In use, the most common morphological Sels are separable bricks,
of dimension n x m (where either n or m, but not both, is commonly 1).
Accordingly, we provide separable morphological operations on brick
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.