You can apply a soft edge to masks and keylines using the Filter Browser.
- Open the Filter Browser and add a new filter set by pressing the + button highlighted below. This will duplicate the filter which was selected at the time.
- Double click on the new filter to rename it to something more appropriate, like ‘Soften.’
- Edit the filters to a Gaussian Blur with appropriate strength, and choose which direction the blur effect should move in.
Note: You may have to delete some filters from the filter set, depending on what was duplicated when you created your new filter set.
- Close the Filter Browser.
- Select an appropriate Brush to use from the Brushes Palette, and from the popup menu, choose your newly created added filter.
- Begin to paint along the edges of a shape or key line to smooth the edges.
This technique can be particularly effective for cleaning up rough, 1 bit layer. In the snapshot below, the original information is on the left, and the cleaned up mask is on the right,
Note: The default setting for the Paint Brush Tool is ‘Brush”, located at the top of this drop down menu. To prevent you from becoming confused between the default setting and a filter setting, do not name any filters ‘Brush’. When you have finished painting with your filter, set the drop down menu back to the Brush setting, otherwise the Paint Brush Tool may not behave as you would expect later on.