Limit signature size?

[LudiusMAX]

This user has been denied support.

I want to limit the dimensions of signatures. All of the plugins I use don't work. I want the forum to automatically give an error if a user tries to upload a signature that's too big.

[effone]

Well, instead of throwing an error you can shrink it like this:
http://community.mybb.com/thread-149240.html