Editing JPEG (section)

===Background===
The original JPEG specification published in 1992 implements processes from various earlier [[Academic paper|research papers]] and [[patent]]s cited by the [[CCITT]] (now [[ITU-T]]) and Joint Photographic Experts Group.<ref name="t81">{{cite web |title=T.81 – DIGITAL COMPRESSION AND CODING OF CONTINUOUS-TONE STILL IMAGES – REQUIREMENTS AND GUIDELINES |url=https://www.w3.org/Graphics/JPEG/itu-t81.pdf |publisher=[[CCITT]] |date=September 1992 |access-date=12 July 2019 |archive-date=30 December 2019 |archive-url=https://web.archive.org/web/20191230093239/http://www.w3.org/Graphics/JPEG/itu-t81.pdf |url-status=live }}</ref>

The basis for JPEG's [[lossy compression]] algorithm is the [[discrete cosine transform]] (DCT),<ref name="t812" /><ref name="heise3" /> which was first proposed by [[Nasir Ahmed (engineer)|Nasir Ahmed]] as an [[image compression]] technique in 1972.<ref name="Ahmed2">{{cite journal |last=Ahmed |first=Nasir |author-link=N. Ahmed |date=January 1991 |title=How I Came Up With the Discrete Cosine Transform |url=https://www.scribd.com/doc/52879771/DCT-History-How-I-Came-Up-with-the-Discrete-Cosine-Transform |journal=[[Digital Signal Processing (journal)|Digital Signal Processing]] |volume=1 |issue=1 |pages=4–5 |doi=10.1016/1051-2004(91)90086-Z}}</ref><ref name="heise3" /> Ahmed published the DCT algorithm with T. Natarajan and [[K. R. Rao]] in a 1974 paper,<ref name="pubDCT">{{Citation |last1=Ahmed |first1=Nasir |title=Discrete Cosine Transform |date=January 1974 |journal=IEEE Transactions on Computers |volume=C-23 |issue=1 |pages=90–93 |doi=10.1109/T-C.1974.223784 |s2cid=149806273 |last2=Natarajan |first2=T. |last3=Rao |first3=K. R. |author1-link=N. Ahmed |author3-link=K. R. Rao}}</ref> which is cited in the JPEG specification.<ref name="t812" />

The JPEG specification cites patents from several companies. The following patents provided the basis for its [[arithmetic coding]] algorithm.<ref name="t81"/>
* [[IBM]]
** {{US patent|4652856}} {{ndash}} February 4, 1986 {{ndash}} Kottappuram M. A. Mohiuddin and [[Jorma Rissanen|Jorma J. Rissanen]] {{ndash}} Multiplication-free multi-alphabet arithmetic code
** {{US patent|4905297}} {{ndash}} February 27, 1990 {{ndash}} G. Langdon, [[Joan L. Mitchell|J. L. Mitchell]], W. B. Pennebaker, and Jorma J. Rissanen {{ndash}} Arithmetic coding encoder and decoder system
** {{US patent|4935882}} {{ndash}} June 19, 1990 {{ndash}} W. B. Pennebaker and J. L. Mitchell {{ndash}} Probability adaptation for arithmetic coders
* [[Mitsubishi Electric]]
** {{Patent|JP|H02202267}} ([https://patents.google.com/patent/JPH02202267A 1021672]) {{ndash}} January 21, 1989 {{ndash}} Toshihiro Kimura, Shigenori Kino, Fumitaka Ono, Masayuki Yoshida {{ndash}} Coding system
** {{Patent|JP|H03247123}} ([https://patents.google.com/patent/JPH0834434B2/en 2-46275]) {{ndash}} February 26, 1990 {{ndash}} Tomohiro Kimura, Shigenori Kino, Fumitaka Ono, and Masayuki Yoshida {{ndash}} Coding apparatus and coding method

The JPEG specification also cites three other patents from IBM. Other companies cited as patent holders include [[AT&T]] (two patents) and [[Canon Inc.]]<ref name="t81"/> Absent from the list is {{US patent|4698672}}, filed by [[Compression Labs, Inc.|Compression Labs]]' Wen-Hsiung Chen and Daniel J. Klenke in October 1986. The patent describes a DCT-based image compression algorithm, and would later be a cause of controversy in 2002 (see ''[[#Patent controversy|Patent controversy]]'' below).<ref name="cnet">{{cite news |last1=Lemos |first1=Robert |title=Finding patent truth in JPEG claim |url=https://www.cnet.com/news/finding-patent-truth-in-jpeg-claim/ |access-date=13 July 2019 |work=[[CNET]] |date=23 July 2002 |archive-date=13 July 2019 |archive-url=https://web.archive.org/web/20190713165715/https://www.cnet.com/news/finding-patent-truth-in-jpeg-claim/ |url-status=live }}</ref> However, the JPEG specification did cite two earlier research papers by Wen-Hsiung Chen, published in 1977 and 1984.<ref name="t81"/>