NAME

       libpbm - libnetpbm functions to read and write PBM image files

SYNOPSIS

       #include <netpbm/pbm.h>

       bit **pbm_allocarray(int cols,  int rows);

       bit *pbm_allocrow(int cols);

       pbm_freearray(bit **bits, int rows);

       pbm_freerow(bit *bitrow);

       void pbm_readpbminit(FILE * fp, int *colsP, int *rowsP, int *formatP);

       void pbm_readpbmrow(FILE * fp, bit *bitrow, int cols, int format);

       void  pbm_readpbmrow_packed(FILE  * fp, unsigned char * const packed_bits, const int cols,
       const int format);

       void bit** pbm_readpbm(FILE * fp, int *colsP, int *rowsP);

       void pbm_writepbminit(FILE * fp, int cols, int rows, int forceplain);

       void pbm_writepbmrow(FILE * fp, bit *bitrow, int cols, int forceplain);

       void pbm_writepbmrow_packed(FILE * fp, unsigned char * const packed_bits, const int  cols,
       const int forceplain);

       void pbm_writepbm(FILE * fp, bit **bits, int cols, int rows, int forceplain);

       #define pbm_packed_bytes(cols) ...

       void pbm_nextimage( FILE *file, int * const eofP);

       void  pbm_check( FILE * file, const enum pm_check_type check_type, const int format, const
       int cols, const int rows, enum pm_check_code * const retval);

DESCRIPTION

       These library functions are part of Netpbm(1).

   TYPES AND CONSTANTS
       typedef ... bit;

       #define PBM_WHITE ...

       #define PBM_BLACK ...

       Each bit should contain only the values of PBM_WHITE or PBM_BLACK.

       #define PBM_FORMAT ...

       #define RPBM_FORMAT ...

       #define PBM_TYPE PBM_FORMAT

       #define PBM_FORMAT_TYPE(f) ...

       These are for distinguishing different file formats and types.

   INITIALIZATION
       pbm_init() is obsolete (at least since  Netpbm  9.25  (March  2002)).   Use  pm_proginit()
       ⟨libpm.html#initialization⟩  instead.

       pbm_init() is identical to pm_proginit.

   MEMORY MANAGEMENT
       pbm_allocarray()  allocates an array of bits.  pbm_allocrow() allocates a row of the given
       number  of  bits.   pbm_freearray()  frees  the  array  allocated  with   pbm_allocarray()
       containing the given number of rows.  pbm_freerow() frees a row of bits.

   READING PBM IMAGE FILES
       pbm_readpbminit()  reads  the  header from a PBM image in a PBM file, filling in the rows,
       cols and format variables.  pbm_readpbmrow() reads a row of bits into  the  bitrow  array.
       Format and cols were filled in by pbm_readpbminit().

       pbm_readpbmrow_packed() is like pbm_readpbmrow() except instead of returning a bits array,
       it returns an array packed_bits of bytes with the pixels of  the  image  row  packed  into
       them.  The pixels are in order from left to right across the row and from the beginning of
       the array to the end.  Within a byte, the bits are in order from the most significant  bit
       to  the least significant bit.  If the number of pixels in the row is not a multiple of 8,
       the last byte returned is padded on the least significant bit side  with  undefined  bits.
       White is represented by a PBM_WHITE bit; black by PBM_BLACK.

       pbm_readpbm()  reads  an entire bitmap file into memory, returning the allocated array and
       filling in the  rows  and  cols  variables.   This  function  combines  pbm_readpbminit(),
       pbm_allocarray() and pbm_readpbmrow().

       pbm_readpbminit()  and  pbm_readpbm  abort the program with a message to Standard Error if
       the PBM image header is not syntactically valid, including if it  contains  a  number  too
       large  to  be  processed  using the system's normal data structures (to wit, a number that
       won't fit in a C 'int').

       ppm_readppminit() and ppm_readppm abort the program with a message to  Standard  Error  if
       the  PPM  image  header  is not syntactically valid, including if it contains a number too
       large to be processed using the system's normal data structures (to  wit,  a  number  that
       won't fit in a C 'int').

   WRITING PBM IMAGE FILES
       pbm_writepbminit()  writes  the  header  for  a  PBM image in a PBM file.  forceplain is a
       boolean value specifying that a plain format (text) file to be written, as  opposed  to  a
       raw   format   (binary)   one.    pbm_writepbmrow()   writes   a   row   to  a  PBM  file.
       pbm_writepbmrow_packed() is the same as pbm_writepbmrow() except that you supply  the  row
       to  write as an array of bytes packed with bits instead of as a bits array.  The format of
       packed_bits  is the same as that returned by pbm_readpbmrow().

       pbm_writepbm() writes the header and all data for  a  PBM  image  to  a  PBM  file.   This
       function combines pbm_writepbminit() and pbm_writepbmrow().

   MISCELLANEOUS
       pbm_nextimage()  positions  a PBM input file to the next image in it (so that a subsequent
       pbm_readpbminit() reads its header).

       Immediately before a call to pbm_nextimage(), the file must be positioned  either  at  its
       beginning  (i.e.  nothing has been read from the file yet) or just after an image (i.e. as
       left by a pbm_readpbmrow()  of the last row in the image).

       Note that in the raw PNM and PAM format, the next image always  starts  immediately  after
       the  previous  image,  so  all pbm_nextimage() really does is test whether there is a next
       image or the file is positioned at end-of-file.  In plain PNM, though, there may be  white
       space between images.

       If  pbm_nextimage()  successfully positions to the next image, it returns *eofP false (0).
       If there is no next image in the file, it returns *eofP true .  If it  can't  position  or
       determine   the   file   status   because   of   a   file   error,   it  throws  an  error
       ⟨liberror.html#error⟩ .

       pbm_check() checks for the common file integrity error where the file is the wrong size to
       contain  all  the  image  data.  pbm_check() assumes the file is positioned after an image
       header (as if pbm_readpbminit()  was the last operation on the file).  It checks the  file
       size to see if the number of bytes left in the file are the number required to contain the
       image raster.  If the file is too short, pbm_check() causes the program t throws an  error
       ⟨liberror.html#error⟩  .   Otherwise, it returns one of the following values (enumerations
       of the enum pm_check_code type) as *retval:

       PM_CHECK_OK
              The file's size is exactly what is required to hold the image raster.

       PM_CHECK_UNKNOWN_TYPE
              format is not a format whose size pbm_check() can anticipate.  The only format with
              which pbm_check() can deal is raw PBM format.

       PM_CHECK_TOO_LONG
              The file is longer than it needs to be to contain the image raster.  The extra data
              might be another image.

       PM_CHECK_UNCHECKABLE
              The file is not a kind that has a predictable size, so there is no simple  way  for
              pbm_check()  to  know if it is the right size.  Only a regular file has predictable
              size.  A pipe is a common example of a file that does not.

       check_type must have the value PM_CHECK_BASIC  (an enumerated value of  the  pm_check_type
       enumerated  type).   Otherwise, the effect of pbm_check() is unpredictable.  This argument
       exists for future backward compatible expansion of the function of pbm_check().

SEE ALSO

       libpgm(1), libppm(1), libpnm(1), pbm(1)

AUTHOR

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

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/libpbm.html