Simple answer is no if this needs to be done on client side. The canvas element is the only way to convert an image to bitmap data or data-uris (and even then security restriction may apply preventing this).
You can maybe get around this using Flash but of course that would require the client to have Flash installed.
Or setting up an external web service where you can upload the image and have it return the data you need.
For IE8 and lower there are no options out of the box (exCanvas gives you canvas drawing capabilities but can't provide bitmap data which is needed here). Basically, for IE8 you will need a server.