Just as a guess, you could use ObjectMemorySerializer.save() to save a serialized image to the CRIO's memory, then FTP to get it and find a way to convert it from a desktop setting. I'm sure you aren't talking about converting it onboard the computer right? You wouldn't be opening ms paint during competition.
As to how to convert it, you could use a java library that allows you to construct jpeg/bmp/png/gif/etc using pure data and use the wpilibj.jar to access the serialized object you saved. Probably a complex answer, but I've never done it so I don't know a better way.