How are images stored on the hard drive of an iPhone? If I were to examine my iPhone's hard drive, in what format would I find the images in the Photos app stored?

Are they in a big .sqlite database file? Or are they stored as individual files such as .jpg?

I'm looking for the extension used (e.g. .sqlite, .png, .jgp, etc.).
All the images are stored as jpegs in various locations. The camera roll, for example, is stored in /private/var/mobile/Media/ (unless they've moved it).