Ubuntu Manpage: netpbm - netpbm library overview

NAME

       netpbm - netpbm library overview

Overview Of Netpbm

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

        There  are  over 330 separate programs in the package, most of which have "pbm", "pgm", "ppm", "pam", or
       "pnm" in their names.  For example, pamscale(1) and giftopnm(1).

       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   Sourceforge    netpbm   project
       ⟨http://sourceforge.net/projects/netpbm⟩ .

       •

              Overview Of Netpbm ⟨#overview⟩

       •

              The Netpbm Formats ⟨#formats⟩

       •

              Implied Format Conversion ⟨#impconv⟩

       •

              Netpbm and Transparency ⟨#transparency⟩

       •

              The Netpbm Programs ⟨#programs⟩

       •

              Common Options ⟨#commonoptions⟩

       •

              Directory ⟨#directory⟩

       •

              How To Use The Programs ⟨#prognotes⟩

       •

              The Netpbm Library ⟨#libnetpbm⟩

       •

              netpbm-config ⟨#config⟩

       •

              Memory Usage ⟨#memoryusage⟩

       •

              CPU Usage ⟨#cpuusage⟩

       •

              Netpbm For Gimp ⟨#netpbmforgimp⟩

       •

              Companion Software ⟨#companion⟩

       •

              PHP-NetPBM ⟨#phpnetpbm⟩

       •

              Other Graphics Software ⟨#othersoftware⟩

       •

              Image Viewers ⟨#viewers⟩

       •

              Image Capturers ⟨#capturers⟩

       •

              Visual Graphics Software ⟨#visual⟩

       •

              Programming Tools ⟨#programmingtools⟩

       •

              Tools For Specific Graphics Formats ⟨#toolsforformats⟩

       •

              Document/Graphics Software ⟨#document⟩

       •

              Other ⟨#otherothersoftware⟩

       •

              Other Graphics Formats ⟨#otherfmt⟩

       •

              History ⟨#history⟩

       •

              Author ⟨#author⟩

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 and do not seek input from a user. The only programs that display graphics at all are
the very primitive display programs pamx and ppmsvgalib, and they don't do anything but that.

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 PNM format, generate it in the "plain" (aka "ascii") version
of the format, as opposed to the "raw" (aka "binary") version.

Note that the other Netpbm format, PAM, does not have plain and raw versions, so this option has
no effect on a program that generates PAM output.

This option was introduced in Netpbm 10.10 (October 2002). From Netpbm 10.32 (February 2006)
through Netpbm 10.62 (March 2013), the option is invalid with a program that generates PAM output
(instead of ignoring the option, the program fails).

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

Netpbm program directory(1)

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 pngtopam $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 $_ | pambrighten -value +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 <({ pngtopam 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 pbm(1), pgm(1), ppm(1), and pam(1).

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
Implied Format Conversion ⟨#impconv⟩ .

Programs that have "pnm" in their names read PBM, PGM, and PPM but unlike "ppm" programs, they
distinguish between those formats and their function depends on the format. For example, pnmtopng(1)
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 Implied Format Conversion
⟨#impconv⟩ .

Finally, there are subformats of PAM that are equivalent to PBM, PGM, and PPM respectively, and Netpbm
programs designed to read PBM, PGM, and/or PPM see those PAM images as if they were the former. For
example, ppmhist can analyze a PAM image of tuple type RGB (i.e. a color image) as if it were PPM.

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 pbm(1), pgm(1), ppm(1), and pam(1).

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.

A program that uses the PGM library subroutines to read an image can read a PAM image as well a PGM
image, if the PAM is a grayscale or black and white visual image. That canonically means the PAM has a
depth of 1 and a tuple type of GRAYSCALE or BLACKANDWHITE, but most Netpbm programs are fairly liberal
and will take any PAM at all, ignoring all but the first plane.

There is a similar implied conversion for PPM library subroutines reading PAM. There is nothing similar
for PBM, so if you need for a PBM program to read a PAM image, run it through pamtopnm.

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
pgm(1). pamcomp(1) 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 the PAM specification(1).

The Netpbm Library

       The  Netpbm  programming  library,  libnetpbm(1), 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.

Memory Usage

An important characteristic that varies among graphics software is how much memory it uses, and how.
Does it read an entire image into memory, work on it there, then write it out all at once? Does it read
one and write one pixel at a time? In Netpbm, it differs from one program to the next, but there are
some generalizations we can make.

Most Netpbm programs keep one row of pixels at a time in memory. Such a program reads a row from an
input file, processes it, then writes a row to an output file. Some programs execute algorithms that
can't work like that, so they keep a small window of rows in memory. Others must keep the entire image
in memory. If you think of what job the program does, you can probably guess which one it does.

When Netpbm keeps a pixel in memory, it normally uses a lot more space for it than it occupies in the
Netpbm image file format.

The older programs (most of Netpbm) use 12 bytes per pixel. This is true even for a PBM image, for which
it only really takes one bit to totally describe the pixel. Netpbm does this expansion to make
implementing the programs easier -- it uses the same format regardless of the type of image.

Newer programs use the "pam" family of library functions internally, which use memory a little
differently. These functions are designed to handle generic tuples with a variable numbers of planes, so
no fixed size per-tuple storage is possible. A program of this type uses 4 bytes per sample (a tuple is
composed of samples), plus a pointer (4-8 bytes) per tuple. In a graphic image, a tuple is a pixel. So
an ordinary color image takes 16-20 bytes per pixel.

When considering memory usage, it is important to remember that memory and disk storage are equivalent in
two ways:

• Memory is often virtual, backed by swap space on disk storage. So accessing memory may mean doing
disk I/O.

• Files are usually cached and buffered, so that accessing a disk file may just mean accessing
memory.

This means that the consequences of whether a program works from the image file or from a memory copy are
not straightforward.

Note that an image takes a lot less space in a Netpbm format file, and therefore in an operating system's
file cache, than in Netpbm's in-memory format. In non-Netpbm image formats, the data is even smaller.
So reading through an input file multiple times instead of keeping a copy in regular memory can be the
best use of memory, and many Netpbm programs do that. But some files can't be read multiple times. In
particular, you can't rewind and re-read a pipe, and a pipe is often the input for a Netpbm program.
Netpbm programs that re-read files detect such input files and read them into a temporary file, then read
that temporary file multiple times.

A few Netpbm programs use an in-memory format that is just one bit per pixel. These are programs that
convert between PBM and a format that has a raster format very much like PBM's. In this case, it would
actually make the program more complicated (in addition to much slower) to use Netpbm's generic 12 byte
or 8 byte pixel representation.

By the way, the old axiom that memory is way faster than disk is not necessarily true. On small systems,
it typically is true, but on a system with a large network of disks, especially with striping, it is
quite easy for the disk storage to be capable of supplying data faster than the CPU can use it.

CPU Usage

People sometimes wonder what CPU facilities Netpbm programs and the Netpbm programming library use. The
programs never depend on particular features existing (assuming they're compiled properly), but the speed
and cost of running a program varies depending upon the CPU features.

Note that when you download a binary that someone else compiled, even though it appears to be compiled
properly for your machine, it may be compiled improperly for that machine if it is old, because the
person who compiled it may have chosen to exploit features of newer CPUs in the line. For example, an
x86 program may be compiled to use instructions that are present on an 80486, but not on an 80386. You
would probably not know this until you run the program and it crashes.

But the default build options almost always build binaries that are as backward compatible with old CPUs
as possible. An exception is a build for a 64 bit x86 CPU. While the builder could build a program that
runs on a 32 bit x86, it does not do so by default. A default build builds a program will not run on an
older 32-bit-only x86 CPU.

One common build option is to use MMX/SSE operands with x86 CPUs. Those are not available on older x86
CPUs. The builder by default does not generate code that uses MMX/SSE when building for 32 bit x86 CPUs,
but does when building for 64 bit x86.

One area of particular importance is floating point arithmetic. The Netpbm image formats are based on
integers, and Netpbm arithmetic is done with integers where possible. But there is one significant area
that is floating point: programs that must deal with light intensity. The Netpbm formats use integers
that are proportional to brightness, and brightness is exponentially related to light intensity. The
programs have to keep the intermediate intensity values in floating point in order not to lose precision.
And the conversion (gamma function) between the two is heavy-duty floating point arithmetic.

Programs that mix pixels together have to combine light intensity, so they do heavy floating point.
Three of the most popular Netpbm programs do that: pamscale(1) (shrink/expand an image), pamcomp(1)
(overlay an image over another one), and pamditherbw(1) (Make a black and white image that approximates a
grayscale image).

The Netpbm image formats use 16 bit integers. The Netpbm code uses "unsigned int" size integers to work
with them.

Netpbm For Gimp

       The  Gimp  is  a visual image editor for Unix and X, so it does the kinds of things that Netpbm does, but
       interactively in a user-friendly way.  The Gimp knows a  variety  of  graphics  file  formats  and  image
       transformations, but you can extend it with plugins.

       A  particularly easy way to write a Gimp plugin is to write a Netpbm program (remember that a fundamental
       mission  of  Netpbm  is  make  writing  image  manipulation  programs  easy)  and  then  use  netpbm2gimp
       ⟨http://netpbm2gimp.sourceforge.net/⟩  to compile that same source code into a Gimp plugin.

       You  can  turn  a  program that converts from a certain graphics file format to Netpbm format into a Gimp
       load plugin.  Likewise, you can turn a program that converts to a certain  graphics  format  from  Netpbm
       format into a Gimp store plugin.  Finally, a program that transforms images in Netpbm format can become a
       process plugin.

       And the netpbm2gimp project has already packaged for you a few hundred of the  Netpbm  programs  as  Gimp
       plugins.   With  this  package  you  can,  for  example, edit an image in any of the arcane graphics file
       formats that Netpbm understands but no other image editor in existence does.

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 PHP-NetPBM ⟨http://sourceforge.net/projects/phpnetpbm⟩ , 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.

Command Line Programs
ImageMagick does many of the same things - mainly the more popular ones - that Netpbm does, including
conversion between popular formats and basic editing. convert, mogrify, montage, and animate are popular
programs from the ImageMagick package. ImageMagick runs on Unix, Windows, Windows NT, Macintosh, and
VMS.

ImageMagick also contains the program display, which is a viewer ⟨#viewers⟩ and visual editor ⟨#visual⟩
.

Image Viewers
The first thing you will want to make use of any of these tools is a viewer. (On GNU/Linux, you can use
Netpbm's pamx or 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
ftp://ftp.ibiblio.org/pub/Linux/apps/graphics/viewers/svga
⟨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 pamcut(1).

See the -s option to zgv.

For the X inclined, there is also xzgv.

xwud (X Window Undump) is a classic application program in the X Window System that displays an image in
an X window. It takes the special X Window Dump format as input; you can use Netpbm's pnmtoxwd(1) to
create it. You're probably better off just using Netpbm's pamx(1).

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 mplayer(1) or xine
⟨http://sourceforge.net/projects/xine⟩ .

See ftp://metalab.unc.edu/pub/Linux/apps/graphics/viewers/X
⟨ftp://metalab.unc.edu/pub/Linux/apps/graphics/viewers/X⟩ .

Image Capturers
xwd (X Window Dump), a classic application program in the X Window System, captures the contents of an X
window, in its own special image format, called X Window Dump File. You can use Netpbm's xwdtopnm(1) to
turn it into something more useful.

fbdump ⟨http://www.rcdrummond.net/fbdump/⟩ Capturers the current contents of a video display on the
local computer and generates a PPM image of it. It works with Linux framebuffer devices.

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.

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.

Gimp is a visual image editor for Unix and the X Window System, in the same category as the more famous,
less capable, and much more expensive Adobe Photoshop, etc. for Windows. See http://www.gimp.org
⟨http://www.gimp.org⟩ . And you can add most of Netpbm's function to Gimp using Netpbm2gimp
⟨http://netpbm2gimp.sourceforge.net/⟩ .

ImageMagick contains the program display, which is another visual image editor. It has fewer functions
than Gimp. This program uses the X Window System. The package also contains command line
⟨#othercmdline⟩ graphics programs.

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 gd
⟨https://github.com/libgd/libgd⟩ . Netpbm contains a C library for drawing images (libnetpbm's "ppmd"
routines), but it is not as capable or documented as gd. There are wrapper libraries available for Perl,
PHP, and other language.

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.

Cairo ⟨http://cairographics.org/⟩ is similar.

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 k5n.us
⟨http://www.k5n.us/Ilib.php⟩ . Netpbm also includes character drawing functions in the libnetpbm(1)
library, but they do not have as fancy font capabilities (see ppmdraw(1) for an example of use of the
Netpbm character drawing functions).

Pango ⟨http://www.pango.org/⟩ is another text rendering library, with an emphasis on
internationalization.

Pango and Cairo complement each other and work well together.

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
mencode, which is part of the mplayer(1) package, creates movie files. It's like a much more advanced
version of ppmtompeg(1), without the Netpbm building block simplicity.

MJPEGTools ⟨http://mjpeg.sourceforge.net⟩ is software for dealing with the MJPEG movie format.

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 pamtogif and giftopnm to connect up to all the Netpbm utilities. See
http://www.lcdf.org/gifsicle ⟨http://www.lcdf.org/gifsicle⟩ .

To convert an image of text to text (optical character recognition - OCR), use gocr (think of it as an
inverse of pbmtext). See http://jocr.sourceforge.net/ ⟨http://jocr.sourceforge.net/⟩ .

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

Other versions of Netpbm's pnmtopng/pngtopam are at http://www.schaik.com/png/pnmtopng.html" (1).

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.

pngwriter ⟨http://pngwriter.sourceforge.net⟩ 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 ( http://www.ijg.org) ⟨http://www.ijg.org⟩ JPEG library.

Some tools to deal with EXIF files (see also Netpbm's jpegtopnm(1) and pnmtojpeg(1)):

To dump (interpret) an EXIF header: Exifdump (( http://www.math.u-psud.fr/~bousch/exifdump.py)
⟨http://www.math.u-psud.fr/~bousch/exifdump.py⟩ ) or Jhead ⟨http://www.sentex.net/~mwandel/jhead⟩ .

A Python EXIF library and dumper: http://pyexif.sourceforge.net. ⟨http://pyexif.sourceforge.net.⟩

Here's some software to work with IOCA (Image Object Content Architecture): ImageToolbox
⟨http://www.forminnovation.com⟩ ($2500, demo available). This can convert from TIFF -> IOCA and back
again.

Ameri-Imager ⟨https://ameri-imager.software.informer.com/⟩ is an image and video editor. ($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 The Pnm2ppa /Sourceforge Project
⟨http://sourceforge.net/projects/pnm2ppa⟩

DjVuLibre is a package of software for using the DjVu format. It includes viewers, browser plugins,
decoders, simple encoders, and utilities. The encoders and decoders can convert between DjVu and PNM.
See
the DjVu website. ⟨http://djvu.sourceforge.net/⟩

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 Ghostscript ⟨http://www.ghostscript.com/⟩ , 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.

xpdf ⟨http://www.foolabs.com/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.

bmpp(1) converts from Netpbm and other formats to PDF.

Two packages that produce more kinds of Encapsulated Postscript than the Netpbm programs, including
compressed kinds, are bmpp(1) and imgtops ⟨http://imgtops.sourceforge.net/⟩ .

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.

wvware ⟨http://wvware.sourceforge.net⟩ 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.

Document Printer ⟨http://www.verypdf.com/artprint⟩ converts various print document formats (Microsoft
Word, PDF, HTML, etc.) to various graphic image formats. ($38, Windows only).

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 anytopnm(1)
program depends on file. See ftp://ftp.astron.com/pub/file ⟨ftp://ftp.astron.com/pub/file⟩ .

The Utah Raster Toolkit from the Geometric Design And Computation group in the Department of Computer
Science at University of Utah 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.

Ivtools is a suite of free X Window System 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 http://www.ivtools.org ⟨http://www.ivtools.org⟩ .

Chisato Yamauchi <cyamauch@ir.isas.jaxa.jp> has written a free c/Fortran graphic library: EGGX/ProCall
⟨http://www.ir.isas.jaxa.jp/~cyamauch/eggx_procall/⟩ . He says he tried to write the ultimate easy-to-
use graphic kit for X. It is for drawing upon an X11 window, but for storage, it outputs PPM. He
suggests Netpbm to convert to other formats.

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
http://xmorph.sourceforge.net/ ⟨http://xmorph.sourceforge.net/⟩ .

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.

• WebP was announced by Google in October 2010 as a more compressed replacement for JFIF (aka JPEG)
on the web.

• JPEG-LS is similar to JFIF (aka JPEG) except that it is capable of representing all the
information in any raster image, so you could convert from, say, PNM, without losing any
information. CharLS is a programming library for JPEG-LS.

• Lossless JPEG is a similarly lossless variation of JPEG. It predates every other lossless JPEG
variation, but had only brief interest. You can find code for encoding and decoding Lossless JPEG
on GitHub ⟨https://github.com/thorfdbg/libjpeg⟩ .

• JPEG XR offers greater dynamic range, a wider range of colors, and more efficient compression than
JFIF (aka JPEG). Windows and Internet Explorer understand this format, starting with Windows 7
and Internet Explorer 9, along with many other programs. This format was previously known as
Windows Media Photo and HD Photo.

• Direct Draw Surface (DDS)is the de facto standard wrapper format for S3 texture compression, as
used in all modern realtime graphics applications. Besides Windows-based tools, there is a Gimp
plugin for this format.

• DjVu is a web-centric format and software platform for distributing documents and images.
Promoters say it is a good replacement for PDF, PS, TIFF, JFIF(JPEG), and GIF for distributing
scanned documents, digital documents, or high-resolution pictures, because it downloads faster,
displays and renders faster, looks nicer on a screen, and consumes less client resources than
competing formats.

For more information, see
the DjVu website. ⟨http://djvu.sourceforge.net/⟩

•

VRML (Virtual Reality Modelling Language) ⟨http://www.web3d.org/x3d/specifications/vrml⟩

•

CALS (originated by US Department Of Defense, favored by architects). It is described in this
1997 listing of graphics formats:
http://www.faqs.org/faqs/graphics/fileformats-faq/part3/
⟨http://www.faqs.org/faqs/graphics/fileformats-faq/part3/⟩ . CALS has at times been an
abbreviation of various things, all of which appear to be essentially the same format, but
possibly slightly different:

• Computer Aided Logistics Support

• Computer Aided Acquisition and Logistics Support

• Continuous Acquisition and Life-cycle Support

• Commerce At Light Speed

The US Navy publishes specs ⟨https://www.navsea.navy.mil/Home/Warfare-Centers/NSWC-
Carderock/Resources/Technical-Information-Systems/IETMs/Specifications-Standards/CALS-Standards/⟩
for it.

•

array formats dx, general, netcdf, CDF, hdf, cm

•

CGM+

• HDR formats OpenEXR, SGI TIFF LogLuv, floating point TIFF, Radiance RGBE

• Windows Meta File (.WMF). Libwmf converts from WMF to things like Latex, PDF, PNG. Some of these
can be input to Netpbm.

• Microsoft Word .doc format. Microsoft keeps a proprietary hold on this format. Any software you
see that can handle it is likely to cost money.

• RTF

•

DXF (AutoCAD)

•

IOCA (Image Object Content Architecture) The specification of this format is documented by IBM:
Data Stream and Object Architectures: Image Object Content Architecture Reference
⟨http://publibz.boulder.ibm.com/epubs/pdf/c3168055.pdf⟩ . See above for software that processes
this format.

• OpenEXR is an HDR format (like PFM(1)). See
http://www.openexr.com ⟨http://www.openexr.com⟩ .

• 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 similar 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.

•

MJPEG ⟨http://en.wikipedia.org/wiki/MJPEG⟩ movie format.

• YUV4MPEG2 is a movie format whose purpose is similar to that of the Netpbm formats for still
images. You use it for manipulating movies, but not for storing or transmitting them. The only
known use of the format is with MJPEGTools ⟨http://mjpeg.sourceforge.net⟩ . The programs pnmtoy4m
and y4mtopnm (and predecessors ppmtoy4m and y4mtoppm) in that package convert between a Netpbm
stream and a YUV4MPEG2 stream. As you might guess from the name, YUV4MPEG2 uses a YUV
representation of data, which is more convenient than the Netpbm formats' RGB representation for
working with data that is ultimately MPEG2.

History

       Netpbm  has  a  long  history, starting with Jef Poskanzer's Pbmplus package in 1988.  See the Netpbm web
       site(1) for details.

       The file doc/HISTORY in the Netpbm source code contains a detailed change 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.

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/index.html