User manual for Netpbm(0) User manual for Netpbm(0)NAME
netpbm - netpbm library overview
Overview Of NetpbmNetpbm 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,
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 cre‐
ate 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⟩ .
Table Of Contents
·
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 charac‐
teristic of Netpbm programs is that they are simple, fundamental build‐
ing 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 wher‐
ever the underlying system can. There may be exceptions where the pro‐
grams 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_mes‐
sage() service of the Netpbm library).
-version
Instead of doing anything else, report the version of the lib‐
netpbm 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):
Netpbmprogramdirectory(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 $_ | 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 hypotheti‐
cal 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(5) , pgm(5) ,
ppm(5) , and pam(5)
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 for‐
mats, and as a package Netpbm lets you do more graphics format conver‐
sions 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 pix‐
els 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 pro‐
duces 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 individ‐
ual 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 exam‐
ple, 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 for‐
mat.
The formats are described in the specifications of pbm(5) , pgm(5) ,
ppm(5) , and pam(5)
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, ignor‐
ing all but the first plane.
There is a similar implied conversion for PPM library subroutines read‐
ing 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 sepa‐
rate (slightly redefined) PGM image. In this pseudo-PGM, what would
normally be a pixel's intensity is instead an opaqueness value. See
pgm(5)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 pri‐
marily 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 rec‐
ognize and generate a PAM image with tuple type RGB_ALPHA or
GRAYSCALE_ALPHA, which contains a plane for the transparency informa‐
tion. See thePAMspecification(5)The Netpbm Library
The Netpbm programming library, libnetpbm(3) , 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 pro‐
gram reads and writes the Netpbm formats, you can use it with any for‐
mats.
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 typ‐
ically 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 mem‐
ory, 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 imple‐
menting 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 ordi‐
nary 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-mem‐
ory 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 pro‐
grams do that. But some files can't be read multiple times. In par‐
ticular, 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 actu‐
ally 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 particu‐
lar features existing (assuming they're compiled properly), but the
speed and cost of running a program varies depending upon the CPU fea‐
tures.
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 instruc‐
tions 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 pro‐
grams 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 pro‐
grams 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 transforma‐
tions, 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 for‐
mat 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 SoftwareNetpbm contains primitive building blocks. It certainly is not a com‐
plete graphics software library.
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 Sys‐
tem, 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 con‐
tents 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 dis‐
plays 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 mainte‐
nance, 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 Photo‐
shop, etc. for Windows. See http://www.gimp.org ⟨http://www.gimp.org⟩
. And you can add most of Netpbm's function to The Gimp using
Netpbm2gimp ⟨http://netpbm2gimp.sourceforge.net/⟩ .
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 ⟨http://www.boutell.com/gd⟩ . Netpbm contains a C library for
drawing images (libnetpbm's 'ppmd' routines), 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 program‐
ming 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(3)
library, but they do not have as fancy font capabilities (see ppm‐
draw(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://topo.math.u-
psud.fr/~bousch/exifdump.py) ⟨http://topo.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 Architec‐
ture): ImageToolbox ⟨http://www.forminnovation.com⟩ ($2500, demo
available). This can convert from TIFF -> IOCA and back again. Ameri-
Imager(1)
($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 util‐
ities. 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 con‐
verts from Postscript and PDF to PNM. It effectively renders the docu‐
ment into images of printed pages. pstopnm is nothing but a convenient
wrapper for Ghostscript ⟨http://www.ghostscript.com/⟩ , and in particu‐
lar Netpbm-format device drivers that are part of it. pnmtops and pbm‐
toepsi 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 cre‐
ates 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.
Two packages that produce more kinds of Encapsulated Postscript than
the Netpbm programs, including compressed kinds, are bmeps
⟨http://bmeps.sourceforge.net/⟩ 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 graphi‐
cally.
wvware ⟨http://wvware.sourceforge.net⟩ converts a Microsoft Word docu‐
ment (.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 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.
The website of the Geometric Design And Computation group
⟨http://www.cs.utah.edu/gdc⟩ in the Department of Computer Science at
University of Utah used to (ca. 2002) have information on the Utah
Raster Toolkit, but now it doesn't.
Ivtools is a suite of free X Window System drawing editors for Post‐
script, 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/For‐
tran 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 sug‐
gests 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 com‐
pletely 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 pro‐
grams. ImageMagick is probably the most used free image format con‐
verter and it also handles lots of formats Netpbm does not.
· WebP was announced by Google in October 2010 as a more com‐
pressed replacement for JFIF (aka JPEG) on the web.
· 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 Win‐
dows 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 dis‐
tributing documents and images. Promoters say it is a good
replacement for PDF, PS, TIFF, JFIF(JPEG), and GIF for dis‐
tributing scanned documents, digital documents, or high-resolu‐
tion 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 archi‐
tects). It is described in this 1997 listing of graphics for‐
mats:
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(1)
for it.
The web page http://www.sollers.ca
⟨http://www.sollers.ca/projects/cals2tiff/⟩ describes a program
for converting from CALS to TIFF.
·
array formats dx, general, netcdf, CDF, hdf, cm
·
CGM+
· HDR formats OpenEXR, SGI TIFF LogLuv, floating point TIFF, Radi‐
ance 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 anti‐
quated format used by the Xv program. In Netpbm circles, it is
best known for the fact that it is very similar to Netpbm for‐
mats 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 manipulat‐
ing movies, but not for storing or transmitting them. The only
known use of the format is with MJPEGTools
⟨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 rep‐
resentation for working with data that is ultimately MPEG2.
HistoryNetpbm has a long history, starting with Jef Poskanzer's Pbmplus pack‐
age in 1988. See the Netpbmwebsite(1)
for details.
The file doc/HISTORY in the Netpbm source code contains a detailed
change history release by release.
AuthorNetpbm is based on the Pbmplus package by Jef Poskanzer, first distrib‐
uted in 1988 and maintained by him until 1991. But the package con‐
tains work by countless other authors, added since Jef's original work.
In fact, the name is derived from the fact that the work was contrib‐
uted by people all over the world via the Internet, when such collabo‐
ration 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.
netpbm documentation 22 February 2009 User manual for Netpbm(0)
