I wonder if is there any way I can get pixel data for the currently drawn path in the canvas tag.

I can calculate the pixel data on my own when drawing simple shapes like square or a line, but things get messy with more complicated shapes like ellipse or even a simple circle.

The reason i'm asking this is because I'm working on a web application which involves sending canvas pixels data to the server when I add a path to the canvas. The server needs to keep it's own copy of the entire canvas, and I really don't want to send the ENTIRE canvas image every single change, but only the delta for efficiency reasons...

Thanks.