Use these tips to make the most of this key Photoshop tool
By Lewis Kemper
Working in an image-editing program without utilizing Layers is, from my perspective, like using a pro SLR and leaving it on manual all the time. You'll still be able to make quality images, but you certainly won't be taking advantage of all the technology that makes life easier! While most photographers have adapted to the new technology in their cameras, such as autofocus, multiple-exposure modes and motordrives, many photographers still use image-editing software without enjoying the benefits of Layers. Like autofocus, though, once you start using Layers, you probably won't go back to your old ways.
What Is A Layer? Think of a layer as a clear sheet of acetate over your photo. On this layer, you can add pixels in the form of image information—like paint on the acetate. Wherever there are no pixels (or "paint"), the layer remains transparent, and you can view the underlying layer or layers.
You can create multiple layers, remove layers, hide all or part of a layer, rearrange the order of layers, edit layers and blend the pixels of one layer into another in a variety of ways that give you different effects. These options all give you a lot of control and freedom when working on an image.
Adjustment Layers Besides pixel layers, you can have adjustment layers and vector or type layers, depending on the program you're using. Adjustment layers are empty layers that contain no pixels, yet they contain instructions that affect the appearance of underlying layers; they're like a filter on a camera's lens. They're used to make color adjustments to other layers without actually altering those layers.
Since adjustment layers contain information but not pixels, they can be edited, changing the adjustments as needed. You're able to make as many changes to the adjustments as you want because the effects of an adjustment layer don't become permanent until you flatten an image.
The advantage of using an adjustment layer is simple. Every time you adjust colors, contrast, brightness, saturation, etc., to the image itself, you're altering the pixels in your original image. The more changes, the more the pixels are altered, and the worse the quality of your image. Adjustment layers let you make those changes without altering pixels.