A database is meant to store searchable data.
Blobs in the shape of images are not searchable,
so all you are doing is creating a very fancy filesystem.
In short, you are creating overhead.
If you are just storing images, then the filesystem itself is probably the fastest possible means.
I would recommend just using the database to hold the pathname to the file so you can still automate adding/deleting of files, but you're not giving the database server extra load.
Apart from that, MySQL works with cooked files to hold it's database data. That means al your blobs are appended into one big file.
