down Alt (Windows) or Option (Mac OS).

To use the polygonal lasso tool:

1 Select the polygonal lasso tool (), and select options. (See Setting options for the lasso, polygonal lasso, and magnetic lasso tools.)

2 Click in the image to set the starting point.

3 Do one or more of the following:
  • To draw a straight segment, position the pointer where you want the first straight segment to end, and click. Continue clicking to set endpoints for subsequent segments.
  • To draw a freehand segment, hold down Alt (Windows) or Option (Mac OS), and drag. When finished, release Alt or Option and the mouse button.
  • To erase recently drawn straight segments, press the Delete key.

    • 4 Close the selection border:
  • Position the polygonal lasso tool pointer over the starting point (a closed circle appears next to the pointer), and click.
  • If the pointer is not over the starting point, double-click the polygonal lasso tool pointer, or Ctrl-click (Windows) or Command-click (Mac OS).

    • To use the magnetic lasso tool:

    1 Select the magnetic lasso tool (), and select options. (See Setting options for the lasso, polygonal lasso, and magnetic lasso tools.)

    2 Click in the image to set the first fastening point. Fastening points anchor the selection border in place.

    3 To draw a freehand segment, move the pointer along the edge you want to trace. (You can also drag with the mouse button depressed.)

    The most recent segment of the selection border remains active. As you move the pointer, the active segment snaps to the strongest edge in the image, based on the detection Width set in the options bar. Periodically, the magnetic lasso tool adds fastening points to the selection border to anchor previous segments.

    4 If the border doesn't snap to the desired edge, click once to add a fastening point manually. Continue to trace the edge, and add fastening points as needed.

    5 To switch temporarily to the other lasso tools, do one of the following:
  • To activate the lasso tool, hold down Alt (Windows) or Option (Mac OS), and drag with the mouse button depressed.
  • To activate the polygonal lasso tool, hold down Alt (Windows) or Option (Mac OS), and click.

    • 6 To erase recently drawn segments and fastening points, press the Delete key until you've erased the fastening points for the desired segment.

    7 Close the selection border:
  • To close the border with a freehand magnetic segment, double-click, press Enter or Return, or click anywhere outside the document window.
  • To close the border with a straight segment, hold down Alt (Windows) or Option (Mac OS), and double-click.
  • To close the border, drag back over the starting point and click.
  • To close the border, click anywhere outside the active window.

    • Selecting > Making pixel selections > Using the lasso, polygonal lasso, and magnetic lasso tools