Adobe Photoshop Basics

In this lesson we're going to be exploring all of Photoshop's selection tools plus masks, alpha channels, and transformation of selections. The selection tools include the marquee tools, the lasso tools, and the magic wand. However, we are also going to discuss many more ways of making and refining selections using Quick Mask Mode, alpha channels, and the transform selection command.

We use selections in Photoshop to isolate editing to specific areas in an image, or for cutting out portions of an image. Similarly, masks are used to protect specific image areas from being modified, or for removing portions of an image. For a more thorough overview on the differences between masks and selections, see part two of my article, All About Masks.

Unless you're entirely new to Photoshop, you probably have some familiarity with the marquee selection tools. It's difficult to do much of anything in Photoshop without them. These include the rectangular marquee, the elliptical marquee, the single row horizontal, and single row vertical marquee tools. As you learned in a previous lesson, the shortcut key for the marquee tools is M and Shift+M toggles the rectangular and elliptical marquee tools. Let's look at some additional shortcuts for the marquee tools:

• Holding down the shift key while dragging a selection marquee constrains the selection to a square or circle.
• Holding down the shift key while dragging a selection marquee when an existing selection is active adds to the selection.
• Holding down the Alt/Option key while dragging a selection marquee when an existing selection is active subtracts from the selection.
• Holding down the Alt/Option key while dragging a selection marquee creates the selection from the center out from where you initially clicked.
• The Shift and Alt/Option modifier keys can be used together when making an initial selection to constrain proportions and draw from the center.
• The Shift and Alt/Option modifier keys can be used together when another selection is active to create a selection from the intersection (the areas where the two selections overlap).
• To reposition a selection while you are in the process of drawing it, hold down the spacebar. As long as the spacebar is held down you can move you selection, when you let up on the space bar you can go back to drawing your selection. The selection will not be finalized until you release the mouse button.
• You can move a selection after it has been finalized by moving the cursor inside the selection marquee as long as the marquee tool is active. The cursor will change to look like this and then you can click and drag the marquee into a new position. You can also use the arrows on your keyboard to reposition a selection.
• Ctrl/Command-A selects the entire image.
• Ctrl/Command-D removes the selection.
• Shift-Ctrl/Command-I inverts the selection.
• Ctrl/Command-H acts as a toggle to hide the marquee but preserves the selection.

The marquee tools have some options you can access by double clicking the tool to bring the options palette to the front. You can adjust the feathering, anti-aliasing, and style.

• Feathering lets you fade the edge of the selection, but in most cases you will leave this setting to zero since there are more accurate ways of feathering a selection after it has been drawn.
• Anti-aliasing smoothes out the edges of the selection. You'll rarely, if ever, need to deactivate this. It will be unavailable for the rectangle selection tool because rectangles always have hard edges.
• The style menu lets you make more precise selections.
  • When constrained aspect ratio is chosen you can choose the ratio of width to height. With both values set to 1 you would only be able to draw a perfect square or circle. With a width of 1 and a height of 2 you would create a selection that is two times higher than the width, and so on.
  • When fixed width is chosen you can enter a width and height in pixels and just click once to make a selection of that exact size.

Take some time now to try all these options using the marquee selection tools. When you're ready, continue on to the next lesson on the lasso tools.

Next> Lasso & Wand Selection Tools