Posted by
Harry Parker on
Jan 09, 2007; 3:12pm
URL: http://imagej.273.s1.nabble.com/Fixes-to-PNM-PGM-reader-writer-tp3700640p3700641.html
Your email is a good example of why Wikipedia is a good p
Hello Dscho,
Your email is a good example of why Wikipedia is a good place to start searching, but a bad place to end your search. The Wikipedia article does link to the the reference information and software on the PNM formats at the netpbm site hosted on SourceForge. There, at
http://netpbm.sourceforge.net/doc/ppm.html , it is written, "A PPM file consists of a sequence of one or more PPM images." The original pbm format & software (from the 1980's?) may have supported only one image per file, but the PNM formats and Netpbm package have supported multiple images for years now.
A good overview link to the netpbm software is,
http://netpbm.sourceforge.net/doc/index.html.
The home page,
http://netpbm.sourceforge.net, links to versions of the software for all operating systems.
As the Netpbm site says, these uncompressed image formats are very inefficient, and have no way of including information about the images. But they are the easiest format to read and write, being a "lowest common denominator" of image files. I don't recommended them as an archive format.
--
Harry Parker
Senior Systems Engineer
Dialog Imaging Systems, Inc.
P.S.: Sending diffs is obsolete. It is a lousy way to publish software to users. Diffs do not work unless you have the exact same old version. If you want to see differences, do it yourself. That is the only way you really know that the difference between new software and YOUR source code is accurate. (If you want to see differences in context, I recommend using Kdiff3 for Windows or Linux,
http://kdiff3.sourceforge.net/.)
----- Original Message ----
From: Johannes Schindelin <
[hidden email]>
To:
[hidden email]
Sent: Tuesday, January 9, 2007 6:39:07 AM
Subject: Re: Fixes to PNM/PGM/... reader/writer
Hi,
On Thu, 4 Jan 2007, Spencer Eugene Olson wrote:
> I've added stack support to the PNM/PGM/... reader/writer. For the
> NETPBM format, stacks are simply stored as one fully formatted image
> (header and all) concatenated right after the other in the same file.
> I use the PGM format quite often and hate having hundreds of files
> hanging around which are really only slices in stacks of data.
According to
http://en.wikipedia.org/wiki/Portable_Pixmap_file_formatstacks are not part of the format. Which programs (apart from "cat") do
write such stacks?
Ciao,
Dscho
P.S.: I don't know about others, but IMHO changes to source code should be
posted as diffs, rather than complete files. It makes it easier to see
what actually changed (and there were more changes than just those
enclosed in BEGIN/END CHANGES blocks).
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