If you're talking about skipping the memory card and saving to harddisk directly then google tethered photo capture or check out this youtube video. Of course this is not a Processing issue, but much more related to your photo camera.

If you're talking about loading/using images in real-time (either from a camera or a directory) then this code may be helpful. Specifically the parts about checking a directory for new files and loading the images in case there are new ones. You could for example change the path to the directory (on the camera) where the photo's are saved.