In the photography world, a prominent proprietary file format is Kodak's Photo CD (.PCD). Once the premiere format for film scanning, it is now a difficult-to-work-around relic. Recently I set out to resurrect some old PCD images on a Linux system -- a challenge that serves as an object lesson in the importance of open standards in any kind of digital archive.
For years PCD was the preferred target format for professional photo labs scanning slides and negatives. It was the output of high-end, all-in-one scanning systems built by Kodak, supporting all types of film from APS size up to large-format.