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Opacity and Fill

The Opacity value permits you to mix the active layer with the layers beneath it in prescribed portions. By way of example, consider Figure 13-3. The first image shows one of my favorite postage stamps, in which patriot and statesman Paul Revere looks for all the world like Betsy Ross. Although quite thoroughly emasculated, he is shown at full opacity, 100 percent. In the second example, I have reduced his Opacity setting to 20 percent, thereby transforming him from Paul Revere in drag to the ghost of Paul Revere in drag.

Figure 13-3: Paul Revere at 100-percent Opacity (left) and faded into the background (right).

The result is a lot like mixing a drink. Suppose you pour one part vermouth and four parts gin into a martini glass. (Any martini enthusiast knows that's too much vermouth, but bear with me on this one.) The resulting beverage is 1/5 vermouth and 4/5 gin. If the vermouth were a layer, you could achieve the same effect by setting the Opacity to 20 percent, as I did with Paul Revere. So in the case of the right half of Figure 13-3, 20 percent of what you see is Revere and the remaining 80 percent is background.

The option directly below Opacity in the Layers palette is Fill, which controls the fill opacity of a layer. Where Opacity controls the translucency of everything associated with a layer, Fill adjusts the opacity of only the filled areas. Now at first blush, there might not seem to be any difference. In Figure 13-4, for example, changing either the Opacity or Fill setting of the stamp layer to 50 percent produces the same effect: The layer is half visible and half invisible.

Figure 13-4: Whether you change the Opacity value to 50 percent (left) or the Fill value to 50 percent (right), Paul Revere looks the same.

Things change, however, if you add one or more layer effects. In Chapter 14.) Now the difference between Opacity and Fill becomes apparent — Opacity affects pixels and layer effects alike; Fill affects pixels and leaves effects unchanged.

Figure 13-5: But add a layer effect or two, and the difference between Opacity and Fill becomes obvious. Opacity makes layer and effects translucent (left), Fill alters the layer independently of its effects (right).

Fill is also more absolute than Opacity. You can lower the Opacity value to 1 percent, just shy of altogether transparent. But Photoshop lets you take Fill all the way down to 0 percent. Why? Because that allows you to reduce the fill of a layer to nothing while leaving the effects intact. Figure 13-6 shows the results of lowering the Fill value to first 20 and then 0 percent.

Figure 13-6: Using the Fill value, you can subordinate a layer to its effect (left) or fade the layer away entirely (right).

Hankering to change the Fill just as easily? Then press the Shift key. Shift-1 changes the Fill value to 10 percent, Shift-0 makes it 100 percent. Shift plus two numbers enters a two-digit value.

You also can change the setting by dragging the Opacity or Fill slider in the Layers palette (labeled back in Figure 13-2). Click the arrowhead to the right of the option to display the slider bar and then drag the triangle to change the value. Or press the up and down arrows to nudge the triangle along; press Shift with the arrow key to nudge the value in 10-percent increments. Press Enter or Return to confirm the slider setting, or press Escape to restore the previous setting.