Create Selections with Photoshop CS5 Marquee Tool
Use Photoshop selection tools to make retouched images look real, not contrived . The Marquee tool is the main selection tool; by that, we mean that you use it most often for creating selections.
The Marquee tool includes the Rectangular Marquee (for creating rectangular selections), Elliptical Marquee (for creating round or elliptical selections), and Single Row Marquee or Single Column Marquee tools (for creating a selection of a single row or column of pixels). You can access these other Marquee tools by holding down the default Rectangle Marquee tool in the Tools panel.
To create a selection, select one of the Marquee tools (remember that you can press M) and then drag anywhere on your image. When you release the mouse button, you create an active selection area. When you’re working on an active selection area, whichever effects you choose are applied to the whole selection.
How you make a selection is important because it determines how realistic your edits appear on the image. You can use these tips and tricks when creating both rectangular and elliptical selections:
Add to a selection by holding down the Shift key; drag to create a second selection that intersects the original selection. The two selections become one big selection.
Delete from an existing selection by holding down the Alt (Windows) or Option (Mac) key and then drag to create a second selection that intersects the original selection where you want to take away from the original selection.You can add to and delete from selections.
Constrain a rectangle or an ellipse to a square or circle by Shift+dragging; make sure that you release the mouse button before you release the Shift key. Holding down the Shift key makes a square or circle only when there are no other selections. (Otherwise, it adds to the selection.)
Make the selection from the center by Alt+dragging (Windows) or Option+dragging (Mac); make sure that you release the mouse button before releasing the Alt (Windows) or Option (Mac) key.
Create a square or circle from the center outward by Alt+Shift+dragging (Windows) or Option+Shift+dragging (Mac). Again, make sure that you always release the mouse button before releasing the modifier keys.
When making a selection, hold down the spacebar before releasing the mouse button to drag the selection to another location.
To deselect an area, you have three choices:
Press Ctrl+D (Windows) or Command+D (Mac).
While using a selection tool, click outside the selection area.