By default,
pnmtotiff
creates a TIFF file with packbits compression.
This is your best bet most of the time.
However, some TIFF readers can't deal with it.
If you want to try another compression scheme or tweak some of the
other even more obscure output options, there are a number of
flags to play with.
The
-none ,
-packbits ,
-lzw ,
-g3 ,
and
-g4
options are used to override the default and set the compression
scheme used in creating the output file. The CCITT Group 3 and Group
4 compression algorithms can only be used with bilevel data. The
-2d
and
-fill
options are meaningful only with Group 3 compression:
-2d
requests 2-dimensional encoding, while
-fill
requests that each encoded scanline be zero-filled to a byte boundry.
The
-predictor
option is only meaningful with LZW compression: a predictor value of 2
causes each scanline of the output image to undergo horizontal
differencing before it is encoded; a value of 1 forces each scanline
to be encoded without differencing.
By default,
pnmtotiff
creates a TIFF file with msb-to-lsb fill order.
The
-msb2lsb
and
-lsb2msb
options are used to override the default and set the fill order used
in creating the file.
The
-rowsperstrip
option can be used to set the number of rows (scanlines) in each
strip of data in the output file. By default, the output file has
the number of rows per strip set to a value that will ensure each
strip is no more than 8 kilobytes long.
The
-X ,
-Y ,
and
-R
options can be used to specify the X, Y, or both resolutions of the
input anymap, in pixels per inch.
