Backup all pictures without iTunes
Connect the iPhone to a USB socket on your computer. The iPhone should prompt you to ask whether you trust the computer, click "Trust".

Depending how Windows (I'm assuming you are running Windows) is configured on your PC you might get an AutoPlay dialog that gives you a number of options including "Import pictures and videos".

If not then open "My Computer" (or "Computer" in more recent versions of Windows), where the iPhone should be listed as a device. If you right-click it there should be an option that says "Import pictures and videos".

You can find more detailed information here: http://www.wikihow.com/Transfer-Photos-from-an-iPhone-to-a-Computer