ppmtogif - replaced by pamtogif
This program is part of
Netpbm(1).
ppmtogif was replaced in Netpbm 10.37 (December 2006) by
pamtogif(1).
pamtogif is mostly backward compatible with
ppmtogif.
One way
pamtogif is not backward compatible with
ppmtogif is that
to specify a transparency (alpha) mask with
ppmtogif, you supply the
transparency as a separate pseudo-PGM image and use the
-alpha option,
whereas with
pamtogif, you supply an input image that has the
transparency integrated into it, and there is no
-alpha option.
ppmtogif still exists as a separate program for backward compatibility,
but it runs
pamtogif to do the essential work. The compatibility
ppmtogif interprets an
-alpha option by reading the transparency
image and combining it with the input image, then feeding
pamtogif the
combined image it expects. Other than that, the compatibility
ppmtogif
just passes input and options directly to
pamtogif.
You should not make any new use of
ppmtogif and if you modify an existing
use, you should upgrade to
pamtogif. But note that if you write a
program that might have to be used with old Netpbm,
ppmtogif is the
only way to do that.
Unless you use the
-alpha option, you can simply change the name of the
program. If you use
-alpha, here is how to upgrade:
$ ppmtogif -alpha=myalpha.pgm myinput.ppm >myoutput.gif
becomes
$ pamstack -tupletype=RGB_ALPHA myinput.ppm myalpha.pgm | \
pamtogif >myoutput.gif
If you are using Netpbm before 10.37,
pamtogif doesn't exist, so you use
ppmtogif. You can use the
pamtogif manual for
ppmtogif,
with the following exceptions.
The current documentation of
pamtogif documents all versions of that
program. Use the information for Version 10.37 only.
ppmtogif before Netpbm 10.31 does not accept PAM input at all.
ppmtogif does not accept PAM input with transparency information in it.
Instead,
ppmtogif has an
-alpha option.
The syntax of the option is
-alpha=pgmfile.
ppmtogif treats
the contents of the named PGM file the same as
pamtogif treats the
alpha plane of a PAM. The PGM image must have the same dimensions as the input
file. But unlike the PAM case, the alpha image need not have the same maxval
as the input.
ppmtogif interprets the alpha file using the alpha file's
maxval.
You cannot specify both
-transparent and
-alpha.
This manual page was generated by the Netpbm tool 'makeman' from HTML source.
The master documentation is at
- http://netpbm.sourceforge.net/doc/ppmtogif.html