“Camera Roll” aka pictures you take with your iPhone.

support.apple.com...

Summary
Pictures and screenshots taken with the iPhone are stored on the Camera Roll. When you sync or perform a restore, iTunes creates a backup the contents of your iPhone, including the Camera Roll. The more pictures or other multimedia files that are on the Camera Roll, the longer a backup or restore will take.

Just a warning to iPhone users that use the built in camera. Your pictures that are stored in the category “camera roll” on your iPhone ARE NOT BACKED UP when you perform a sync using iTunes. Even the “back up” in iTunes does not back up the camera roll.

Only way to get iTunes to do anything with them is import them to the PC and make sure whatever folder you imported to is selected to sync with iTunes.
I am sure that if you are running a apple product it is different story but the above applies to PC users. If I am wrong and somebody knows how to find the camera roll pictures hidden in the bowels of an apple backup database, I am all ears.

I know the above apple knowledge base article actually has the solution if you are proactive enough to import. Of course a client was not and learned the hard way after loosing his phone.