I once worked on a project moving TIFF images (scanned passports and other id docs) stored as BLOBs in an Oracle database to the file system. We did run into performance problems and moving them out solved things. I don't know the limits of mySQL but I think sooner or later you will run into performance problems as well. In the end the file system gives better performance (scales better). You have many small images, so some clever tree structure to quickly locate an image is needed. Many little files in one directory is normally an OS-killer. There are also dedicated image databases around which do a good job.