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¶
rpnm¶
Read a pnm (portable bitmap/pixmap, pbm/ppm) file into a piddle.
Usage: $im = rpnm $file;
Reads a file 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.
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¶
The stderr of the converters is redirected to a file. The filename is currently
generated in a probably non-portable way. A method that avoids a file (and is
portable) would be prefered.
"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.
FUNCTIONS¶
pnminraw¶
Signature: (type(); byte+ [o] im(m,n); int ms => m; int ns => n;
int isbin; char* fd)
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 piddles if the flag is set for any of the input piddles.
pnminascii¶
Signature: (type(); byte+ [o] im(m,n); int ms => m; int ns => n;
int format; char* fd)
Read in an ascii pnm file.
pnminascii does not process bad values. It will set the bad-value flag of all
output piddles if the flag is set for any of the input piddles.
pnmout¶
Signature: (a(m); int israw; int isbin; char *fd)
Write a line of pnm data.
This function is implemented this way so that threading works naturally.
pnmout does not process bad values. It will set the bad-value flag of all output
piddles if the flag is set for any of the input piddles.