Soften the Edges of a layer using Photoshop CS
When you combine two images, touch up an area, or apply a filter, you often want a soft transition. The Feather command softens or blurs the edge of a selection, making changes you apply blend in more naturally with its surroundings. Feathering is centered on the selection edge and blurs both in and out from the boundary. You control the width of the feathering by setting its radius value in pixels.
1. If anything is currently selected, choose Select > Deselect.
2. In the Layers palette, select the desired layer or layer set.
3. Using a selection tool, select an area in the image.
4. Choose Select > Feather.
5. Type a value for Feather Radius, and click OK. For a very subtle softening, you can type a value less than one pixel (for example, .5). The larger the value, the larger the feathered or blurred transition.
6. Apply a filter, or move, cut, copy, paint, or fill the selection. Photoshop feathers the edge.