July 21, 2011, 6 p.m.
posted by lordnikon
You may have noticed two little text boxes at the top of the Layers palette labeled Opacity and Fill, as shown in Figure.
The Opacity and Fill text boxes both affect a layer’s opacity, but in different ways. The Opacity setting affects the entire layer. Every pixel on the layer is altered when the Opacity setting is changed. The Fill setting changes the opacity of the entire layer except areas where layer styles are applied. Take a look at Figure to see what I mean.
Figure: With layer styles applied to the quilt pieces, the Fill slider doesn’t change the opacity of the layer effects (bottom).
In Figure, I used layer styles to add a drop shadow and bevel to a quilt piece (top). Then, I lowered Opacity to 40% and left the Fill at 100% (middle). Notice how both the quilt piece and layer styles are semi-transparent. Next, I raised the Opacity back to 100% and lowered the Fill to 40% (bottom). As you can see, the quilt piece becomes semi-transparent, but the layer styles remain unchanged.
You can adjust layer styles opacity settings in the Layer Styles dialog box.
Depending on the effect that you want to create, you can use the Opacity setting to blend layers together in different ways. The Fill setting can be used to fade the layer contents, emphasizing the effect of the layer styles. You can even set the Fill to 0% and make the layer transparent, leaving only the layer styles effect. (See Figure.)
If you want to play around with the Opacity and Fill sliders, apply a layer style such as a drop shadow or bevel to two different layers. Then, lower the Opacity of one layer, and lower the Fill setting for the other layer. The results quickly become apparent. (Turn to Technique 20 for directions on applying layer styles.)
If you want to create a gradual fade-in/fade-out effect on a single layer, you must use a layer mask. Turn to Technique 50 for details.