Before you dive into this area, it is helpful to visit Dan Bricklin's web site for a discussion of Patent Law and Software. Today, many people seem to think Microsoft invented the spreadsheet (Excel). Of course, Dan was one of the inventors of Visicalc, the first electronic spreadsheet. His company did not patent that invention (based on a lawyer's advice that they "had a 10% shot at being successful"). You can learn why and how the use of patents with software affects current developers and users. Visit his site here. This continues to be a controversial subject.

Visit IBM's very useful patent web site and review two patents:

US05185667 | US05877801

Patents Reversed:
One writer mentioned Compton's mid 1980's claim to have invented multimedia as an example of erroneous patents. This patent was reversed in 1994. Learn more at the following sites:

Compton Patent: Subject: Compton Patent Reversed (details)
http://cuiwww.unige.ch/OSG/info/MultimediaInfo/Info/compton.html

Compton Patent: PTO Commissioner Initiates Reexamination
http://www.ljextra.com/misc/brw/2f3.html

Compton Patent: Multimedia Patent Battle Heats Up
http://www.library.ubc.ca/patscan/compton.html

Patent Law Materials
http://www.law.cornell.edu/topics/patent.html

US Patent and Trademark Office
http://www.uspto.gov/

U.S. PATENT ACT
§ 301. Citation of prior art § 302. Request for reexamination
http://www2.law.cornell.edu/cgi-bin/foliocgi.exe/patentact/query=[jump!3A!2735uscs301!27]/doc/{@376}/words=4?

What's the Difference? Comparing Patent and Copyright Protection for Software
http://www.mccutchen.com/ip/ip_2101.htm
Prior Art

There has been an extensive discussion over the years of work that preceeded these patents or "Prior Art".

Dan Slater elaborated recently on this issue:

I was really quite stunned to hear of low class harassment of Helmut
Dersch by the IPIX lawyers. Helmut has been one of the most imaginative,
generous and creative members of the panoramic imaging and VR community.
His development of Panorama Tools showed many that high quality image
warping was possible. He gave this program freely to the panoramic / VR
community. His other invention of micropanoramic imaging methods has
been an inspiration to other of my own work.

In the past, IPIX (then Omniview) had queried me for technical details
about my own fisheye lens based Spherecam system (
http://www.nearfield.com/spherecam/ ). They found it quite interesting
and were interested in building one of their own. Back then, I gladly
sent them detailed photos and sample images for them to process, in
addition to answering a variety of technical questions. I believe that
they have since built both still and video versions of this. Later when
they changed management and became IPIX, there seemed to be a major
shift in philosophy. They have become quite litigious and have
successfully sued and/or threatened a number of companies including
Infinite Pictures, Live Picture and apparently others. With their legal
attack on Helmut it appears that this continues to remain their business
philosophy. I obviously regret the help I gave them way back when. IPIX
seems to be a company that only takes but never gives.

I believe that their prior lawsuits and threats against others were
centered around their patents. IPIX US patents include: 5,313,306,
5,185,667, and at least two others. Some of their claims are quite
broad, suggesting that any geometric remapping of a fisheye image is
their invention. There is considerable prior art that would seem to
invalidate these broad IPIX claims. Variations of fisheye image
geometric remapping type systems have been used in aerospace, aerial
photography, submarine periscopes, flight simulation, planetarium
projection, etc. As an example, one system from the early 1970,s used a
6 mm Nikon fisheye lens in a F-111 aircraft to view wing extension
simultaneously on both sides of the aircraft while also providing star
image data. Two particularly relevant prior art references that would
appear to completely invalidate the broad IPIX patent claims include:

Ripley, D., DVI - A Digital Multimedia Technology, Communications of the
ACM, Volume 32 Number 7 (July 1989)

This paper describes an interactive computer based system that
dynamically extracts perspective corrected views from images filmed with
a Nikon 220° fisheye lens.

Lippman, A., Movie Maps: An Application of the Optical Video Disc to
Computer Graphics, Siggraph Conference Proceedings (1980)

This second paper describes an early VR system that used either a set of
4 cameras or a single donut image camera that captured the complete road
system in a small town. The viewer could travel down any of the roads in
several different seasons and see perspective corrected views. The
single camera system could use either the Nikon 6 mm f2.8 fisheye lens
or the Kern Peri Apollar lens to record a full 360 degree horizontal
view.

Ripley (the author of the 1st paper) is a principle of Infinite Pictures
that was sued by IPIX for patent infringment and lost with a million
dollar judgement against him. To this day, I don't understand why, as
both of these papers clearly describe prior art of undistorting fisheye
images to extract "perspective corrected" views, etc.

>From reading the letters that Helmut posted on his web site, it is quite
apparent that the IPIX lawyers are interested in harassing him. If they
are accusing him of copyright infringment, why would they want him to
eliminate PanTools, the PanTools FAQ, etc. The IPIX file format is
proprietary and unpublished but PanTools does not use it in any way
whatsoever so there can not be an issue here. I don,t know the IPIX
patent status in Germany but I would guess that it is not patented
there. My guess is that IPIX does not like that Helmut,s Pan Tools can
do high quality geometric image processing of fisheye images so they are
harassing him in a 3rd country (England) via these other charges.

Maybe next IPIX will go after Adobe Photoshop, followed by map making in
general. Map makers have been warping fisheye (f theta) and other
distorted images of the Earth to many other image formats for centuries.

I really wish Helmut the best of luck and hope that he continues with
his excellent ideas and software.

Dan Slater (dslater@ix.netcom.com)