I don't see how LDing could help build a photographic memory.

HOWEVER.

through the use of associative and mnemonical techniques, such as that outlined by Chatter-Box, you can expand your capacity to memorise things.

Another note: If you're trying to study for a test, never try to memorise more than SEVEN (7) things at once. There's a detailed explanation behind that, but, trust me. This is why phone numbers (excluding extensions) are usually 7 or less digits, why numberplates (usually) are 7 or less digits, etc.