TMX -
1) how does it take less bandwidth, that doesn't even make any sense?
2) sotring them in the database means that the dynamic pictures will be backed up by the same routines that backup the rest of the database which makes for less coding and testing.
3) storing them in the database means that php doesn't need write access to a folder which leads to security issues.
4) if the picture are dynamic then they are data. Why wouldn't you store all your data in the database?