Raphael Linus Levien (also known as Raph Levien) is an influential member of the free software developer community, through his creation of the Advogato virtual community and his work with the free software branch of Ghostscript. Since 2007 he is employed at Google. He holds a PhD in Computer Science from UC Berkeley. He also made a computer-assisted proof system similar to Metamath: Ghilbert. In April 2016, Levien announced a text editor made as a "20% project" (Google allows some employees to spend 20% of their working hours developing their own projects): Xi.
The primary focus of Levien's work and research is in the varied areas regarding the theory of imaging—that is, rendering pictures and fonts for electronic display, which in addition to being aesthetically and mathematically important also contribute to the accessibility and search-openness of the web.
Levien has written several papers documenting his research in halftoning technology, which have been implemented in the Gimp-Print free software package, as well as by several commercial implementations. He also created Gill, the GNOME desktop illustration application which aimed at supporting the W3C SVG standard for Vector Graphics. He states it was named after Eric Gill, the English type designer responsible for the Gill Sans, Perpetua and Joanna fonts. Direct development on Gill ceased around the year 2000, but a fork of its codebase has evolved to Sodipodi, and through it to Inkscape.