When working with selections, you will often want to smooth or soften the edges of your selection before copying and pasting it into another image or layer. Anti-aliasing smoothes out the jagged edges of a selection by creating a gradual color transition along the edge (Figure 4.62). You will generally want to leave the Anti-aliased option on to leave nice smooth edges on your selections. This is especially true if you are creating a composite (combination) image by copying and pasting selections from a number of photos.
Figure 4.62. Anti-aliasing automatically smoothes a selection edge by adding pixels that blend the color transition.
Feathering blurs the edges of a selection. You set the amount of blurring on the options bar in the Feather box. Unlike anti-aliasing, which affects just the very edge of a selection, feathering creates a more dramatic, soft transition or halo effect around an image. Depending on the image selection, you may want to experiment with different feathering settings, because some detail is usually lost around the edges of a feathered selection.
To smooth jagged edges with anti-aliasing
From the toolbar, choose any selection tool other than the Rectangular Marquee tool.
The Rectangular Marquee tool's edges are composed of straight right angles, so no anti-aliasing is necessary. A rectangle selection's edge can still be softened with the Feather option.
Select Anti-alias on the options bar.
You must have anti-aliasing active before making your selection.
Make a selection using the desired tool.
Cut or copy and then paste the selection into a new file.
The resulting selection edge is auto matically smoothed, with no jaggies (Figure 4.63).
Figure 4.63. Select Anti-aliased on the options bar before you make a selection to create a smooth edge, even on curved shapes.
To feather the edge of a selection
From the toolbar, choose from any of the Marquee or Lasso tools.
On the options bar, enter a value for the feather radius (from 1 to 250 pixels).
Make a selection.
The resulting edge appears blurred, based on the number you entered for the Feather option (Figure 4.64).
Figure 4.64. To get the vignette effect shown here, use the Elliptical Marquee tool to create a border. Choose Select Feather, and enter a radius of around 10 pixels, then choose Select > Inverse to select the background. With white selected as the background color in the toolbox, press Ctrl+Backspace to complete the effect.
Unlike with anti-aliasing, you can apply feathering after you make a selection. With your selection active, from the Select menu choose Feather (Alt+Ctrl+D), then enter a feather radius.
You can also apply feathering effects to your image by applying the Vignette effect, available in the Effects palette. For more detail, see "To apply effects" in Chapter 7, "Filters and Effects."