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Photoshop

Selections

Lasso Tool

The Lasso tool has three variations: the Lasso tool itself, the Polygonal Lasso tool and the Magnetic Lasso tool.

Lasso Tool

The Lasso tool will draw a freehand selection around a portion of an image. To select the Lasso tool you can click on the tool in the Toolbox or use its keyboard shortcut L. A selection is created by holding down the mouse button on the image while dragging around the area you want to enclose in a selection. Once you circle back to your starting point, releasing the mouse button will complete the selection. Select the Lasso tool and draw a selection around the entire cat.

Lasso Tool Options

Selection Options

These four buttons allow you to:

• create a new selection,
• add to a selection,
• subtract from a selection, or
• intersect with another selection.
  

Feather

Entering a pixel value in this field will apply a feather to your selection. Feathering will soften or blend the edges of a selection by the distance you've entered. With a value of 0, no feathering will be applied.

Anti-Alias

This option will apply anti-aliasing to the selection that you draw. Anti-aliasing will provide a smooth and crisp edge around the selection.

Polygonal Lasso Tool

The Polygonal Lasso tool draws its selections when you click on points around the image. The tool will automatically draw straight lines between each pair of points. The selection is completed when you double-click on the starting point. Try drawing a selection around the cat with this tool.

Polygonal Lasso Tool Options

The tool options are the same as those described above for the Lasso tool.

Magnetic Lasso Tool

The Magnetic Lasso tool will detect the border between contrasting colours. When you drag your cursor around objects in an image the selection will snap to this border. Alternately, you can click once at the point where you want the selection to start and move your cursor over the edges of the object without holding down the mouse button. To finish your selection, click on the starting point. Select this tool and draw a selection around the cat again and compare it with the level of patience and difficulty required with the other tools for the same selection.

The example at the right shows a selection in progress using the Magnetic Lasso tool. Notice that there are small squares every so often along the path created. These are called anchor (or fastening) points and they are inserted by the Magnetic Lasso tool at strong edges of the image. The most recently-placed anchor point has a solid white fill while the previous points are hollow. As you are moving around the object, you can remove the most recently-added path and anchor point by pressing the Backspace (Delete) key. You can continue removing points by pressing the Backspace (Delete) key until you've removed the desired segments of the selection path. Then you can start selecting again from that point.

Magnetic Lasso Tool Options

The Selection Options, Feather, and Anti-alias options are the same as those described above for the Lasso tool. This tool has additional options that let you customize its sensitivity.

Width

This field defines the radius around the pointer that will be examined to locate an edge. The range is anywhere between 1-40 pixels.

Contrast

This option lets you set the amount of contrast the Magnetic Lasso should evaluate when looking for an edge. The values can range between 1%-100%. A lesser value detects a softer edge; a higher value detects a sharper edge.

Frequency

The Frequency setting determines how frequently anchor points will be placed in creating the selection. The range for this setting is between 1-100. A higher value sets the points closer together.

Stylus Pressure

When using a pressure-sensitive tablet, enabling this activates the ability to adjust the size of the tool's tip. More pressure will create a larger tip.

Lasso Tool Summary

• The Lasso tool has three variations: the Lasso tool itself, the Polygonal Lasso tool and the Magnetic Lasso tool.
• The Lasso tool lets you draw a freehand selection around a portion of an image.
• The Polygonal Lasso tool draws straight-line selection paths between the points you click on the image.
• The Magnetic Lasso tool can detect the boundary where two different colours meet to help make selections in a more automatic manner.
• All three tools have the Selection Options, Feather, and Anti-alias options. In addition to these, the Magnetic Lasso tool has Width, Contrast, Frequency and Stylus Pressure options.

Lasso Tool Keyboard Shortcuts:

• Lasso tool: L

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Photoshop - TOC - Introduction - Books -
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Photoshop - TOC - Introduction - Books -
Selections - Links - Questions -
1 - [ 2 ] - 3 - 4 - 5 - 6 - 7 -