Photoshop. For photographers, web developers and graphic designers alike, its the go-to program for creating and editing professional grade graphics. And like every beloved piece of software, it has to have a strong foundation to build upon; a base system that supports all other operations. For Photoshop, it's layers.
Operations we describe here are performed using Adobe Photoshop CS5, but are applicable to all Creative Suite versions of the software.
A Layer's purpose in life
Layers are Photoshop's way of organizing the content being produced within the software. They allow us to keep related content separate, and to make it easier for us to edit that content later. It's almost impossible to imagine using the software in the days before layers were implemented.
Without layers, all content in an image would exist on the same plane; that is, any change applied to the image would affect the entire image, and there would be no way to easily modify a particular object, especially if that object overlapped other objects.
Imagine an image of two circles, one red, and one blue. If you needed the circles to partially overlap, you'd need to draw the circles precisely in their proper positions. Once the circles were in place, it would be difficult or impossible to edit them separately.
Enter layers. Since Photoshop 3, we have had the ability to place content or groups of content on separate layers, and those layers can be moved and edited separately. Even more helpful, these layers can now be organized further into folders, and can be modified with nondestructive adjustment layers.
In our example above, we place each circle on its own layer. We can then perform independent actions on them, as well as move them around however we wish.
Creating and manipulating layers
The layers panel (Window > Layers) shows us all layers in the current image. This panel will also display the order of the layers, and any grouping, linking, or Smart Objects, which are special layers that contain multiple layers of content that can be modified non-destructively. A layer can be created by clicking the New Layer icon on the layers panel, or by clicking Layer > New > Layer.
Organizing your layers
One of the advantages of the layer system in Photoshop is the ability to keep them organized. This comes in handy when a project gets large and you've got layers coming out of your ears. We have a few options to satisfy our obsessive/compulsive tendencies, fortunately.
- Linking Layers
Sometimes several layers of content need to be grouped together, without actually merging them. This is where linking comes in handy. Layers can be linked together by selecting two or more layers (Click layers while holding down Control/Command) and then right clicking the layers and selecting "Link Layers". Any layers can be unlinked the same way. Linked layers can be moved around together.
- Layer Groups
Layer groups give us even more control over the way our objects are organized. A new group can be created by clicking the New Layer Group icon at the bottom of the layer panel or by clicking Layer > New > Group. Selecting two or more layers and clicking the New Layer Group icon will place those layers together in a new layer group automatically.
- Smart Objects
Grouping layers into a Smart Object allows us to apply non-destructive adjustments to them simultaneously. This means that actual pixels in the image will not be effected, and the results can be reversed easily. We can convert layers over to a Smart Object by selecting two or more layers and then right-clicking them to bring up a contextual menu, then selecting Convert to Smart Object.Similarly, we can use the menus and click-through to Layer > Smart Objects > Convert to Smart Objects.Smart objects can then have adjustments and filters applied to them, and can then be reversed if necessary. We also have the ability to convert the contents of a Smart Object to a standard layer (which is required to perform any pixel-altering functions) by clicking Layer > Rasterize > Smart Object.
Editing layers and adjustments
One of the most useful things about layers is the ability to edit them individually. We might have an image consisting of several layers, all of which could have different needs such as opacity changes, masking, or other adjustments.
Masks can be applied to individual layers by clicking the Layer Mask button at the bottom of the panel or by clicking Layer > Layer Mask > Hide All/Reveal All. This creates a new mask that is attached to that layer, and allows us to modify the mask independently. You can click the thumbnails within the layer to select either the mask or the layer itself.
Adjustment layers allow nondestructive adjustments such as levels and curves to the their affected layers, and can be turned off or deleted at any time. These can be added by clicking Layer > New Adjustment Layer and then selecting what adjustment you'd like to apply. Fill layers work in the same way. These layers affect all layers below them.
Any and all layers can also be locked by clicking the small lock icon near the top of the layer panel. Locked panels can not be moved or edited.
Lastly, any layer can be hidden from view temporarily by clicking the small corresponding eye icon on the left hand edge of the panel.
Blending, opacity, and layer styles
Photoshop has grown exponentially over the years and continually add features that make it easier for us as designers to create the images we've envisioned. Layer styles are a good example of these additions. Now, we don't have to experiment and go through the rigors of trial and error (wait, where's the fun in that?) to apply effects to our images. We now have a dedicated panel (Window > Styles) that gives us a set of predefined styles to apply to our layers, simplifying the process of creating buttons, interfaces, and other graphics.
Using a layer style is as simple as clicking on a layer, and then clicking a style thumbnail in the Layer Styles panel. The image will instantly update, showing its new look. The layer in the Layers panel will also provide an indented list of what specific effects were applied to make that look possible. Each individual effect can be adjusted, or turned off altogether.
Finally, we have the ability to control the opacity and blending of each layer. Opacity refers to the level of transparency for a layer. When a layer is selected, its opacity and fill percentages are displayed near the top of the panel, and can be adjusted independently. Layer blending settings are available as well at the top of the panel, and let us blend individual layers into the rest of the image with several presets.
Go Play Around!
We've only scratched the surface of how powerful and important layers are to our workflow in Photoshop; luckily for us, the best way to learn how to use the software is by applying what you have learned, so crack it open and give it a shot!
You can delve deeper into the world of Photoshop by checking out some of our other related articles here on Photodoto such as making the popular Earlybird Instagram filter and Ann Davlin's excellent series on retouching in Photoshop. Photoshop.com is also a great online tool created by Adobe that helps you along in learning about the software as well as improving and sharing your images.