PHP advanced graphics library

I'm developing a graphic manipulation web service in PHP, I want to accept images, apply filters and output them instantly. Is there any library out there to accomplish this task?

(think of filters like the ones used开发者_如何学编程 in this app http://www.toon-fx.com/toonpaint/)

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this link contains examples how to create and apply filters. It uses GD library. How To Create and Apply Image Filters in PHP

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Supporting Gordon's comment, you should check out PaintbrushJS.

http://mezzoblue.github.com/PaintbrushJS/demo/