Blur edges by feathering
Feathering blurs the edges of a pixel selection
and helps to blend the selected area with the surrounding pixels.
Feathering is useful when you copy a selection and paste it onto
another background.
To feather as you make a pixel selection, select a bitmap
selection tool and select Feather from the Edge pop-up menu in the
Property inspector. Drag the slider to the number of pixels you
want to blur along the edge, and then make a selection.
To feather from the menu bar, choose Select >
Feather and type a feather radius value in the Feather Selection
dialog box.
The radius value determines the number of pixels
that are feathered on each side of the selection border.
PDF (adobe.com)
