Image size and resolution

Hi, how could I put a limit to the maximum image size to upload as well as the maximum allowed resolution.

I've tried with the filemanager module settings, the image module settings, the file uploads module settings and nothing. As for the Acidfree settings there aren't fields that manage the maximum size and resolution of the images.

So, what can I do in order to avoid having my users uploading monster images with sizes of over 512KB.

Any help appreciated,
thank you in advance.

Greg