Image Processing with HTML 5

I wonder what are the possibilities to have some sort of image processing done in HTML5/JavaScript. I know that most of the image processing stuffs are resource-intensive, and better to be done in the client side. But what are the possibilities, if we consider the bandwidth aspects? How about something like this: we need some information of color usage and edges data of an image composed by the user. I think that if we upload the whole image to the server just to get only the needed data, it will not be cost-effective with the bandwidth aspects. Instead, is there any possibilities to have some sort of image processing done in the client side, and send only the retrieved data to the server?

The possibilities for HTML 5 to do this are pretty huge ... it's just a question of how the browser supports it.

The canvas element in HTML 5 is probably just what you are looking for.

Thanks Pete; and yes, canvas seems to be the place to start.
But is there a way for identifying the existing points of a drawn image on a canvas, so we can use them for some sort of image processing with JavaScripts?

You can do some pixel manipulation at the canvas level on RGBA values I believe, you can also do processing with WebGL shaders, there's a project called glfx.js that uses WebGL shaders to create various effects. http://evanw.github.com/glfx.js/