Its never a good idea to store binary data in your database, take a look at this post: https://stackoverflow.com/questions/662488/would-you-store-binary-data-in-database-or-in-file-system and this post: https://stackoverflow.com/questions/5778380/why-store-binary-data-in-mysql
In my opinion, its far faster to use the file system and here’s why:
The image URL can be stored in a custom field by wordpress – this is very simple to do.
The same representation of that image stored as binary is far larger than the image URL, therefore somewhat slower to fetch. You would also have to specifically write the code to do this. Its not native to wordpress.