I think, it could be possible to make this password protection for yourself: the first tip is, to use a name with another meaning, maybe pict1.jpg. Only your program knows, whats inside. But it could be, that some search routines want to catalog each picture?!
The second idea: protect the first block of the database with an logical Xor Bit system; only you know, how to reverse it. The problem could be, if something is crashing, the database stays unprotected...