When working with Photoshop, you will use selections all the time. Selections are areas of an image that you choose to isolate from the rest of the image to make modifications to, or to copy and paste into other images (or even the same image again). You can also start with a new layer and use selections as a drawing tool. A fancy effect that selections are famous for is replacing heads! With a little practice you can, for example, select your head and place it into another body seamlessly. Or at least in this example, semi-seamlessly!
A "marquee" is a moving, dotted line in the shape of your selection. It's also called the "selection path," and sometimes informally called the "ant trail."
When working with a selection within an image, changes can be made only within that selection. In this example, a circular selection has been made and color has been applied. As you can see, the paint only appears inside the circle selection.
To create a selection, first select the desired Marquee tool. Then click on the upper-left portion of the area you want to select and drag the mouse down and and to the right until you reach the desired dimensions. By holding down while dragging, you are constraining the proportions evenly, which will create a perfect square or a perfect circle. By holding down (Windows) or (Mac OS) while dragging, the selection will expand evently outwards from a central point.
As detailed below, Marquee tools include a Rectangular Marquee tool (default), which makes square and rectangular selections. The Elliptical Marquee tool makes circular and oval type selections. The Single Row Marquee and Single Column Marquee tools select a single row or column of pixels.
|The default Rectangular Marquee tool||Three additional Marquee tools are available when you click and hold down the default tool button in the toolbox.|
|The default Lasso tool||Three additional Lasso tools are available when you click and hold down the default tool button in the toolbox.|
|The Magic Wand tool|
It's possible to select and deselect more than one portion of the already existing selection. Located in the left side of the Marquee toolbar are four buttons that enable you to, from left, select normally, add to a selection, subtract from a selectio, and intersect with a selection. There are also key combinations that enable the same options. By holding down after a selection has already been made, you can add to that selection. A tiny plus sign appears next to the mouse pointer, and the Addition button in the Marquee toolbar will be highlighted. By holding down (Windows) or (Mac OS), on the other hand, you can subtract from a current selection. A tiny minus sign appears next to the mouse pointer, and the Subtraction button in the Marquee toolbar will be highlighted.
Advanced Selection Tools
The Lasso, Polygonal Lasso, and Magnetic Lasso Tools
The Lasso tool allows "freehand" selection controlled by the movement of the mouse. The Polygonal Lasso tool lets you draw straight-edged segments of a selection border. The Magnetic Lasso tool snaps the selection border to the edges of defined areas in the image. This can be very powerful.
The Magic Wand Tool
The Magic Wand tool works similar to the Magnetic Lasso tool in that it can be used to select highly defined areas. The way the Magic Wand tool works is to select an area of similar colors: for example, to select only a red ball lying on green grass. What's great about the tool is that there is no need to trace the outline of the ball by hand. Just click anywhere where in the red area the tool will automatically select similar shades of that color. You can change the "tolerance level," or how tolerant the tool will be in selecting "similar" shades. Selecting a low number (the scale is from 0 to 255) will make the Magic Wand tool select only colors that are very similar to the one you selected. Higher numbers will broaden the range of selection.