Photoshop CS4: The Missing Manual

Chapter 3. Layers: The Key to Nondestructive Editing

Photoshop gives you two ways to edit your files: the destructive way and the nondestructive way. Destructive editing means you’re changing your original image—once you exceed the limit of your History panel (The History Brush), those changes are (gulp) permanent. Nondestructive editing means you’re not changing the original file and you can go back to it at any time. Folks new to image editing tend to use the first method and experienced pixel-jockeys the second—and you’ll likely see a tiny cloud of smugness floating above the pixel-jockeys.

When you’re working in Photoshop, you need to keep your documents as flexible as possible. People (even you!) change their minds hourly about what looks good, what they want, and where they want it—all of which is no big deal if you’re prepared for that. If not, you’ll spend a ton of time redoing what you’ve done from scratch. To avoid this kind of suffering, you can use layers, a set of stackable transparencies that together form your whole image (see Figure 3-1). Layers are your key to nondestructive editing.

With layers, you can make all kinds of changes to your image without altering the original. For example, you can use one layer to color-correct your family reunion photo (Fixing Color), another to whiten Aunt Bessie’s teeth (Whitening Teeth), and yet another to add a photo of the Great Pyramid, making your reunion look like it was in Egypt instead of the local park (Sky Swapping). Using ...