Can you import pictures from a locked iPhone with image capture?
Do you have access to the computer that syncs this device? If so, it will allow you to reset the passcode (and/or import the pictures without needing to unlock the iOS device.).

If not, you either have to crack the passcode or enter it properly. As there is a penalty for guessing wrongly (and perhaps a wipe after X incorrect guesses option that could be enabled), it's best to get help from someone who has knowledge of how passcodes (and tools to bypass them) work if the pictures are of value to preserve.