rick
   Sels, using for binary both rasterops and dwa.  Parsers are provided
   for a sequence of separable binary (rasterop and dwa) and grayscale
   brick morphological operations, in morphseq.c.  The main
   advantage in using the parsers is that you don't have to create
   and destroy Sels, or do any of the intermediate image bookkeeping.

   We also give composable separable brick functions for binary images,
   for both rasterop and dwa.  These decompose each of the linear
   operations into a sequenc