Adding a Perfectly Square or Circular Selection in Photoshop

To add a perfectly square or round selection to an existing selection, follow these steps:

1. Press Shift and drag with the Rectangular or Elliptical Marquee tool.
Your selection is unconstrained.
2. As you drag, keeping your mouse button pressed down, release the Shift key for just a moment, and then press it down again.
Your unconstrained selection suddenly snaps into a constrained square or circle.
3. Release the mouse button before you release the Shift key.
If you don’t release the mouse button before you release the Shift key, the selection shape will revert back to its unconstrained form.

Deleting from an existing selection while drawing from the center out

To delete part of a selection while drawing from the center out, follow these steps:

1. Press Alt (Option on the Mac) and drag with the Rectangular or Elliptical Marquee tool.
2. As you drag, keeping your mouse button pressed down, release the Alt (Option on the Mac) key for just a moment, and then press it down again.
You are now drawing from the center outward.
3. Release the mouse button before you release the Alt (Option on the Mac) key.

Use this technique when you’re selecting a doughnut, tire, inflatable swim ring, and other circular items with holes in the middle.

Intersecting Two Selections in Photoshop

What happens when you press the Shift and Alt (Option on the Mac) keys together? Not a collision, but an intersection. Pressing both keys while dragging with a Lasso or Marquee tool or clicking with the Magic Wand tool creates the intersection of the original selection with the second selection.

To retain only the part of an image where two selections overlap, press Shift and Alt (or Shift and Option on the Mac) and then drag.

You can select a portion of an image with a tool such as the Polygon Lasso tool. Then press the Shift and Alt (Option on the Mac) keys at the same time and drag with the Rectangular Marquee tool.

Getting the Keys to Behave
Photoshop has a little glitch in its way of doing things. Well, not so much of a glitch as a conflict.
With so many ways of doing things with Photoshop, it’s no wonder that somewhere along the line you have to jigger with Photoshop to get it to do what you want. For example, how does Photoshop know whether you want to create a perfect square or add to a selection when you press the Shift key?

Let me lay this out for you:
-When you make an initial selection with the Rectangular or Elliptical Marquee tool, pressing the Shift key constrains the proportions of the selection, thereby allowing you to create a perfect square or a perfect circle.

-If you press Alt (Option on the Mac) with either of these tools, you can draw from the center out.

-If you press Alt (Option on the Mac) with the Lasso tool, the Lasso temporarily becomes the Polygon Lasso tool.

Unfortunately, despite numerous requests, the ability to read users’ minds wasn’t a Version CS upgrade feature. The following sections show you what you have to do to get Photoshop to recognize your wishes.