Live Transparency Effects

Opacity, masks, and blending modes are only a few of the transparency effects you can create. All three applications have special effects that can add transparency features to the image. Most of these effects are live. A live effect means that you can come back to the image and change the appearance of the effect. However, Photoshop does have one transparency effect, feathering, that is not a live effect. We'll look at each of these special effects as well as which of the applications gives you the most choices when working with the special transparency effects.

Drop Shadows

The only effect that Photoshop, Illustrator, and InDesign all share is the drop-shadow effect. However, there are substantial differences in the controls for drop shadows among the three programs.

Figure 11-11 shows the dialog boxes for creating drop shadows in Photoshop, Illustrator, and InDesign. The following is a description and comparison of their controls for drop shadows:

• Blending modes. Since Photoshop has more blending modes than Illustrator or InDesign, it stands to reason that the drop shadows in Photoshop also have more blend mode options.

• Color. Although we see shadows as dark gray things that mix with the color of the object they pass over, you can set drop shadows to be any color you wish. The major difference in the color controls is that Illustrator lets you choose a Darkness setting for the shadow. With Darkness chosen it means that a blue object will cast a blue shadow. Finally, both Illustrator and InDesign allow you to set drop shadows as spot colors. These spot-color shadows will separate correctly as long as you use the proper blend mode to maintain the transparency. (See "Spot Colors" in Chapter 10, "Colors and Color Management," for more information on how to use spot colors.)

• Opacity. All three applications have similar controls for opacity.

• Distance and Position. Photoshop allows you to position the drop shadow using an Angle field and Distance slider. The Distance slider is always measured in pixels. This means that the a drop shadow that is 30 pixels away from the image will be much closer to the artwork in a high-resolution file than a low-resolution version. Illustrator and InDesign measure the X and Y Offsets of the shadow in whatever the unit of measurement for the document. This is a resolution-independent setting.

• Angle. Photoshop has an angle setting that the other two programs don't have. Instead of changing the X and Y coordinates, you can change the angle for the shadow. This changes the position without entering new coordinates. Photoshop also has a Global Light option, which automatically coordinates all the effects that simulate light falling on the artwork. This helps keep a consistent appearance for multiple effects.

• Spread. The spread of the shadow is the size of the area that the shadow is allowed to fill. Increasing the spread creates a larger area for the shadow. Illustrator does not have a Spread control.

• Size. The size of the shadow is the width of the edge of the shadow. In Illustrator and InDesign, this setting is called Blur.

• Noise. This settings is applied to reduce the chances that as the shadow fades, the colors in the fade will band. Photoshop and InDesign have Noise controls. Illustrator does not.

Figure 11-11. Drop-shadow controls in Photoshop (left), Illustrator (top right), and InDesign (bottom right).

We have discovered an interesting difference in how drop shadows behave on objects that also have a blending mode applied. Consider a 100% magenta image set to Overlay over a 100% yellow object. All three applications treat the area where the two colors meet in the same way the magenta color disappears where it covers the yellow area. However, as shown in Figure 11-12, there is a difference in where the drop shadow appears.

Figure 11-12. Drop shadows set to Multiply, applied to artwork set to Overlay. Notice how the drop shadow in Photoshop (left) casts a shadow on the image below, while Illustrator (top right) and InDesign (bottom right) do not.

The drop shadow has been set for Multiply in all three applications. In Photoshop, the drop shadow appears all around the magenta object. The drop shadow is treated as a separate effect from the Overlay blending mode. But Illustrator and InDesign apply the drop shadow to the magenta object as if the drop shadow itself was also set to the same Overlay setting.

This is due to how each application applies the effects. Photoshop looks at the blending modes first, and then applies the drop shadow. Illustrator and InDesign apply the drop shadow objects first, and then apply the blend effect. We can't say which way is correct, but it is a difference that you should be aware of.

Inner Shadows

An inner shadow is a drop shadow applied to the inside contours of an image. The inner shadow makes it appear that the image has punched a hole in the background of the art. Only Photoshop has a setting to automatically create inner shadows (Figure 11-13). (You can simulate the effect in Illustrator or InDesign, but it's not easy and requires a lot of work to make changes.)

Figure 11-13. Controls for the Inner shadow layer effect in Photoshop.

Glows

Both Photoshop and Illustrator have settings that create glows (Figure 11-14). An outer glow spreads outside the layer or object. An inner glow is contained within the layer or object. The settings for glows are very similar to the ones for drop shadows. Inner glows can be set to start at the outside edge of the object and then move towards the center, or start at the center of the document and move towards the edge.

Figure 11-14. Outer Glow controls in Photoshop (top left) and Illustrator (bottom left). Inner Glow controls in Photoshop (top right) and Illustrator (bottom right).

Other Effects in Photoshop

Photoshop has other layer effects that can be considered part of the transparency effects:

• Bevel And Emboss allows you to add three-dimensional edges to artwork.

• Satin applies an overlay to the inside of an object that gives it a shiny appearance.

• Color, Gradient, or Pattern overlays fill the layer with solid colors, gradients, or patterns.

• Stroke adds a stroke around the edge of the artwork.

Feathers

It's ironic that Photoshop, which introduced the command Feather to soften the edges of selections, doesn't have a Feather transparency effect like the one in Illustrator and InDesign. In those two programs, feather effects can be applied and modified at any time using the Feather dialog box (Figure 11-15).

Figure 11-15. Feather controls in Illustrator (left) and InDesign (right).

We were surprised (but pleased) to see that InDesign has the most sophisticated feather controls. Not only can you adjust the width of the feathering effect, but you can choose a setting for how corner points are treated, as well as add noise to help break up any banding in the feather. These extra controls in InDesign make it our application-of-choice for applying feather effects.

Resolution for Raster Effects

When you apply effects such as shadows, glows, and feathers, you automatically add raster images to the artwork. In Photoshop, those raster images are the same as the resolution of the document. But what controls the resolution of the raster images in Illustrator or InDesign?

In Illustrator, the resolution is set in Effects > Document Raster Effects Settings. In InDesign, the resolution comes from the Flattener settings. See Chapter 16, "Preflighting and Printing" for more details on working with the Flattener settings.