THis is for techies only.

I come from a IIS/ASP/.NET background and have NEVER touched PHP. We have just got a contract in to build a site, but it has to be in PHP. Having taken a quick look at it i can't really see it being too much of a problem. However i am in need of a component that does the following:

When a user uploads a JPG via a web browser i require it to resize the image then resave it as a JPG. Other features such as crop/rotate would be an advantage.

Any ideas of good PHP component libraries?

Cheers in advance.