I don’t know, but Innodb is pretty fast and definitely supports big drops. If you are looking to place images in a database, I suggest you just try and see how this happens.
I can tell you where people end up in your situation, is to set up a separate file system to store large drops (images in your case) outside the database, using a database to store metadata for these files. Drop your question about performance, it comes down to a question of cost. Database servers are expensive and important: filling them with large amounts of data that cannot be requested (not to mention indexing) is simply not a win.