There isn't a limit on image uploads for registered accounts. The limit is how many of your own uploads you can see. Last time I checked, all uploads beyond 225 won't be displayed. In order to see them, you have to delete others. They all still exist and are marked up on your account, but they force you to clear newer images to even see older ones you might not even want.
That's why I still use Photobucket and ImageShack, and usually upload images without being logged in on Imgur. They are richards about storage space. Uploading on your account basically does "You can see the last 225 files you've uploaded" while logged out, you have to manually keep track. Dumb.