Currently, we can prevent thee user to upload an image too big(in MB), but not define a limit width and height.
This function can be useful on his own, but also it would help to resolve an issue.
When you tried to upload a very big file : 13000*9000px and to re-size it, flash cant' do that because of the total memory needed.(around 550MB).
But the problem is that my file is just 2.9MB.
I think it would be good to able us to set limits on with / height.
Flash can't handle images bigger then 8191x8191. It's not a memory issue, but rather an inner constraint. We now handle this properly and trigger an error. Filter on image size is great idea. Need to think a bit how to add this.
+1 on needing a filter for a minimum / maximum image size
Anything ever come out this? Would be a great feature!
I doubt we will ever put this into the core, but here's how you could try something like this yourself: max_img_resolution