libpgm(3)                        UNIX System V                        libpgm(3)


NAME
      libpgm - functions to support portable graymap programs

SYNOPSIS
      #include <pgm.h>
      cc ... libpgm.a libpbm.a


DESCRIPTION
   TYPES AND CONSTANTS
      typedef ... gray;
      #define PGM_MAXMAXVAL ...
      extern gray pgm_pbmmaxval;

      Each gray should contain only the values between 0 and PGMMAXMAXVAL.
      pgmpbmmaxval is the maxval used when a PGM program reads a PBM file.
      Normally it is 1; however, for some programs, a larger value gives better
      results.

      #define PGM_FORMAT ...
      #define RPGM_FORMAT ...
      #define PGM_TYPE PGM_FORMAT
      int PGM_FORMAT_TYPE( int format )

      For distinguishing different file formats and types.

   INITIALIZATION
      void pgm_init( int* argcP, char* argv[] )

      All PGM programs must call this routine.

   MEMORY MANAGEMENT
      gray** pgm_allocarray( int cols, int rows )

      Allocate an array of grays.

      gray* pgmallocrow( int cols )

      Allocate a row of the given number of grays.

      void pgm_freearray( gray** grays, int rows )

      Free the array allocated with pgmallocarray() containing the given
      number of rows.

      void pgmfreerow( gray* grayrow )

      Free a row of grays.

   READING FILES
      void pgm_readpgminit( FILE* fp, int* colsP, int* rowsP, gray* maxvalP, int* formatP )



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libpgm(3)                        UNIX System V                        libpgm(3)


      Read the header from a PGM file, filling in the rows, cols, maxval and
      format variables.

      void pgmreadpgmrow( FILE* fp, gray* grayrow, int cols, gray maxval, int format )

      Read a row of grays into the grayrow array.  Format, cols, and maxval
      were filled in by pgmreadpgminit().

      gray** pgm_readpgm( FILE* fp, int* colsP, int* rowsP, gray* maxvalP )

      Read an entire graymap file into memory, returning the allocated array
      and filling in the rows, cols and maxval variables.  This function
      combines pgmreadpgminit(), pgmallocarray() and pgmreadpgmrow().

   WRITING FILES
      void pgm_writepgminit( FILE* fp, int cols, int rows, gray maxval, int forceplain )

      Write the header for a portable graymap file.  The forceplain flag forces
      a plain-format file to be written, as opposed to a raw-format one.

      void pgm_writepgmrow( FILE* fp, gray* grayrow, int cols, gray maxval, int forceplain )

      Write a row from a portable graymap.

      void pgm_writepgm( FILE* fp, gray** grays, int cols, int rows, gray maxval, int forceplain )

      Write the header and all data for a portable graymap.  This function
      combines pgmwritepgminit() and pgmwritepgmrow().

SEE ALSO
      libpbm(3), libppm(3), libpnm(3)

AUTHOR
      Copyright (C) 1989, 1991 by Tony Hansen and Jef Poskanzer.




















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