Zwei interessante Canvas Bibliotheken sind mir heute über den Weg gelaufen. Da ist zum einen PaintbrushJS
PaintbrushJS is a lightweight, browser-based image processing library that can apply various visual filters to images within a web page.
You use it by applying a class to an element on the page and setting a few parameters with some extra HTML attributes. If the element is an img or it has a background-image set in your CSS, PaintbrushJS will create a temporary canvas element and manipulate the image there, before finally saving it back out to the original element.
und zum anderen CamanJS
CamanJS is very easy to extend with new filters and plugins, and it comes with a wide array of image editing functionality, which is only growing as the community makes more plugins. It has a powerful layering system, much like the one present in Photoshop and GIMP, that makes the sky the limit for your creativity.