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Adobe Photoshop Lasso Tools

The lasso tools are the Adobe Photoshop freehand selection tools. They allow you to draw both straight-edged and freehand segments of a selection border. These tools are used to draw complex selections in the image that you are working on. The lasso tools are very useful in isolating complex portions of your image such as cutting out complex shapes such as subjects that you want to isolate from the rest of the image. For instance, you can remove the subject from the image and replacing it on a different background.
You can activate the lasso tool by clicking L on the keyboard. Cycle through the tools by using Shift + L.
The Lasso Tools consist of three different tools:
Lasso Tool [L]

The Lasso Tool is used to draw a selection around the part of the image that you want to isolate. It works muck like drawing with a pen around the outside of the image. Drag to draw a freehand selection border. 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. To erase recently drawn segments, hold down the Delete key until you've erased the fastening points for the desired segment. To close the selection border, release the mouse without holding down Alt (Windows) or Option (Mac OS).

Polygon Lasso Tool [L]

The Polygon Lasso Tool allows for more precise selections than the normal lasso tool. Click in the image to set the starting point. 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. To 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).

Magnetic Lasso Tool [L]

The Magnetic Lasso Tool is especially useful for quickly selecting objects with complex edges set against high-contrast backgrounds. Click in the image to set the first fastening point. Fastening points anchor the selection border in place.
     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. 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.
     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.
     To erase recently drawn segments and fastening points, press the Delete key until you've erased the fastening points for the desired segment.
      To close the border with a freehand magnetic segment, double-click, or press Enter or Return. 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.
Lasso Toolbar

The lasso tool options let you customize how the different lasso tools detect and select edges. The first button allows you to specify whether to add a new selection. The next button will add to an existing selection. The third button will subtract from a selection. And the final button allows you to select an area intersected by other selections. You can also specify feather and anti-aliasing options.
The magnetic lasso has a few more options than the other two lasso tools: Magnetic Lasso Options

     To specify a detection width, enter a pixel value for Width. The magnetic lasso detects edges only within the specified distance from the pointer.
     To specify the lasso's sensitivity to edges in the image, enter a value between 1% and 100% for Edge Contrast. A higher value detects only edges that contrast sharply with their surroundings; a lower value detects lower-contrast edges.
     To specify the rate at which the lasso sets fastening points, enter a value between 0 and 100 for Frequency. A higher value anchors the selection border in place more quickly.
     On an image with well-defined edges, try a higher width and higher edge contrast, and trace the border roughly. On an image with softer edges, try a lower width and lower edge contrast, and trace the border more precisely.
     To change the lasso cursor to indicate the lasso width, press the Caps Lock key on the keyboard. Change the cursor while the tool is selected but not in use.
     If you are working with a stylus tablet, select or deselect the Stylus Pressure option. When the option is selected, an increase in stylus pressure will cause the edge width to decrease.
      While creating a selection, you can press ] to increase the magnetic lasso edge width by 1 pixel; press [ to decrease the width by 1 pixel.

Next...The Magic Wand Tool

Author: AB

Date created: December 19, 2002