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+Netpbm consists of code contributed by many authors.  In most of the
+source code files, there is a copyright notice and license, telling
+you what you may or may not do with the code.  All authors have granted
+you the right to use and distribute their code without having to pay
+them, as long as you meet some simple requirements.
+
+Most of the components require you to include a copy of their
+copyright notices and warranty disclaimers in any copies or
+derivations you distribute.
+
+Another restriction that some of the software has is that in order to
+have permission to copy it (which includes writing anything derived
+from it), you must distribute source code for your copy or derivation
+and propagate the same restriction to people who would copy your
+derivation.  In other words, the price the author wants for the use of
+his proprietary work is your contribution to the free software cause.
+
+One component prohibits you from selling it or using it in a
+commercial way: hpcdtoppm.
+
+Some components are contributed to the public domain.  
+
+The copyrights on individual components of this package are detailed 
+at appropriate places within the package.  A slightly out of date
+summary of all the copyrights is in the file 'doc/copyright_summary'
+in the Netpbm source tree.
+
+As with most public open source software, no one really knows for sure
+where the code came from.  It is possible that a contributor copied it
+without license to do so.  That might mean any user of the code owes
+someone royalties.  The Netpbm maintainer in particular has received
+no warranties regarding any of the code in the package.  So consider
+all the above to be modified by "to the best of the Netpbm
+maintainer's knowledge."
+
+
+
+PATENTS
+-------
+
+These are the patents the Netpbm maintainer knows about that relate to
+Netpbm.  It is basically just information the maintainer has stumbled
+over at some point -- no search has been done.
+
+No licenses have been granted by patent owners to the maintainer of
+Netpbm.  Therefore, if you need a patent to use something in Netpbm,
+you need your own license.
+
+A note about patents in general: A patent gives an inventor the
+exclusive right to make, sell, or use the invention.  If you
+independently invent something without knowing that the patent holder
+already did, that makes no difference -- the patent holder still has
+the exclusive right.  It makes no difference if you give the original
+inventor credit.  The patent applies to a method, not its expression,
+so writing a program from scratch to implement a certain method is
+still a patent infringement.  Infringing a patent is not a crime per
+se, but to the extent that it costs the patent holder money, the
+infringer has to make it up.
+
+The original purpose of patents is probably perverted when patents are
+applied to things you implement in computer programs.  This is one of
+the Free Software Foundation's causes.  See 
+<http://www.gnu.org/philosophy.html#laws>.
+
+
+Unisys owns patents on LZW compression, which is used by Ppmtogif, and
+maybe on LZW decompression, which is used by Giftopnm.  IBM also owns
+a patent that may cover the GIF tools.  Unisys offers a license of the
+patent for trivial use for $5000.  Its U.S. patent (Number 4,558,302)
+EXPIRED June 20, 2003.  In most of Europe, the patent expires June 18,
+2004.  In Japan, it's June 20, 2004 and in Canada, July 7, 2004.
+IBM's U.S. patent expirs August 11, 2006.
+
+Neither company has ever enforced the patent against trivial users of
+it.  <http://news.cnet.com/news/0-1005-200-1713278.html> is an article
+dated April 18, 2000 on the issue.
+http://www.unisys.com/about__unisys/lzw/> is Unisys' view of the
+matter.  For information from another perspective, see
+<http://burnallgifs.org>.
+
+The following Netpbm components may be restricted by these patents:
+Ppmtogif, Giftopnm.
+
+A good substitute for GIF if the patents are a problem is PNG (see
+pngtopnm, pnmtopng), which was developed with a primary purpose of not
+using any patented technology.
+
+You can also use the -nolzw option on ppmtogif to avoid using the LZW
+patent.  The images so generated are larger than traditional
+LZW-compressed GIFs, but any GIF decoder can decode them just the
+same.
+
+I repeat: The Unisys U.S. patent has expired.  It is not an issue
+for any future use of Netpbm.
+
+
+The Pnmtojpeg and possibly Jpegtopnm programs in some cases may use
+the arithmetic coding patents owned by IBM, AT&T, and Mitsubishi.
+There is difference of opinion on whether they do.
+
+Forgent owns a patent it believes covers JPEG compression.  This
+patent was virtually unknown before July 2002, when Forgent began to
+enforce it.  It has successfully enforced it against two companies
+(Sony and an unnamed Japanese digital camera maker), but without court
+ruling.  This patent, U.S. Patent No. 4,698,672, expires in 2006.
+
+Philips and Lucent Technologies also own patents they claim cover
+JPEG.
+
+The following Netpbm components may be restricted by these patents:
+Jpegtopnm, Pnmtojpeg, Ppmtompeg, Tifftopnm, Pnmtotiff.  These all
+do their JPEG work via a JPEG library not distributed with Netpbm.
+Your JPEG-related liability for using Netpbm is limited to your 
+liability for using your JPEG library.
+
+The next best alternative to JPEG is probably PNG and maybe JBIG for
+bilevel (black and white) images.
+
+http://burnalljpegs.org contains information on this issue.
+
+
+The Jbigtopnm and Pnmtojbig programs use arithmetic coding patents and
+other patents covering various aspects of the "front end."
+
+