Chapter 3. Layers: The Key to Nondestructive Editing
Photoshop gives you two ways to edit files: destructively and nondestructively. Destructive editing means you’re changing the original image—once you exceed the History panel’s limit (Changing How Far Back You Can Go) and save your document, 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 latter.
When you’re working in Photoshop, it’s best 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. But if you’re not, you’ll spend a ton of time redoing what you’ve already done from scratch. To avoid that kind of suffering, you can use layers, a set of stackable transparencies that together form a whole image (see Figure 3-1). Layers are your ticket to nondestructive and therefore safer, non-committal editing. (If only we had layers in real life!)
Another argument for using layers is that they let you easily apply the same effect you’re creating in one image to other images (by dragging and dropping the relevant layers into another open document), as well as reverse-engineer a technique or effect that you created years ago in ...