Partinen made the announcement on Twitter, saying that Friday was his last day at Nokia and that he would soon "start a new chapter in Cupertino, California." The tweets were first noticed by Engadget.
According to his LinkedIn profile, Partinen leaves Nokia as the company's Lumia Photography Lead "in the fields of mobile photography, image quality verification, verification up-streaming, 3rd party management and collaboration, supplier collaboration and technical marketing in various multimedia segments." Products for which he was responsible include the Nokia 808 PureView and Nokia N8.
A graduate of Helsinki University of Technology, Partinen joined Nokia as an image quality engineer in 2007. He is credited as one of the inventors of Nokia's PureView system, which is widely lauded by photography enthusiasts as among the best mobile camera technologies available.
PureView uses pixel oversampling and on-chip image processing to shrink a very large image -- the Nokia Lumia 1020 ships with a 41-megapixel camera -- into a smaller, higher-quality one. This allows for sharper images, enhanced digital zoom capability, and better low-light performance.