Joan L. Mitchell
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Joan L. Mitchell | |
|---|---|
 A JPEG picture of Joan L. Mitchell | |
| Born | May 24, 1947 Modesto, California, U.S. |
| Died | December 2, 2015 (aged 68) |
| Alma mater | Stanford University, University of Illinois at Urbana–Champaign |
| Known for | Co-inventor of JPEG digital image format. |
| Relatives | Eulalia Richardson Mitchell (grandmother, Physicist) |
Joan Laverne Mitchell (May 24, 1947 – December 2, 2015)[1][2] was an American computer scientist, data compression pioneer, and inventor who, as a researcher at IBM, co-invented the JPEG digital image format.[3]
Mitchell was born on May 24, 1947, in Modesto, California. Mitchell's father was William Mitchell and her mother was Doris Mitchell.[2]
Education
Mitchell was a National Merit Scholar at Stanford University, where her work included an independent study project on Brillouin scattering in bromine.[1] In 1969, Mitchell graduated with a Bachelor of Science degree in physics from Stanford University[1][4] with distinction[5] and Phi Beta Kappa.[1] She followed in the footsteps of her grandmother, Eulalia Richardson Mitchell, who also earned Stanford physics degrees in 1910 and 1912.[1][6]
Mitchell went on to graduate study in condensed matter physics at the University of Illinois at Urbana–Champaign, and earned a master's degree in 1971 and a Ph.D. in 1974 there.[1][3][4] As part of her Ph.D. work, she also learned computer programming, so that she could use a computer to solve the differential equations arising in her research.[1] Her dissertation, Effect of heterovalent impurities co-diffusing with monovalent tracers in ionic crystals, was supervised by David Lazarus.[7]
Career and later life
Mitchell began working at the IBM Thomas J. Watson Research Center in 1974, in the Exploratory Printing Technologies Group.[3][4] There, her inventions included a method for ultrasonic printing, a method for thermal-transfer printing later used in some models of the IBM Selectric typewriter, data compression for fax machines, a teleconferencing system,[3] and the Q-coder method for arithmetic coding used in JBIG image compression.[1] From 1987 to 1994, Mitchell helped develop the JPEG standard, and she became a co-author with Bill Pennebaker of the first book on the standard.[1][3][4] Gregory K. Wallace, another member of the group, remembers Mitchell and Pennebaker as "two of the most insightful, energetic, and prolific members" of the Joint Photographic Experts Group.[8]
During the mid-1990s Mitchell moved from the Watson Research Center to a different IBM group in Vermont and then (after a short leave as a visiting professor at the University of Illinois) to IBM's Printing Systems Division in Colorado.[3][4] In 2007 IBM sold their Printing Systems Division to Ricoh,[9] and Mitchell went with them to the resulting joint venture, InfoPrint Solutions. She retired in 2009,[10] and died on December 2, 2015.[2]
