Data compression in general

• US 5016009 – (Main article: Stac Electronics)
• US 4701745 – also granted as GB 2172127^[12] - now expired

Stac Electronics sued Microsoft for patent infringement when Microsoft introduced the DoubleSpace data compression scheme into MS-DOS.^[13] Stac was awarded $120 million by a jury in 1994 and Microsoft was ordered to recall versions of MS-DOS with the infringing technology.^[14]

Audio compression

• US 5579430 – (Main article: MP3)

One of several^[15] patents covering the MP3 format owned by the Fraunhofer Society which led to the development of the Ogg Vorbis format as an alternative to MP3.^[16]

• US 5627938 – (Main article: Alcatel-Lucent v. Microsoft)
• US 5341457

Two patents owned by Alcatel-Lucent relating to MP3 technology under which they sued Microsoft for $1.5 billion.^[17] Microsoft thought they had already licensed the technology from Fraunhofer, and this case illustrates one of the basic principles of patents that a license does not necessarily permit the licensee to work the technology, but merely prevents the licensee from being sued by the licensor.^[18]

Image compression

• US 4558302 (Main article: GIF)
• EP 0129439

Unisys's patent on LZW compression, a fundamental part of the widely used GIF graphics format.

• US 4698672 and its EP equivalent EP 0266049
• (Main article: Forgent Networks)

Forgent Networks claimed this patent, granted in 1987, covered the JPEG image compression format. The broadest claims of the US patent were found to be invalid in 2005 following re-examination by the US Patent and Trademark Office.^[19]

• US 5710835
• EP 0864135

This article needs to be updated. (November 2010)

This patent, owned by Lizardtech, Inc., was the subject of infringement proceedings against companies including Earth Resource Mapping, Inc. However, Lizardtech lost the trial on the grounds that an important part of their invention was the step of "maintaining updated sums of discrete wavelet transform coefficients from the discrete tile image to form a seamless discrete wavelet transform of the image". Claim 21 of the patent lacked this feature and was therefore obvious. The remaining claims contained this feature, but were not infringed by ERM.^[20] Internet buzz suggested the patent covered the JPEG 2000 image compression format but the additional feature of the valid claims appears not to be a JPEG 2000 requirement.^[21]

Video compression

Notable due to proprietor hyperbole

• US 5241671

Owned at various times by Encyclopædia Britannica, Inc. and Compton's NewMedia, Inc. this patent was granted in August 1993. Just a few months later, in November 1993, Compton's announced that "Everything that is now multimedia and computer-based utilizes this invention" and tried to use the patent to ensure that everyone licensed their software.^[35] Although a cursory review of the granted claims showed this statement to be mere hyperbole, there was nonetheless an outcry from the industry and the patent was revoked following re-examination.^[36]

• US 5842213 and US 6393426

Patents owned by Scientigo and claimed by them to cover the markup language XML, a notion rejected by patent attorneys and other commentators including Microsoft.^[37]

Notable due to misconception

• US application 2006015812 – Emoticon keyboard button patent application.
• EP application 1784745

Early in 2006, rumours circulated on the Internet that Cingular Wireless had patented the emoticon and, in particular, had patented the concept of using emoticons on mobile phones.^[38] This resulted in a great deal of anger directed at the US Patent Office that such patents should never have been granted.^[39] Ultimately, it was pointed out that it was only a published patent application, not a granted patent, and that the claims of the patent application actually related to a mobile phone with a dedicated button for inserting emoticons.^[40]

This patent application is currently being examined by the US patent office. All of the originally filed claims were rejected on 22 February 2007 as being known or obvious, although the rejection was not final.^[41] Examination of the corresponding European patent application also suggested that the claims lacked an inventive step, and the application lapsed in 2010.^[42]

• US D599372

This design patent was granted to Google on 1 September 2009 for the simple and clean appearance of their homepage from five years earlier.^[43] Referred to in the media as a patent, it received criticism for not being as original as Google's web search technology^[43] and was held up as evidence that the US patent system was broken.^[44] The New York Post said that Google now had the right to sue anyone who used a similarly no-frills website.^[43] However, a "design patent" is not the same as a "patent" (sometimes referred to as a "utility patent") since it provides only limited protection for ornamental appearance.^[45] Design patents are typically hard to infringe^[46] and even Google's own homepage at the time the design patent was granted was almost certainly different enough from the design patent that it did not infringe it.^[45][46]