ABSTRACT
Drawn selections using the Lasso Tools Select by encircling or drawing around the area you wish to select. The standard Lasso Tool works like a pencil, allowing the user to draw freehand shapes for selections. A large screen and a mouse in good condition (or a graphics tablet) are required to use the Freehand Lasso Tool effectively. In contrast, the Polygonal Lasso Tool draws straight-edged lines between mouse-click points. Either of these features can be used to outline and select irregular-shaped image parts. A third tool, the Magnetic Lasso, helps with the drawing process by aligning the outline with the edge of objects automatically. It uses contrast in color and tone as a basis for determining the edge of an object. The accuracy of the ‘magnetic’ features of this tool is determined by three settings in the tool’s Options bar. Contrast is the value that a pixel has to differ from its neighbor to be considered an edge, Width is the number of pixels either side of the pointer that are sampled in the edge determination process and Frequency is the distance between fastening points in the outline. Double-clicking the Polygonal Lasso Tool or Magnetic Lasso Tool automatically completes the selection using a straight line between the last selected point and the first.
