NAME

       libnetpbm - general introduction to the netpbm library

DESCRIPTION

       libnetpbm  is  a  C  programming  library  for reading, writing, and manipulating Netpbm images.  It also
       contains a few general graphics manipulation tools, but it  is  not  intended  to  be  a  graphics  tools
       library.   For  graphics  tools,  Netpbm  expects  you to run the Netpbm programs.  From a C program, the
       libnetpbm function pm_system() makes this easy.  However, since it creates a process and execs a program,
       this may be too heavyweight for some applications.

       To use libnetpbm services in your C program, #include the pam.h interface header  file.   For  historical
       reasons,  you  can  also  get  by in some cases with pbm.h, pgm.h, ppm.h, or pnm.h, but there's really no
       point to that anymore.

       The libnetpbm functions are divided into these categories:

       •      PBM functions.  These have names that start with pbm and work only on PBM images.

       •      PGM functions.  These have names that start with pgm and work only on PGM images.

       •      PPM functions.  These have names that start with ppm and work only on PPM images.

       •      PNM functions.  These have names that start with pnm and work on PBM, PGM, and PPM images.

       •      PAM functions.  These also have names that start with pnm and work on all the Netpbm image types.

       •      PM functions.  These are utility functions that aren't specific to any particular image format.

       For new programming, you rarely need to concern yourself with the  PBM,  PGM,  PPM,  and  PNM  functions,
       because  the  newer PAM functions do the same thing and are easier to use.  For certain processing of bi-
       level images, the PBM functions are significantly more efficient, though.

       libnetpbm has a backward compatibility feature that means a function designed to read one format can read
       some others too, converting on the fly.  In particular, a function that reads a PGM image will also  read
       a  PBM  image,  but  converts  it  as  it  reads  it so that for programming purposes, it is a PGM image.
       Similarly, a function that reads PPM can read PBM and PGM as well.  And a function that reads  PBM,  PGM,
       or PPM can read a PAM that has an equivalent tuple type.

       For  each  of  the  five  classes  of  libnetpbm  image  processing functions, libnetpbm has in in-memory
       representation for a pixel, a row, and a whole image.  Do not confuse this format with the  actual  image
       format,  as you would see in a file.  The libnetpbm in-memory format is designed to make programming very
       easy.  It is sometimes extremely inefficient, even more than the actual image  format.   For  example,  a
       pixel  that  a  PPM  image represents with 3 bytes, libnetpbm's PAM functions represent with 16 bytes.  A
       pixel in a PBM image is represented by a single bit, but the PNM functions represent that pixel in memory
       with 96 bits.

       See Libnetpbm User's Manual(1) for the basics on using libnetpbm in a program.

       You can look up the reference information for a particular function in The libnetpbm Directory(1).

       Before Netpbm release 10 (June 2002), this library was split  into  four:  libpbm,  libpgm,  libppm,  and
       libpnm.  That's largely the reason for the multiple sets of functions and scattered documentation.

DOCUMENT SOURCE

       This  manual  page was generated by the Netpbm tool 'makeman' from HTML source.  The master documentation
       is at

              http://netpbm.sourceforge.net/doc/libnetpbm.html

netpbm documentation                              December 2003                              Libnetpbm manual(3)