r is encoded into the raw data buffer (from
where it is written).  Decoding routines should never have to explicitly
read data -- a full strip/tile's worth of raw data is read and scanlines
never cross strip boundaries.  Encoding routines must be cognizant of
the raw data buffer size and call <TT>TIFFFlushData1()</TT> when necessary.
Note that any pending data is automatically flushed when a new strip/tile is
started, so there's no need do that in the tif_postencode routine (if
one exists).  Bit order is au