UNSHARP_MASK is a basic image enhancement routine which uses the unsharp mask method. The calling sequence is:
IDL> dataout=unsharp_mask(index, data)
where data and dataout are 2D arrays, and index is the index
entry that corresponds to data. If no keywords are given the
defaults are used.
Optional Keyword Parameters:
The keyword parameters allow you to customize the enhancer, though they are all assigned default values if omitted in the call. These defaults depend on the images resolution, and may be changed as we gain experience.