Join Jan Kabili for an in-depth discussion in this video What are the advantages of layers?, part of Photoshop CS4: Layers in Depth.
There are some real advantages to making use of layers when you are working in Photoshop. A major benefit of layers is that they allow you to isolate individual pieces of artwork and that means that you will be able to move and to edit the content of each layer independently without disturbing the rest of the image. For example, in this composition, I have the candies that you see here on a separate layer as represented by the candies layer in the Layers panel. To show you the content of this layer alone I'll hold the Option key on a Mac with the Alt key on a PC as I click on the eye icon to the left of the candies layer, and that shows you in the document window that there is content on this layer up here, and that the rest of the layer is transparent or semi-transparent. I'll Option or Alt- click again on the eye icon to the left of the candies layer to make the rest of the layers visible.
Being able to move the content of this or any layer independently of the rest of the image is an important benefit of using layers. To move just the candies for example, I first have to select the candies layer by clicking on that layer in the Layers panel. Then I'll go to the toolbox and I'll click on the very first tool, the Move tool, to select it. And then I'll come into the image, I'll click anywhere and I'll drag. I'm going to drag up. And notice that I didn't have to click directly on the candies that were showing in order to move the content of this layer because when you click-and-drag on a layer, the entire layer moves just one unit. When you drag with the Move tool, if you want to constrain the direction of the movement so that you don't inadvertently move left to right, if you're just trying to move directly then you can hold down the Shift key as you drag.
Notice that I push some of the content of the candies layer up off the top of the canvas. But that content isn't gone forever. If I want to get it back all I have to do is drag down in the other direction and it reappears. And that's true even if I were to save and close this image and then reopen it. I'm going to drag the candies up again to show you that the stars are now noticeable on top of the candies. That's because the candies layer is located beneath the stars layer in the stack of layers, and you can see that here if you look at the Layers panel. Here's the candies layer and above it is the stars layer.
I'll have more to say on this subject of stacking order later in this chapter. Moving the content of layers independently is a huge benefit of using layers. But it's not the only benefit that layers offer. Just as important is the fact that I can edit the content of each layer independently of the rest of the image. And when I say Edit I'm referring to almost anything you can do to content in Photoshop from adding a style to a text layer to dodging or burning a photo layer. To give you just a taste of what I mean, I perform a simple edit on one of the layers in this file. I'm going to select Layer 1 here, which is the layer that I added as a new layer in the preceding movie. To show you what's on Layer 1 I'll hold the Option or Alt key and click on the eye icon to the left of that layer, and you can see in the document window that this layer is composed primarily of transparent pixels. But it does have this small pink brush stroke at the bottom of the layer, which I added in the last movie.
I'll go back to the layer and I'll Option or Alt-click on its eye icon to bring back the rest of the layers. Because I want to edit the content of just this layer it's important to double-check that this layer is selected. In other words highlighted here in this Layers panel. I'll talk a lot more about selecting a layer in later movies. But now I'd like to show you one of the many things that I could do to this layer without affecting the other layers. So let's say for example, I want this pink stroke to be larger so it covers a little more of this area down here at the bottom right.
To do that I'll use the Transform command in Photoshop. The most direct way to transform layer content is to select the Move tool, which I already have selected in the toolbox, and then to go to the Move Tool Options bar up here and check this box next to Show Transform Controls. That displays these anchor points around the contents of the selected layer. I can click on any of these anchor points and drag to change the size and shape of this image. If I hold down the Shift key and click on one of the corner anchor points and then drag, that maintains the proportions of the original artwork as I resize it.
When I'm transforming bit-mapped or pixel-based artwork like this stroke I'm always careful not to make it too much bigger than the original or it will start to get blurry and at some point of it will begin to actually display the pixels that make up that content. When I'm done I have to commit this transformation and to do that I'll go up to the Options bar and I'll click the big check mark here on the right. And to make the anchor points disappear down here I'm going to go to the Options bar for the Move tool and un- check Show Transform Controls.
The take-home point of what I just did is that the changes I made to this content affected only the pink stroke on Layer 1. They didn't affect any other part of this image, and there are lots of other manipulations that I could make to this layer or to any layer without affecting the other layers in the file. I could add a filter, I could change the color of the content, I could add a layer style and lots more. You can start to see from the simple examples that I have showed you that being able to move and edit individual pieces of artwork in isolation from the rest of a Photoshop composition is a major benefit of using layers. I do want to mention that there are some other advantages of using layers that are associated with special kinds of layers. To give you just one example I have a type layer in this file and a type layer is a special kind of layer, in part because it remains editable.
So even if I were to save and close this file and then reopen it, I could change the look or the content of this type layer. I'll be talking about type layers in depth later also, but just to give you a quick look at how that would work I'm going to select the dreamy treats layer by clicking on that layer, and then I'm going to go to the toolbox and I'm going to select the Horizontal Type tool. Then I'll come into the image, I'll click just to the right of the last letter and drag over the other letters of that text. And now I'm going to type something different. I'll type sweet dreams and then I'll go up to the Options bar for the Type tool and I'll click the check mark to commit that edit.
That's just one example of an advantage associated with a special kind of layer. Later in the course I'll be covering lots more about type layers and introducing you to the advantages of other special layers including shape layers, Smart Object layers and some special layers in Photoshop CS4 Extended, video layers and 3D layers. So that gives you a look at some of the advantages that layers offer. Increase in file size due to layers is becoming less-and-less of an issue, and it's often outweighed by this serious power and flexibility that Photoshop layers offer.
- Creating, selecting, and organizing layers
- Controlling layer visibility, opacity, and stacking order
- Working with type and shape layers
- Practical uses for layer blend modes
- Adding dimension with layer effects and layer styles
- Using clipping layers to shape content
- Merging and saving layers
- Introducing 3D layers, video layers, and Smart Object layers