netpbm (1) Linux Manual Page
NAME
netpbm – package of graphics manipulation programs and libraries
DESCRIPTION
Netpbm is a package of graphics programs and programming libraries.
There are over 220 separate programs in the package, most of which have "pbm", "pgm", "ppm", or "pnm" in their names. For example, pnmscale and giftopnm.
For example, you might use pnmscale to shrink an image by 10%. Or use pnmcomp 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.
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 over 80 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 the section "Implied Format Conversion" below.
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, pnmtogif creates a black and white GIF output image if its input is PBM or PGM, but a color GIF output image if its input is PPM. And pnmscale produces an output image of the same format as the input. A ppmscale program would read all three PNM input formats, but would see them all as PPM and would always generate PPM output.
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 man pages pbm(5), pgm(5), ppm(5), and pam(5),
Implied Format Conversion
A program that uses the PGM library 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.
A program that uses the PPM library 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.
Netpbm and Transparency
In many graphics format, 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 it an opaqueness value. See pgm(5). pnmcomp is an example of a program that uses a PGM transparency mask.
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 man page.
Common Options
There are a few options that are present on all programs that are based on the Netpbm libraries, including virtually all Netpbm programs. These are not mentioned in the individual man pages for the programs.
-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 libraries). -version- Instead of doing anything else, report the version of the
libpbmlibrary 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 libraries are installed at the same time, so this tells you the version of the program and all the other Netpbm libraries and files it uses as well.Here is a directory of the Netpbm programs. You can also use
man -kto search for a program that does what you want.
Converters
ppmtompeg- convert series of PPM frames to an MPEG movie
jpegtopnm- convert JFIF/JPEG/EXIF file to Netpbm format
pnmtojpeg- convert PPM to JPEG/JFIF/EXIF format
anytopnm- convert any graphics format to Netpbm format
bmptoppm- convert Windows or OS/2 Bitmap file to PPM
ppmtobmp- convert PPM to Windows or OS/2 Bitmap file
winicontoppm- convert Windows icon file to PPM
ppmtowinicon- convert PPM to Windows icon file
giftopnm- convert GIF to portable anymap
ppmtogif- convert PPM to GIF
pnmtopng- convert Netpbm format to Portable Network Graphics
pngtopnm- convert PNG (Portable Network Graphics) to Netpbm formats
palmtopnm- convert Palm pixmap to Netpbm formats
pnmtopalm- convert Netpbm formats to Palm pixmap
jbigtopbm- convert JBIG BIE (compressed bitmap) to PBM
pamtopnm- convert a PAM image to PBM, PGM, or PPM
pbmtojbig- convert PBM to JBIG BIE (compressed bitmap)
pnmtofiasco- convert Netpbm image to Fiasco (wfa) highly compressed format
fiascotopnm- convert Fiasco (wfa) highly compressed format to Netpbm image
hpcdtoppm- convert photo CD to PPM
pbmtonokia- convert PBM to Nokia Smart Messaging Format (SMF)
pbmtowbmp- convert PBM to WAP (Wireless App Protocol) Wireless Bitmap
wbmptopbm- convert WAP (Wireless App Protocol) Wireless Bitmap to PBM
neotoppm- convert Atari Neochrome (.neo) image to PPM
ppmtoneo- convert PPM image to Atari Neochrome (.neo)
pbmtomda- convert from PBM to Microdesign (for Amstrad PCWs)
mdatopbm- convert from Microdesign (for Amstrad PCWs) to PBM
atktopbm- convert Andrew Toolkit raster object to PBM
pbmtoatk- convert PBM to Andrew Toolkit raster object
brushtopbm- convert Xerox doodle brushes to PBM
cmuwmtopbm- convert CMU window manager format to PBM
g3topbm- convert Group 3 FAX to PBM
pbmtog3- convert PBM to Group 3 FAX
icontopbm- convert Sun icon to PBM
pbmtoicon- convert PBM to Sun icon
gemtopnm- convert GEM .img format to PBM or pixmap
macptopbm- convert MacPaint to PBM
pbmtomacp- convert PBM to MacPaint
mgrtopbm- convert MGR format to PBM
pbmtomgr- convert PBM to MGR format
pi3topbm- convert Atari Degas .pi3 to PBM
pbmtopi3- convert PBM to Atari Degas .pi3
xbmtopbm- convert X10 or X11 bitmap to PBM
pbmtoxbm- convert PBM to X11 bitmap
pbmtox10bm- convert PBM to X10 bitmap
ybmtopbm- convert Bennet Yee "face" file into PBM
pbmtoybm- convert PBM into Bennet Yee "face" file
pbmto10x- convert PBM to Gemini 10x printer graphics
pbmtoascii- convert PBM to ASCII graphic form
asciitopgm- convert ASCII character graphics to PGM
pbmtobbnbg- convert PBM to BBN BitGraph graphics
pbmtocmuwm- convert PBM to CMU window manager format
pbmtoepson- convert PBM to Epson printer graphics
pbmtogem- convert PBM into GEM .img file
pbmtogo- convert PBM to GraphOn graphics
pbmtolj- convert PBM to HP LaserJet black and white graphics
ppmtolj- convert PPM to HP LaserJet color graphics (PCL)
pjtoppm- convert HP PaintJet file to PPM
ppmtopj- convert PPM to HP PaintJet file
thinkjettopbm- convert HP Thinkjet printer stream to PBM
pbmtoplot- convert PBM into Unix plot(5) file
pbmtoptx- convert PBM to Printronix graphics
pbmtozinc- convert PBM to Zinc Interface Library icon
fitstopnm- convert FITS format to portable anymap
pnmtofits- convert Netpbm formats to FITS format
fstopgm- convert Usenix FaceSaver(tm) format to PGM
pgmtofs- convert PGM to Usenix FaceSaver(tm) format
hipstopgm- convert HIPS format to PGM
lispmtopgm- convert a Lisp Machine bitmap file into PGM format
pgmtolispm- convert PGM into Lisp Machine format
pnmtops- convert Netpbm formats to Postscript
pstopnm- convert Postscript to Netpbm formats
psidtopgm- convert PostScript "image" data to PGM
pbmtolps- convert PBM image to Postscript using lines
pbmtoepsi- convert a PBM image to encapsulated Postscript preview bitmap
pbmtopsg3- convert PBM images to Postscript using G3 fax compression.
rawtopgm- convert raw grayscale bytes to PGM
pgmtopbm- convert PGM to PBM
gouldtoppm- convert Gould scanner file to PPM
ilbmtoppm- convert IFF ILBM to PPM
ppmtoilbm- convert PPM to IFF ILBM
imgtoppm- convert Img-whatnot to PPM
mtvtoppm- convert MTV ray-tracer output to PPM
pcxtoppm- convert PC Paintbrush format to PPM
pgmtoppm- colorize a portable graymap into a PPM
pi1toppm- convert Atari Degas .pi1 to PPM
ppmtopi1- convert PPM to Atari Degas .pi1
picttoppm- convert Macintosh PICT to PPM
ppmtopict- convert PPM to Macintosh PICT
qrttoppm- convert QRT ray-tracer output to PPM
rawtoppm- convert raw RGB bytes to PPM
sldtoppm- convert an AutoCAD slide file into a PPM
spctoppm- convert Atari compressed Spectrum to PPM
sputoppm- convert Atari uncompressed Spectrum to PPM
tgatoppm- convert TrueVision Targa file to PPM
ppmtotga- convert PPM to TrueVision Targa file
ximtoppm- convert Xim to PPM
xpmtoppm- convert XPM format to PPM
ppmtoxpm- convert PPM to XPM format
yuvtoppm- convert Abekas YUV format to PPM
eyuvtoppm- convert Encoder/Berkeley YUV format to PPM
ppmtoeyuv- convert PPM to Encoder/Berkeley YUV format
ppmtoyuv- convert PPM to Abekas YUV format
ppmtoyuvsplit- convert PPM to 3 subsampled raw YUV files
yuvsplittoppm- merge 3 subsampled raw YUV files to one PPM
ppmtoacad- convert PPM to AutoCAD database or slide
ppmtoicr- convert PPM to NCSA ICR graphics
ppmtopcx- convert PPM to PC Paintbrush format
ppmtopgm- convert PPM to portable graymap
ppmtopuzz- convert PPM to X11 "puzzle" file
rasttopnm- convert Sun raster file to Netpbm formats
pnmtorast- convert Netpbm formats to Sun raster file
tifftopnm- convert TIFF file to portable anymap
pnmtotiff- convert Netpbm formats to TIFF RGB file
pnmtotiffcmyk- convert Netpbm formats to TIFF CMYK file
xwdtopnm- convert X10 or X11 window dump to Netpbm formats
pnmtoxwd- convert Netpbm formats to X11 window dump
pnmtoplainpnm- convert regular Netpbm format image into plain Netpbm format
pbmtopgm- convert PBM file to PGM by averaging areas
411toppm- convert 411 (Sony Mavica) to PPM
ppmtosixel- convert PPM to DEC sixel format
ppmtouil- convert PPM to Motif UIL icon file
sbigtopgm- convert Santa Barbara Instrument Group CCD file to PGM
vidtoppm- convert Parallax XVideo JPEG to sequence of PPM files
pnmtorle- convert PNM to Utah Raster Toolkit (urt/rle) file
rletopnm- convert Utah Raster Toolkit (urt/rle) file to PNM
ppmtoleaf- convert PPM to Interleaf
leaftoppm- convert Interleaf to PPM
bioradtopgm- convert Biorad confocal image to PGM
pbmtoln03- convert PGM image to Dec LN03+ Sixel image
pbmtopk- convert PBM image to packed format (PK) font
pktopbm- convert packed format (PK) font to PBM image
Image Generators
All of these generate Netpbm format output.
pbmmake- create a blank PBM image of a specified size
ppmmake- create a PPM image of a specified size and color
pgmramp- generate a grayscale ramp
ppmpat- create a pretty PPM image
ppmrainbow- create a spectrum-like image with colors fading together.
pgmnoise- create a PGM image of white noise
pbmtext- render text into a PBM image
pbmupc- create a Universal Product Code PBM image
ppmcie- generate a CIE color map PPM image
pbmpage- create a printer test pattern page in PBM format
ppmcolors- create a color map (PPM image) containing all possible colors of given maxval
Image Editors
All of these work on the Netpbm formats
ppmlabel- Add text to an image
pnmshadow- add a shadow to an image so it looks like it’s floating
ppmbrighten- brighten or dim an image — change saturation and value
ppmdim- dim an image – different way from ppmbrighten
pbmreduce- reduce a PBM N times, using Floyd-Steinberg
pgmnorm- normalize contrast in a PGM image
ppmnorm- normalize contrast in a PPM image
pbmpscale- enlarge a PBM image with edge smoothing
pnmscale- scale an image with high precision
pnmscalefixed- scale an image quickly with low precision
pnmenlarge- enlarge an image N times
ppmdither- ordered dither for color images
pnmcolormap- Choose the N best colors to represent an image; create a colormap
pnmremap- Replace colors in an image with those from a color map
ppmquant- quantize colors in a color image down to fewer colors
pnmquant- quantize colors/shades in a color or grayscale image down to fewer
ppmquantall- quantize colors on many files
ppmrelief- run a Laplacian Relief filter on a PPM
pnmarith- perform arithmetic on two images
pnmcat- concatenate images
pnmpad- add borders to an image
pnmcomp- create composite (overlay) of images
ppmmix- mix (overlay) two images.
pnmcrop- crop all like-colored borders off an image
pamcut- select a rectangular region from an image
pnmcut- obsolete version of
pamcut(kept because it may have fewer bugs) pamdice- slice an image into many horizontally and/or vertically
pamdeinterlace- remove every other row from an image
pamchannel- extract a single plane (channel, e.g. R, G, or B) from an image
pnmdepth- change the maxval in an image
pnmflip- perform one or more flip operations on an image
pamstretch- scale up an image by inserting interpolated pixels
pamstretch-gen- scale by non-integer values using pamstretch and pnmscale
pnminvert- invert an image
pnmgamma- perform gamma correction on an image
pnmhisteq- histogram equalize image to increase contrast
pnmmargin- add a margin to an image
pnmpaste- paste a rectangle into an image
pnmrotate- rotate an image
pnmshear- shear an image
pnmsmooth- smooth am image
pnmtile- replicate an image into a specified size
pbmclean- remove lone pixels (snow) from a PBM image
pnmalias- antialias an image
ppmchange- change all of one color to another in PPM image
pnmnlfilt- filter an image by replacing each pixel with a function of nearby pixels
ppmshift- shift lines of PPM image left or right a random amount
ppmspread- move pixels of PPM image a random amount
pnmconvol- general MxN convolution on an image
rgb3toppm- combine three portable graymaps into one PPM
ppmtorgb3- separate a PPM into three portable graymaps
pbmlife- apply Conway’s rules of Life to a PBM image
ppmdist- map colors to high contrast grayscales arbitrarily
ppmntsc- adjust colors so they are legal for NTSC or PAL television
Image Analyzers
These all work on the Netpbm formats as input.
pnmfile- describe an image’s vital characteristics
pnmpsnr- measure difference between two images
pgmedge- edge-detect a PGM image
pgmenhance- edge-enhance a PGM image
pgmslice- print grayscale values for a row or column of a PGM image
pgmtexture- calculate textural features on a PGM image
pgmhist- print a histogram of the values in a PGM image
ppmhist- print a histogram of a PPM
pnmhistmap- draw a histogram of a PGM or PPM
ppmtomap- generate a map of all colors in an image
ppm3d- generate a blue/green 3D glasses image from two images
Miscellaneous
ppmsvgalib- display a PPM image on a Linux virtual console using Svgalib
pbmmask- create a mask bitmap from a regular bitmap
ppmcolormask- create mask of areas of a certain color in an image
pnmsplit- split a multi-image Netpbm file into multiple 1-image files
pnmindex- build a visual index of a bunch of Netpbm images
pcdindex- build a visual index of a photo CD from PCD overview file
pnmmontage- build multiple Netpbm images into a single montage image
pgmbentley- Bentleyize a PGM image
pgmcrater- create cratered terrain by fractal forgery
pamoil- turn a PNM or PAM image into an oil painting
ppmforge- fractal forgeries of clouds, planets, and starry skies
pgmkernel- generate a convolution kernel
ppmtv- Make an image lined so it looks like an old TV
pbmto4425- Display PBM image on AT&T 4425 ASCII terminal with gfx chars
Uncatalogued As Yet
pnmtoddifpnmtosgipnmtosirppmflashppmqvgappmtomitsuppmtopjxlsgitopnmsirtopnmspottopgmxvminitoppmzeisstopnm
The Netpbm Libraries
The Netpbm programming libraries, libpbm(3), libpgm(3), libppm(3), and libpnm(3), make it easy to write programs that manipulate graphic images. Their main function is to read and write files in the Netpbm format, 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 libraries also contain some utility functions, such as character drawing and RGB/YCrCb conversion.
The libraries have the conventional C linkage. Virtually all programs in the Netpbm package are based on the Netpbm libraries.
Application Notes
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 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.
Other Graphics Software
Netpbm contains primitive building blocks. It certainly is not a complete graphics library.
The first thing you will need to make use of any of these tools is a viewer. For the X inclined, there is xzgv. See ftp://metalab.unc.edu/pub/Linux/apps/graphics/viewers/X.
xloadimage and its extension xli are also common ways to display a graphic image in X.
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.
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 http://www.gimp.org.
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 program depends on file. See 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. http://www.cs.utah.edu/research/projects/alpha1/urt.html gives some information on the Utah Raster Toolkit, but does not tell where to get it.
There are some Netpbm-like graphics tools distributed by the Army High Performance Computing Research Center at http://www.arc.umn.edu/gvl-software/media-tools.html. These operate directly on non-Netpbm format images, so they aren’t included in the Netpbm package. However, you can use them with any image format by using the Netpbm format converters.
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 http://www.ivtools.org.
Ilib is a C subroutine library with functions for adding text to an image (as you might do at a higher level with pbmtext, pnmcomp, etc.). It works with Netpbm input and output. Find it at http://www.radix.net/~cknudsen/Ilib. Netpbm also includes character drawing functions in the libppm library, but they do not have as fancy font capabilities (see 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.
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 http://sourceforge.net/project/?group_id=1322.
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://www.colorado-research.com/~gourlay/software/Graphics/Xmorph.
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 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 http://altmark.nat.uni-magdeburg.de/~jschulen/ocr/.
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 pnmtopng/pngtopnm is at 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.
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. jpegtran comes with the Independent Jpeg Group’s (http://www.ijg.org) JPEG library.
Some tools to deal with EXIF files (see also Netpbm’s jpegtopnm and pnmtojpeg): To dump (interpret) an EXIF header: Exifdump ((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.
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 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).
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.