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       pbm_init() is obsolete (at least since Netpbm 9.25 (March 2002)).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()  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 .

       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 .  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

netpbm documentation                            08 September 2007           User manual for old pbm functions(3)