Layers and Effects

Trying to imagine what Photoshop would be like without layers is like trying to imagine what a peanut-butter-and-jelly sandwich is like without the bread (everything is just one gooey, sticky mess).

Imagine painting in the traditional method. As you use the brush on the canvas, you're adding paint. If you decide to paint a white cloud over a blue sky, the white paint covers the blue paint under it (some paint might show through, and we'll get to the subject of opacity soon). Theoretically, if you wanted to move that cloud to a different part of the sky, you'd have to cut it out and then glue it elsewhere, leaving a gaping hole in your canvas. It's no different in Photoshop. Let's say you create a blue sky and then draw a white cloud over a part of it. If you try to select and move that cloud elsewhere, you'll have a hole cut out of the sky where the cloud was originally (see Figure 5.39).

Figure 5.39. Moving pixels leaves a gaping hole behind.

Now let's talk about layers. Going back to the canvas, imagine that you first painted the sky and then covered your painting with a clear sheet of acetate (plastic). You then painted the white cloud on the acetate. Think about it: You'd see the same composite result, but if you moved the acetate around, you'd be able to position the cloud independently of the sky under it (see Figure 5.40). In Photoshop, think of a layer as a sheet of acetateonly better. Layers can have opacity values, blend modes, and even special effects such as drop shadows and bevels. As you'll see, Photoshop uses layers extensively to make files editable and easier to work with.

Figure 5.40. Using layers, you can reposition pixels easily.

Layers 101

Let's start with the basics. Layers are controlled via the Layers palette. Every Photoshop file starts with one layer, called a Background layer, which can be only the bottom-most layer in the document (see Figure 5.41). This layer does not support any kind of transparency.

Figure 5.41. The Background layer of a file.

To convert the Background layer so that it acts like any other layer, double-click on it to rename it Layer 0 and click OK.

To add a layer to a file, click on the Create New Layer button in the Layers palette. Alternatively, you can drag an existing layer on top of the Create New Layer icon to create a duplicate layer. You can drag layers up and down to shuffle them within the hierarchy of the Layers palette. Layers at the bottom of the palette are stacked behind those that appear at the top of the palette (see Figure 5.42).

Figure 5.42. The same image with different layer hierarchies, demonstrating how layer order affects the stacking order of objects in the document.

Viewing and Locking Layers

Besides being able to shuffle the stacking order of objects by moving layers up and down in the Layers palette, you can choose to show or hide any layer at any time. The little eye icon to the far left of each layer indicates whether a layer is visible (see Figure 5.43). Click once on the eye to hide the layer; click again to show the layer. If you Option+click (Alt+click) an eye, Photoshop automatically hides all the other layers in your document, enabling you to see just the layer you're working on.

Figure 5.43. The visibility icon indicates whether a layer is shown or hidden.

Using the Move tool, you can move the items on a layer, but sometimes you'll want to move several items together at onceand those items may be on different layers. Photoshop CS2 now enables you to Shift+click layers to select them so you can move them or apply transformations to them. You can Command+click (Ctrl+click) to select noncontiguous layers as well. If you are constantly moving several layers as a single unit, rather than having to select them each time, you can link them by first selecting the layers and then clicking on the Link button at the bottom left of the Layers palette. When you do so, a link icon appears on those layers, indicating that the transform edits you make will occur to those layers as a unit (see Figure 5.44). Transform edits consist of moving, scaling, and rotating, as well as using the Free Transform tool.

Figure 5.44. Several layers linked, indicating that they can be transformed together all at once.

Layer Opacity and Blend Modes

As mentioned earlier, you can apply opacity levels to a layer or blend modes that affect the appearance of the pixels on the layer. For example, changing the opacity of the top layer of your document (see Figure 5.45) enables you to "see through" that layer to the layer underneathbasically allowing the lower layer to show through. Blend modes enable you to specify how the pixels from the upper layer and those from the lower layer mix with each other. For example, if you had two layers and Layer 1 was filled with blue and Layer 2 was filled with yellow, you could set Layer 2 to use the Multiply blend mode to give you a green result.

Figure 5.45. Specifying an opacity value for a selected layer.

By the Way

With the Move tool selected in the toolbox, you can press Shift along with the plus (+) or minus () key to step through the different blend modes. This enables you to quickly see how the different blend modes will affect the image's final appearance.

Layer Sets

Managing a lot of layers can be difficult, and having to scroll through a large number of them is time-consuming as well. Similar in concept to Illustrator, Photoshop has the capability to create groups. A group is like a folder that has several layers inside it (see Figure 5.46). You can also put a group into another group (up to four levels deep), giving you even more control.

Figure 5.46. Several layers inside a group.

Create new groups by clicking on the Create a New Group button at the bottom of the Layers palette, and you can add other layers into a group by dragging them into the group (see Figure 5.47).

Figure 5.47. Dragging a layer into a group.

Layer Styles

Each layer can have several effects applied to it, which Photoshop refers to as Layer Styles. You can access the Layer Style dialog box by choosing Blending Options from the Layer palette flyout menu. Alternatively, you can double-click on the layer itself (just not on the actual name of the layer).

To apply a particular effect, check the box for it along the left side of the dialog box (see Figure 5.48). For each effect, you can use specific settings to control how that effect is applied. A layer can have any combination of these effects.

Figure 5.48. The Layer Style dialog box with the Drop Shadow options showing.

By the Way

Double-click on a layer's name in the Layers palette to edit the name of the layer. Double-click elsewhere in the layer to open the Layer Style dialog box.

Here are some of the functions you can apply in a layer style:

• Drop Shadow Probably the most overused effect ever created, the drop shadow is still very useful to make elements seem to pop off the page. This effect creates a soft shadow along the outside of the boundaries of your layer.

• Inner Shadow Creates a shadow within transparent areas on your layer. The effect causes your image to appear to be cut out of the page.

• Outer Glow Adds a glow around the perimeter of objects on the selected layer.

• Inner Glow Applies the reverse effect of the outer glow.

• Bevel and Emboss Contains several settings that make an image appear as if it were three-dimensional by adding highlighted edges. Used often for making web buttons.

• Satin Adds shadows and highlights to make the image appear as if it has the pillowed waves or ripples of satin.

• Color Overlay Simply adds a color over the entire layer. Colors can be set with an opacity, and this can be used to create color casts or special effects.

• Gradient Overlay Same as Color Overlay, but uses gradient fills.

• Pattern Overlay Same as Color Overlay and Gradient Overlay, but with pattern fills.

• Stroke Can be used to simulate a stroked outline around your layer.

Saving and Reusing Styles

When you've defined a style that you like, you can save it as a style, which you can then easily apply to other layers. After you save a style, it appears in the Styles palette (see Figure 5.49). Alternatively, you can define styles directly from the Styles palette.

Figure 5.49. Choosing a layer style from the Styles palette.

Photoshop actually ships with several sets of styles you can use. More important, you can reverse-engineer these styles by seeing how they were created. You can access these sets from the Styles palette flyout menu (see Figure 5.50).

Figure 5.50. Accessing Photoshop's predefined styles.

Layer Comps

Because layers can be manipulated so easily in Photoshop, and because they are nondestructive, designers often use layers to create different variations of a design. By hiding or showing different layers, they can quickly preview several different design ideaseither throughout their own process or to show a client several design possibilities.

Continually hiding and showing layers can be tediousespecially when you're trying to remember which layers were used for which design concept. So the wonderful folks at Adobe added a feature called layer comps, which manages this entire process quite well. Layer comps can save the visibility, position, and appearance (layer style) of each layer in your document. You can then quickly step through different layer comps to see what your designs look like. Because Photoshop is simply remembering the "state" of each layer, if you change an item on a certain layer, that change is automatically made on all of your layer comps, so it's a great time saver as well.

To create a layer comp, begin in the Layers palette and hide or show your layers as necessary to show your first design. Then open the Layer Comps palette and click on the Create New Layer Comp button. You're presented with a dialog box (see Figure 5.51), where you can name your comp, choose which attributes Photoshop will save, and add a comment (always helpful for those of us who forget easily). Where was I again? Oh, yes, you can create additional layer comps by repeating the process. To preview each of your comps, simply click on the icon along the left side of the Layer Comps palette (see Figure 5.52).

Figure 5.51. The New Layer Comp dialog box.

Figure 5.52. The icon on the left indicates which layer comp is active.

When we discuss scripting later in the chapter, you'll learn how to automatically generate multiple-page PDF files from your layer comps.

Did you Know?

You might want to get used to creating layer comps because both Illustrator CS2 and InDesign CS2 have the capability to choose between layer comps when you import the file into your layouts. That means you can create several design ideas in a Photoshop file using layer comps and then place a single file into your layout, at which time you'll be asked to choose which design idea you want to appear in your layout for that use.