Pixastic.js
I have been playing around with the pixastic.js javascript image manipulation library lately and really enjoying the results. The need for an image manipulation library arose when I needed some image effects to happen dynamically on the Imajin Products homepage that I am currently developing.
I needed some way of dynamically putting a grayscale filter on an image on hover over and I was up in the air between processing.js and pixastic.js. I decided on pixastics.js because I read somewhere that processing.js was not specifically designed for image manipulation and I figured I would go with the more specialized one because I figured would have more image effects and be more efficient.
So far it has turned out to be very simple to use, and the documentation is very easy to read and follow. Definitely been a good choice.