                                     Netpbm

   Updated: 15 April 2005
   [1]Table Of Contents

Overview Of Netpbm

   Netpbm is a package of graphics programs and a programming library.

   There are over 220 separate programs in the package, most of which have
   "pbm", "pgm", "ppm", "pam", or "pnm" in their names. For example,
   [2]pamscale and [3]giftopnm.

   For example, you might use pamscale to shrink an image by 10%. Or use
   pamcomp to overlay one image on top of another. Or use pbmtext to
   create an image of text. Or reduce the number of colors in an image
   with pnmquant.

   Netpbm is an open source software package, distributed via the
   [4]Sourceforge netpbm project.

The Netpbm Programs

   The Netpbm programs are generally useful run by a person from a command
   shell, but are also designed to be used by programs. A common
   characteristic of Netpbm programs is that they are simple, fundamental
   building blocks. They are most powerful when stacked in pipelines.
   Netpbm programs do not use graphical user interfaces (in fact, none of
   them display graphics at all, except for a very simple Linux Svgalib
   displayer) and do not seek input from a user.

   Each of these programs has its own manual, as linked in the directory
   below.

   The Netpbm programs can read and write files greater than 2 GiB
   wherever the underlying system can. There may be exceptions where the
   programs use external libraries (The JPEG library, etc.) to access
   files and the external library does not have large file capability.
   Before Netpbm 10.15 (April 2003), no Netpbm program could read a file
   that large.

  Common Options

   There are a few options that are present on all programs that are based
   on the Netpbm library, including virtually all Netpbm programs. These
   are not mentioned in the individual manuals for the programs.

   You can use two hyphens instead of one on these options if you like.
   -quiet
          Suppress all informational messages that would otherwise be
          issued to Standard Error. (To be precise, this only works to the
          extent that the program in question implements the Netpbm
          convention of issuing all informational messages via the
          pm_message() service of the Netpbm library).
   -version
          Instead of doing anything else, report the version of the
          libnetpbm library linked with the program (it may have been
          linked statically into the program, or dynamically linked at run
          time). Normally, the Netpbm programs and the library are
          installed at the same time, so this tells you the version of the
          program and all the other Netpbm files it uses as well.
   -plain
          If the program generates an image in Netpbm format, generate it
          in the "plain" (aka "ascii") version of the format, as opposed
          to the "raw" (aka "binary") version.
          This option was introduced in Netpbm 10.10 (October 2002).

  Directory

   Here is a complete list of all the Netpbm programs (with links to their
   manuals):

   [5]Netpbm program directory

  How To Use The Programs

   As a collection of primitive tools, the power of Netpbm is multiplied
   by the power of all the other unix tools you can use with them. These
   notes remind you of some of the more useful ways to do this. Often,
   when people want to add high level functions to the Netpbm tools, they
   have overlooked some existing tool that, in combination with Netpbm,
   already does it.

   Often, you need to apply some conversion or edit to a whole bunch of
   files.

   As a rule, Netpbm programs take one input file and produce one output
   file, usually on Standard Output. This is for flexibility, since you so
   often have to pipeline many tools together.

   Here is an example of a shell command to convert all your of PNG files
   (named *.png) to JPEG files named *.jpg:
for i in *.png; do pngtopnm $i | ppmtojpeg >`basename $i .png`.jpg; done

   Or you might just generate a stream of individual shell commands, one
   per file, with awk or perl. Here's how to brighten 30 YUV images that
   make up one second of a movie, keeping the images in the same files:
ls *.yuv
   | perl -ne 'chomp;
   print yuvtoppm $_ | ppmbrighten -v 100 | ppmtoyuv >tmp$$.yuv;
   mv tmp$$.yuv $_
   '
   | sh

   The tools find (with the -exec option) and xargs are also useful for
   simple manipulation of groups of files.

   Some shells' "process substitution" facility can help where a
   non-Netpbm program expects you to identify a disk file for input and
   you want it to use the result of a Netpbm manipulation. Say the
   hypothetical program printcmyk takes the filename of a Tiff CMYK file
   as input and what you have is a PNG file abc.png. Try:
printcmyk <({ pngtopnm abc.png | pnmtotiffcmyk ; })

   It works in the other direction too, if you have a program that makes
   you name its output file and you want the output to go through a Netpbm
   tool.

The Netpbm Formats

   All of the programs work with a set of graphics formats called the
   "netpbm" formats. Specifically, these formats are [6]pbm, [7]pgm,
   [8]ppm, and [9]pam. The first three of these are sometimes known
   generically as "pnm". Many of the Netpbm programs convert from a Netpbm
   format to another format or vice versa. This is so you can use the
   Netpbm programs to work on graphics of any format. It is also common to
   use a combination of Netpbm programs to convert from one non-Netpbm
   format to another non-Netpbm format. Netpbm has converters for about
   100 graphics formats, and as a package Netpbm lets you do more graphics
   format conversions than any other computer graphics facility.

   The Netpbm formats are all raster formats, i.e. they describe an image
   as a matrix of rows and columns of pixels. In the PBM format, the
   pixels are black and white. In the PGM format, pixels are shades of
   gray. In the PPM format, the pixels are in full color. The PAM format
   is more sophisticated. A replacement for all three of the other
   formats, it can represent matrices of general data including but not
   limited to black and white, grayscale, and color images.

   Programs designed to work with PBM images have "pbm" in their names.
   Programs designed to work with PGM, PPM, and PAM images similarly have
   "pgm", "ppm", and "pam" in their names.

   All Netpbm programs designed to read PGM images see PBM images as if
   they were PGM too. All Netpbm programs designed to read PPM images see
   PGM and PBM images as if they were PPM. See [10]Implied Format
   Conversion.

   Programs that have "pnm" in their names read PBM, PGM, and PPM but
   unlike "ppm" programs, they distinguish between them and their function
   depends on the format. For example, [11]pnmtopng creates a black and
   white PNG output image if its input is PBM or PGM, but a color PNG
   output image if its input is PPM. And pnmrotate produces an output
   image of the same format as the input. A hypothetical ppmrotate program
   would also read all three PNM input formats, but would see them all as
   PPM and would always generate PPM output.

   Programs that have "pam" in their names read all the Netpbm formats:
   PBM, PGM, PPM, and PAM. They sometimes treat them all as if they are
   PAM, using an implied conversion, but often they recognize the
   individual formats and behave accordingly, like a "pnm" program does.
   See [12]Implied Format Conversion.

   If it seems wasteful to you to have three separate PNM formats, be
   aware that there is a historical reason for it. In the beginning, there
   were only PBMs. PGMs came later, and then PPMs. Much later came PAM,
   which realizes the possibility of having just one aggregate format.

   The formats are described in the specifications of [13]pbm, [14]pgm,
   [15]ppm, and [16]pam.

  Implied Format Conversion

   A program that uses the PGM library subroutines to read an image can
   read a PBM image as well as a PGM image. The program sees the PBM image
   as if it were the equivalent PGM image, with a maxval of 255. note:
   This sometimes confuses people who are looking at the formats at a
   lower layer than they ought to be because a zero value in a PBM raster
   means white, while a zero value in a PGM raster means black.

   A program that uses the PPM library subroutines to read an image can
   read a PGM image as well as a PPM image and a PBM image as well as a
   PGM image. The program sees the PBM or PGM image as if it were the
   equivalent PPM image, with a maxval of 255 in the PBM case and the same
   maxval as the PGM in the PGM case.

   A program that uses the PAM library subroutines to read an image can
   read a PBM, PGM, or PPM image as well as a PAM image. The program sees
   a PBM image as if it were the equivalent PAM image with tuple type
   BLACKANDWHITE. It sees a PGM image as if it were the equivalent PAM
   image with tuple type GRAYSCALE. It sees a PPM image as if it were the
   equivalent PAM image with tuple type RGB. But the program actually can
   see deeper if it wants to. It can tell exactly which format the input
   was and may respond accordingly. For example, a PAM program typically
   produces output in the same format as its input.

  Netpbm and Transparency

   In many graphics formats, there's a means of indicating that certain
   parts of the image are wholly or partially transparent, meaning that if
   it were displayed "over" another image, the other image would show
   through there. Netpbm formats deliberately omit that capability, since
   their purpose is to be extremely simple.

   In Netpbm, you handle transparency via a transparency mask in a
   separate (slightly redefined) PGM image. In this pseudo-PGM, what would
   normally be a pixel's intensity is instead an opaqueness value. See
   [17]pgm. [18]pamcomp is an example of a program that uses a PGM
   transparency mask.

   Another means of representing transparency information has recently
   developed in Netpbm, using PAM images. In spite of the argument given
   above that Netpbm formats should be too simple to have transparency
   information built in, it turns out to be extremely inconvenient to have
   to carry the transparency information around separately. This is
   primarily because Unix shells don't provide easy ways to have networks
   of pipelines. You get one input and one output from each program in a
   pipeline. So you'd like to have both the color information and the
   transparency information for an image in the same pipe at the same
   time.

   For that reason, some new (and recently renovated) Netpbm programs
   recognize and generate a PAM image with tuple type RGB_ALPHA or
   GRAYSCALE_ALPHA, which contains a plane for the transparency
   information. See [19]the PAM specification.

The Netpbm Library

   The Netpbm programming library, [20]libnetpbm, makes it easy to write
   programs that manipulate graphic images. Its main function is to read
   and write files in the Netpbm formats, and because the Netpbm package
   contains converters for all the popular graphics formats, if your
   program reads and writes the Netpbm formats, you can use it with any
   formats.

   But the library also contain some utility functions, such as character
   drawing and RGB/YCrCb conversion.

   The library has the conventional C linkage. Virtually all programs in
   the Netpbm package are based on the Netpbm library.

netpbm-config

   In a standard installation of Netpbm, there is a program named
   netpbm-config in the regular program search path. We don't consider
   this a Netpbm program -- it's just an ancillary part of a Netpbm
   installation. This program tells you information about the Netpbm
   installation, and is intended to be run by other programs that
   interface with Netpbm. In fact, netpbm-config is really a configuration
   file, like those you typically see in the /etc/ directory of a Unix
   system.

   Example:
    $netpbm-config --datadir
    /usr/local/netpbm/data

   If you write a program that needs to access a Netpbm data file, it can
   use such a shell command to find out where the Netpbm data files are.

   netpbm-config is the only file that must be installed in a standard
   directory (it must be in a directory that is in the default program
   search path). You can use netpbm-config as a bootstrap to find all the
   other Netpbm files.

   There is no detailed documentation of netpbm-config. If you're in a
   position to use it, you should have no trouble reading the file itself
   to figure out how to use it.

Companion Software

  PHP-NetPBM

   If you're using Netpbm to do graphics for a website, you can invoke the
   Netpbm programs from a PHP script. To make this even easier, check out
   [21]PHP-NetPBM, a PHP class that interacts with Netpbm. Its main goal
   is to decrease the pain of using Netpbm when working with images in
   various formats. It includes macro commands to perform manipulations on
   many files.

   I can't actually recommend PHP-NetPBM. I spent some time staring at it
   and was unable to make sense of it. Some documentation is in fractured
   English and other is in an unusual character set. But a PHP expert
   might be able to figure it out and get some use out of it.

Other Graphics Software

   Netpbm contains primitive building blocks. It certainly is not a
   complete graphics software library.

  Graphics Viewers

   The first thing you will want to make use of any of these tools is a
   viewer. (On GNU/Linux, you can use ppmsvgalib in a pinch, but it is
   pretty limiting). zgv is a good full service viewer to use on a
   GNU/Linux system with the SVGALIB graphics display driver library. You
   can find zgv at
   [22]ftp://ftp.ibiblio.org/pub/Linux/apps/graphics/viewers/svga.

   zgv even has a feature in it wherein you can visually crop an image and
   write an output file of the cropped image using [23]pamcut. See the -s
   option to zgv.

   For the X inclined, there is also xzgv.

   xloadimage and its extension xli are also common ways to display a
   graphic image in X.

   gqview is a more modern X-based image viewer.

   qiv is a small, very fast viewer for X.

   To play mpeg movies, such as produced by ppmtompeg, try [24]xine.

   See [25]ftp://metalab.unc.edu/pub/Linux/apps/graphics/viewers/X.

  Visual Graphics Software

   Visual graphics software is modern point-and-click software that
   displays an image and lets you work on it and see the results as you
   go. This is fundamentally different from what Netpbm programs do.

   ImageMagick is like a visual version of Netpbm. Using the X/Window
   system on Unix, you can do basic editing of images and lots of format
   conversions. The package does include at least some non-visual tools.
   convert, mogrify, montage, and animate are popular programs from the
   ImageMagick package. ImageMagick runs on Unix, Windows, Windows NT,
   Macintosh, and VMS.

   xv is a very old and very popular simple image editor in the Unix
   world. It does not have much in the way of current support, or
   maintenance, though.

   The Gimp is a visual image editor for Unix and X, in the same category
   as the more famous, less capable, and much more expensive Adobe
   Photoshop, etc. for Windows. See [26]http://www.gimp.org.

   Electric Eyes, kuickshow, and gthumb are also visual editors for the
   X/Window system, and KView and gwenview are specifically for KDE.

  Programming Tools

   If you're writing a program in C to draw and manipulate images, check
   out [27]gd. Netpbm contains a C library for drawing images, but it is
   probably not as capable or documented as gd. You can easily run any
   Netpbm program from a C program with the pm_system function from the
   Netpbm programming library, but that is less efficient than gd
   functions that do the same thing.

   Ilib is a C subroutine library with functions for adding text to an
   image (as you might do at a higher level with pbmtext, pamcomp, etc.).
   It works with Netpbm input and output. Find it at
   [28]http://www.radix.net/~cknudsen/Ilib. Netpbm also includes character
   drawing functions in the [29]libnetpbm library, but they do not have as
   fancy font capabilities (see [30]ppmlabel for an example of use of the
   Netpbm character drawing functions).

   GD is a library of graphics routines that is part of PHP. It has a
   subset of Netpbm's functions and has been found to resize images more
   slowly and with less quality.

  Tools For Specific Graphics Formats

   To create an animated GIF, or extract a frame from one, use gifsicle.
   gifsicle converts between animated GIF and still GIF, and you can use
   ppmtogif and giftopnm to connect up to all the Netpbm utilities. See
   [31]http://www.lcdf.org/gifsicle.

   To convert an image of text to text (optical character recongition -
   OCR), use gocr (think of it as an inverse of pbmtext). See
   [32]http://altmark.nat.uni-magdeburg.de/~jschulen/ocr/.

   [33]http://schaik.com/pngsuite contains a PNG test suite -- a whole
   bunch of PNG images exploiting the various features of the PNG format.

   Another version of Netpbm's pnmtopng/pngtopnm is at
   [34]http://www.schaik.com/png/pnmtopng.html.

   The version in Netpbm was actually based on that package a long time
   ago, and you can expect to find better exploitation of the PNG format,
   especially recent enhancements, in that package. It may be a little
   less consistent with the Netpbm project and less exploitive of recent
   Netpbm format enhancements, though.

   [35]pngwriter is a C++ library for creating PNG images. With it, you
   plot an image pixel by pixel. You can also render text with the
   FreeType2 library.

   jpegtran Does some of the same transformations as Netpbm is famous for,
   but does them specifically on JPEG files and does them without loss of
   information. By contrast, if you were to use Netpbm, you would first
   decompress the JPEG image to Netpbm format, then transform the image,
   then compress it back to JPEG format. In that recompression, you lose a
   little image information because JPEG is a lossy compression. Of
   course, only a few kinds of lossless transformation are possible.
   jpegtran comes with the Independent Jpeg Group's
   ([36]http://www.ijg.org) JPEG library.

   Some tools to deal with EXIF files (see also Netpbm's [37]jpegtopnm and
   [38]pnmtojpeg): To dump (interpret) an EXIF header: Exifdump
   (([39]http://topo.math.u-psud.fr/~bousch/exifdump.py)) or Jhead
   ([40]http://www.sentex.net/~mwandel/jhead.)

   A Python EXIF library and dumper: [41]http://pyexif.sourceforge.net.

   Here's some software to work with IOCA (Image Object Content
   Architecture): [42]ImageToolbox ($2500, demo available). This can
   convert from TIFF -> IOCA and back again. [43]Ameri-Imager ($40 Windows
   only).

   pnm2ppa converts to HP's "Winprinter" format (for HP 710, 720, 820,
   1000, etc). It is a superset of Netpbm's pbmtoppa and handles, notably,
   color. However, it is more of a printer driver than a Netpbm-style
   primitive graphics building block. See
   [44]http://sourceforge.net/project/?group_id=1322.

  Document/Graphics Software

   There is a large class of software that does document processing, and
   that is somewhat related to graphics because documents contain graphics
   and a page of a document is for many purposes a graphic image. Because
   of this slight intersection with graphics, I cover document processing
   software here briefly, but it is for the most part beyond the scope of
   this document.

   First, we look at where Netpbm meets document processing. pstopnm
   converts from Postscript and PDF to PNM. It effectively renders the
   document into images of printed pages. pstopnm is nothing but a
   convenient wrapper for [45]Ghostscript, and in particular Netpbm-format
   device drivers that are part of it. pnmtops and pbmtoepsi convert a PNM
   image to a Postscript program for printing the image. But to really use
   PDF and Postscript files, you generally need more complex document
   processing software.

   Adobe invented Postscript and PDF and products from Adobe are for many
   purposes the quintessential Postscript and PDF tools.

   Adobe's free Acrobat Reader displays PDF and converts to Postscript.
   The Acrobat Reader for unix has a program name of "acroread" and the
   -toPostScript option (also see the -level2 option) is useful.

   Other software from Adobe, available for purchase, interprets and
   creates Postscript and PDF files. "Distill" is a program that converts
   Postscript to PDF.

   [46]xpdf also reads PDF files.

   GSview, ghostview, gv, ggv, and kghostview are some other viewers for
   Postscript and PDF files.

   The program ps2pdf, part of Ghostscript, converts from Postscript to
   PDF.

   Two packages that produce more kinds of Encapsulated Postscript than
   the Netpbm programs, including compressed kinds, are [47]bmeps and
   [48]imgtops.

   dvips converts from DVI format to Postscript. DVI is the format that
   Tex produces. Netpbm can convert from Postscript to PNM. Thus, you can
   use these in combination to work with Tex/Latex documents graphically.

   [49]wvware converts a Microsoft Word document (.doc file) to various
   other formats. While the web page doesn't seem to mention it, it
   reportedly can extract an embedded image in a Word document as a PNG.

   [50]doc2png extracts an image from a Microsoft Word document too.

   Latex2html converts Latex document source to HTML document source. Part
   of that involves graphics, and Latex2html uses Netpbm tools for some of
   that. But Latex2html through its history has had some rather esoteric
   codependencies with Netpbm. Older Latex2html doesn't work with current
   Netpbm. Latex2html-99.2beta8 works, though.

  Other

   The file program looks at a file and tells you what kind of file it is.
   It recognizes most of the graphics formats with which Netpbm deals, so
   it is pretty handy for graphics work. Netpbm's [51]anytopnm program
   depends on file. See [52]ftp://ftp.astron.com/pub/file.

   The Utah Raster Toolkit serves a lot of the same purpose as Netpbm, but
   without the emphasis on format conversions. This package is based on
   the RLE format, which you can convert to and from the Netpbm formats.
   [53]http://www.cs.utah.edu/gdc/projects/urt.html gives some information
   on the Utah Raster Toolkit, but does not tell where to get it.

   Ivtools is a suite of free X Windows drawing editors for Postscript,
   Tex, and web graphics production, as well as an embeddable and
   extendable vector graphic shell. It uses the Netpbm facilities. See
   [54]http://www.ivtools.org.

   The program morph morphs one image into another. It uses Targa format
   images, but you can use tgatoppm and ppmtotga to deal with that format.
   You have to use the graphical (X/Tk) Xmorph to create the mesh files
   that you must feed to morph. morph is part of the Xmorph package. See
   [55]http://www.colorado-research.com/~gourlay/software/Graphics/Xmorph.

Other Graphics Formats

   People never seem to tire of inventing new graphics formats, often
   completely redundant with pre-existing ones. Netpbm cannot keep up with
   them. Here is a list of a few that we know Netpbm does not handle
   (yet).

   Various commercial Windows software handles dozens of formats that
   Netpbm does not, especially formats typically used with Windows
   programs. ImageMagick is probably the most used free image format
   converter and it also handles lots of formats Netpbm does not.
     * [56]VRML (Virtual Reality Modelling Language)
     * CAL (originated by US Department Of Defense, favored by
       architects).
       [57]http://www.landfield.com/faqs/graphics/fileformats-faq/part3/se
       ction-24.html
     * array formats dx, general, netcdf, CDF, hdf, cm
     * CGM+
     * Windows Meta File (.WMF). Libwmf converts from WMF to things like
       Latex, PDF, PNG. Some of these can be input to Netpbm.
     * Microsoft Word, RTF. Microsoft keeps a proprietary hold on these
       formats. Any software you see that can handle them is likely to
       cost money.
     * DXF (AutoCAD)
     * IOCA (Image Object Content Architecture) The specification of this
       format is documented by IBM: [58]Data Stream and Object
       Architectures: Image Object Content Architecture Reference. See
       above for software that processes this format.
     * SVG. Find out about this vector graphics format and software to use
       with it at [59]this Worldwide Web Consortium web page.
     * OpenEXR is an HDR format (like [60]PFM). See
       [61]http://www.openexr.org/about.html.
     * Xv Visual Schnauzer thumbnail image. This is a rather antiquated
       format used by the Xv program. In Netpbm circles, it is best known
       for the fact that it is very similar to Netpbm formats and uses the
       same signature ("P7") as PAM because it was developed as sort of a
       fork of the Netpbm format specifications.
     * YUV 4:2:0, aka YUV 420, and the simlar YUV 4:4:4, YUV 4:2:2, YUV
       4:1:1, YUV 4:1:1s, and YUV 4:1:0. Video systems often use this.



History

   Netpbm has a long history, starting with Jef Poskanzer's Pbmplus
   package in 1988. The file HISTORY in the Netpbm source code contains a
   historical overview as well as a detailed history release by release.

Author

   Netpbm is based on the Pbmplus package by Jef Poskanzer, first
   distributed in 1988 and maintained by him until 1991. But the package
   contains work by countless other authors, added since Jef's original
   work. In fact, the name is derived from the fact that the work was
   contributed by people all over the world via the Internet, when such
   collaboration was still novel enough to merit naming the package after
   it.

   Bryan Henderson has been maintaining Netpbm since 1999. In addition to
   packaging work by others, Bryan has also written a significant amount
   of new material for the package.
     __________________________________________________________________



Table Of Contents

     * [62]Overview Of Netpbm
     * [63]The Netpbm Formats
          + [64]Implied Format Conversion
          + [65]Netpbm and Transparency
     * [66]The Netpbm Programs
          + [67]Common Options
          + [68]Directory
          + [69]How To Use The Programs
     * [70]The Netpbm Library
     * [71]netpbm-config
     * [72]Companion Software
          + [73]PHP-NetPBM
     * [74]Other Graphics Software
     * [75]Other Graphics Formats
     * [76]History
     * [77]Author

References

   1. http://netpbm.sourceforge.net/doc/#index
   2. http://netpbm.sourceforge.net/doc/pamscale.html
   3. http://netpbm.sourceforge.net/doc/giftopnm.html
   4. http://sourceforge.net/projects/netpbm
   5. http://netpbm.sourceforge.net/doc/directory.html
   6. http://netpbm.sourceforge.net/doc/pbm.html
   7. http://netpbm.sourceforge.net/doc/pgm.html
   8. http://netpbm.sourceforge.net/doc/ppm.html
   9. http://netpbm.sourceforge.net/doc/pam.html
  10. http://netpbm.sourceforge.net/doc/#impconv
  11. http://netpbm.sourceforge.net/doc/pnmtopng.html
  12. http://netpbm.sourceforge.net/doc/#impconv
  13. http://netpbm.sourceforge.net/doc/pbm.html
  14. http://netpbm.sourceforge.net/doc/pgm.html
  15. http://netpbm.sourceforge.net/doc/ppm.html
  16. http://netpbm.sourceforge.net/doc/pam.html
  17. http://netpbm.sourceforge.net/doc/pgm.html
  18. http://netpbm.sourceforge.net/doc/pamcomp.html
  19. http://netpbm.sourceforge.net/doc/pam.html
  20. http://netpbm.sourceforge.net/doc/libnetpbm.html
  21. http://sourceforge.net/projects/phpnetpbm
  22. ftp://ftp.ibiblio.org/pub/Linux/apps/graphics/viewers/svga
  23. http://netpbm.sourceforge.net/doc/pamcut.html
  24. http://sourceforge.net/projects/xine
  25. ftp://metalab.unc.edu/pub/Linux/apps/graphics/viewers/X
  26. http://www.gimp.org/
  27. http://www.boutell.com/gd
  28. http://www.radix.net/~cknudsen/Ilib
  29. http://netpbm.sourceforge.net/doc/libnetpbm.html
  30. http://netpbm.sourceforge.net/doc/ppmlabel.html
  31. http://www.lcdf.org/gifsicle
  32. http://altmark.nat.uni-magdeburg.de/~jschulen/ocr/
  33. http://schaik.com/pngsuite
  34. http://www.schaik.com/png/pnmtopng.html
  35. http://pngwriter.sourceforge.net/
  36. http://www.ijg.org/
  37. http://netpbm.sourceforge.net/doc/jpegtopnm.html
  38. http://netpbm.sourceforge.net/doc/pnmtojpeg.html
  39. http://topo.math.u-psud.fr/~bousch/exifdump.py
  40. http://www.sentex.net/~mwandel/jhead).
  41. http://pyexif.sourceforge.net/
  42. http://www.forminnovation.com/
  43. http://www.thethinktanksoftware.com/details.html
  44. http://sourceforge.net/project/?group_id=1322
  45. http://www.ghostscript.com/
  46. http://www.foolabs.com/xpdf/
  47. http://bmeps.sourceforge.net/
  48. http://isotropic.org/uw//postscript/imgtops2
  49. http://wvware.sourceforge.net/
  50. http://www.cc.gatech.edu/~bbb/2001/doc2png
  51. http://netpbm.sourceforge.net/doc/anytopnm.html
  52. ftp://ftp.astron.com/pub/file
  53. http://www.cs.utah.edu/research/projects/alpha1/urt.html
  54. http://www.ivtools.org/
  55. http://www.colorado-research.com/~gourlay/software/Graphics/Xmorph
  56. http://www.web3d.org/x3d/specifications/vrml/ISO_IEC_14772-All
  57. http://www.landfield.com/faqs/graphics/fileformats-faq/part3/section-24.html
  58. http://www.printers.ibm.com/R5PSC.NSF/web/archm
  59. http://www.w3.org/Graphics/SVG/
  60. http://netpbm.sourceforge.net/doc/pamtopfm.html
  61. http://www.openexr.org/about.html
  62. http://netpbm.sourceforge.net/doc/#overview
  63. http://netpbm.sourceforge.net/doc/#lbAD
  64. http://netpbm.sourceforge.net/doc/#impconv
  65. http://netpbm.sourceforge.net/doc/#lbAF
  66. http://netpbm.sourceforge.net/doc/#lbAG
  67. http://netpbm.sourceforge.net/doc/#commonoptions
  68. http://netpbm.sourceforge.net/doc/#directory
  69. http://netpbm.sourceforge.net/doc/#prognotes
  70. http://netpbm.sourceforge.net/doc/#lbAO
  71. http://netpbm.sourceforge.net/doc/#config
  72. http://netpbm.sourceforge.net/doc/#companion
  73. http://netpbm.sourceforge.net/doc/#phpnetpbm
  74. http://netpbm.sourceforge.net/doc/#othersoftware
  75. http://netpbm.sourceforge.net/doc/#otherfmt
  76. http://netpbm.sourceforge.net/doc/#lbAS
  77. http://netpbm.sourceforge.net/doc/#lbAT
