Never re-size a thumbnail again
The guys at Garralab created NailThumb for us.
Create thumbnails easily from high-res images, without any distortion, with one line of code.
You can even decide thumbnail dimensions directly from CSS.
Integrates perfectly with any media gallery, even more useful in dynamic web application when you can face any shape or size.
If you want to add avatars to your application it’s easier to use this plugin to let them fit any size you need then to develop a functionality that help your user to upload avatars of the right size/sizes.
Whatever method you choose and whatever proportions limit you fix NailThumb will always create a thumbnail without any distortion and will keep your image as big as possible.