Tom Duff

Thomas Douglas Selkirk Duff (born December 8, 1952) is a computer programmer.
Early life.
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.
Career.
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", is "[t]he seminal work on an algebra for image compositing", according to Keith Packard. 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; 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.