NAME

       PDL::IO::Pnm -- pnm format I/O for PDL

SYNOPSIS

         use PDL::IO::Pnm;
         $im = wpnm $pdl, $file, $format[, $raw];
         rpnm $stack->slice(':,:,:,(0)'),"PDL.ppm";

DESCRIPTION

       pnm I/O for PDL.

FUNCTIONS

   pnminraw
         Signature: (type(); byte+ [o] im(m,n); int ms => m; int ns => n;
                               int isbin; PerlIO *fp)

       Read in a raw pnm file.

       read a raw pnm file. The "type" argument is only there to determine the type of the
       operation when creating "im" or trigger the appropriate type conversion (maybe we want a
       byte+ here so that "im" follows strictly the type of "type").

       pnminraw does not process bad values.  It will set the bad-value flag of all output
       ndarrays if the flag is set for any of the input ndarrays.

   pnminascii
         Signature: (type(); byte+ [o] im(m,n); int ms => m; int ns => n;
                               int format; PerlIO *fp)

       Read in an ascii pnm file.

       pnminascii does not process bad values.  It will set the bad-value flag of all output
       ndarrays if the flag is set for any of the input ndarrays.

   pnmout
         Signature: (a(m); int israw; int isbin; PerlIO *fp)

       Write a line of pnm data.

       This function is implemented this way so that broadcasting works naturally.

       pnmout does not process bad values.  It will set the bad-value flag of all output ndarrays
       if the flag is set for any of the input ndarrays.

   rpnm
       Read a pnm (portable bitmap/pixmap, pbm/ppm) file into an ndarray.

         Usage:  $im = rpnm $file;

       Reads a file (or open file-handle) in pnm format (ascii or raw) into a pdl (magic numbers
       P1-P6).  Based on the input format it returns pdls with arrays of size (width,height) if
       binary or grey value data (pbm and pgm) or (3,width,height) if rgb data (ppm). This also
       means for a palette image that the distinction between an image and its lookup table is
       lost which can be a problem in cases (but can hardly be avoided when using
       netpbm/pbmplus).  Datatype is dependent on the maximum grey/color-component value (for raw
       and binary formats always PDL_B). rpnm tries to read chopped files by zero padding the
       missing data (well it currently doesn't, it barfs; I'll probably fix it when it becomes a
       problem for me ;). You can also read directly into an existing pdl that has to have the
       right size(!). This can come in handy when you want to read a sequence of images into a
       datacube.

       For details about the formats see appropriate manpages that come with the netpbm/pbmplus
       packages.

         $stack = zeroes(byte,3,500,300,4);
         rpnm $stack->slice(':,:,:,(0)'),"PDL.ppm";

       reads an rgb image (that had better be of size (500,300)) into the first plane of a 3D RGB
       datacube (=4D pdl datacube). You can also do inplace transpose/inversion that way.

   wpnm
       Write a pnm (portable bitmap/pixmap, pbm/ppm) file into a file or open file-handle.

         Usage:  $im = wpnm $pdl, $file, $format[, $raw];

       Writes data in a pdl into pnm format (ascii or raw) (magic numbers P1-P6).  The $format is
       required (normally produced by wpic) and routine just checks if data is compatible with
       that format. All conversions should already have been done. If possible, usage of wpic is
       preferred. Currently RAW format is chosen if compliant with range of input data. Explicit
       control of ASCII/RAW is possible through the optional $raw argument. If RAW is set to zero
       it will enforce ASCII mode. Enforcing RAW is somewhat meaningless as the routine will
       always try to write RAW format if the data range allows (but maybe it should reduce to a
       RAW supported type when RAW == 'RAW'?). For details about the formats consult appropriate
       manpages that come with the netpbm/pbmplus packages.

BUGS

       "rpnm" currently relies on the fact that the header is separated from the image data by a
       newline. This is not required by the p[bgp]m formats (in fact any whitespace is allowed)
       but most of the pnm writers seem to comply with that. Truncated files are currently
       treated ungracefully ("rpnm" just barfs).

AUTHOR

       Copyright (C) 1996,1997 Christian Soeller <c.soeller@auckland.ac.nz> All rights reserved.
       There is no warranty. You are allowed to redistribute this software / documentation under
       certain conditions. For details, see the file COPYING in the PDL distribution. If this
       file is separated from the PDL distribution, the copyright notice should be included in
       the file.