Tom Duff

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Thomas Douglas Selkirk Duff
Tom Duff in his office at Pixar
Born (1952-12-08) December 8, 1952 (age 70)
OccupationComputer programmer
Years active1974-2021
Known forAnimation software
Notable work

Thomas Douglas Selkirk Duff (born December 8, 1952) is a computer programmer.

Early life[edit]

Duff was born in Toronto, Ontario, Canada, and was named for his putative ancestor, the fifth Earl of Selkirk. He grew up in Toronto and Leaside. In 1974 he graduated from the University of Waterloo with a B.Math and, two years later, was awarded an M.Sc. from the University of Toronto.


Duff worked at the New York Institute of Technology Computer Graphics Lab and the Mark Williams Company in Chicago before moving to Lucasfilm's Computer Research and Development Division. He and Thomas Porter, another Lucasfilm employee, developed a new approach to compositing images; their 1984 paper, "Compositing Digital Images",[1] is "[t]he seminal work on an algebra for image compositing", according to Keith Packard.[2] and "Porter-Duff compositing" is now a key technique in computer graphics. (See, for example, XRender and Glitz.)

Duff later worked for 12 years at Bell Labs Computing Science Research Center, where he worked on computer graphics, wireless networking, and Plan 9;[3] in the course of his work there, he authored the well known "rc" shell for the Version 10 Unix operating system.

Duff worked at Pixar Animation Studios from 1996 until his retirement in 2021.[4]



  • Tom Duff makes a cameo appearance in the Niven/Pournelle science fiction novel Footfall as a co-discoverer of the invading spaceship: "Chap named Tom Duff, a computer type, spotted it."
  • Tom Duff appears briefly in the documentary film "Noisy People" (dir Tim Perkis, 2006) playing the banjo.[6]

See also[edit]


  1. ^ Porter, Thomas; Tom Duff (1984). "Compositing Digital Images". Computer Graphics. 18 (3): 253–259. doi:10.1145/800031.808606. ISBN 978-0-89791-138-2. S2CID 18663039.[permanent dead link]
    (Available at
  2. ^ Keith Packard's webpage about Porter & Duff's 1984 paper
  3. ^ "Shoot-out: Most annoying compiler error message | Lambda the Ultimate".
  4. ^ Duff, Tom [@TomDuff] (January 15, 2021). "Today, I'm retiring from Pixar, 40+ years after I first started. It's been a great run. Keep making the world's best movies #pixar" (Tweet) – via Twitter.
  5. ^ "Recipients of the J.W. Graham Medal in Computing & Innovation". University of Waterloo. Retrieved 2015-09-25.
  6. ^ "Noisy People: Improvising a Musical Life". Retrieved 2022-08-12.
  7. ^ N.J.A. Sloane, R.H. Hardin, T.S. Duff, J.H. Conway: "Minimal-Energy Clusters of Hard Spheres", Discrete & Computational Geometry 14, No. 3, 237–259, 1995.
  8. ^ J.H. Conway, H.T. Croft, P. Erdos, M.J.T. Guy: "On the Distribution of Values of Angles Determined by Coplanar Points", J. London Math. Soc., II., Ser. 19, 137–143, 1979.

External links[edit]