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. You can check out PaintbrushJS in action here.
Requirements: Does not work in IE8 or lower
License: MIT License