Understanding and controlling layers is key to tapping the power of Photoshop. Layers facilitate the process of combining images, adjusting the appearance of an image and so much more -- but let's begin with the basics.
An image in Photoshop can be composed of only one or two layers, but often it's composed of many. Think of a layer as a clear plastic rectangle like an acetate sheet to which you can add color, an object, a photo, a shape, or one of many other things. These rectangles or layers can be edited independently and are stacked to form a new image. Proficiency with layers empowers you to get the most out of your image.
An Example Image with Layers
The image below has three layers as shown in the Layers panel: the Background layer on the bottom of the stack, the Bird layer on top of the background layer, and the Oval layer on top of the Bird layer. At this point, the yellow oval is covering the bird because it's on the top of the stack, and it's larger than the bird. We'll look at a few ways to make the bird visible but first let's uncover a few details about the layers.
Background layer: A new file begins with a layer called "Background." If you open a photo, the photo becomes the Background layer. In this image the background is a simple white rectangle. The Background layer has characteristics that differ from other layers. Notice the lock icon on this layer in the Layers panel. The Background layer remains at the bottom of the stack. It can't be moved. It can't have transparency. Despite these restrictions on this special layer, it can be renamed to anything other than "Background" to function the same as another layer.
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Bird Layer: A new layer is created automatically when you copy and paste from one file into another, which is how the Bird layer here was created. The area surrounding the bird is transparent because only the bird was selected when copied. New layers begin with transparency.
Oval Layer: When you select New from the Layer menu, a new layer is created. The Oval layer was created like this and then a selection tool was used to create and fill the oval with yellow. The area surrounding the oval is transparent.
Some Ways to Manipulate Layers
Click on a layer in the Layers panel to make it the active layer. Only one layer is active at a time. Click the visibility icon (the eye) in front of a layer to temporarily hide that layer from view. Notice that when the Oval layer is hidden, the bird is in view. Click the box in front of a layer to turn the visibility back on. Click and drag through the visibility icons to hide or show several layers at once.
Change the order of the layers in the stack to control appearance. A layer at the top of the stack is in the front of the image. The bird becomes visible when it is brought to the top of the stack. In this case, the Bird layer is dragged above the Oval layer. A dark horizontal line appears to indicate the place to release it.
Some Ways to Create a New Layer
When you add a new layer, it is placed above the current layer. Hold down the Ctrl (Windows) or Command (Mac) key when you add a new layer to send it below the current layer.
- From the Layer menu, select New and then Layer.
- Paste a selection from the current image or from another image.
- Click the New Layer icon in the Layers panel.
- Press Shift-Ctrl-N.
- Make a selection on a layer, right-click and choose Layer via Copy or Layer via Cut.
Some Other Types of Layers
Other options in the Layer menu include New Fill Layer and New Adjustment Layer. Use these layers to experiment with effects like color and tone which apply to the layers below them in the stack or to a selected area. These layers do not actually change the pixels on the layers below them and can be deleted at any time. To add a Text layer, just start using the Text Tool, and a layer is created for you. Right-click on a layer in the Layers panel to see additional layer options including , Flatten, and Create Clipping Mask, which are different ways to merge or blend layers.
The Adobe Photoshop Help website provides more information on layers.