Ashley Why didn't you add an option to select pictures in hard drive instead of use camera?
According to example 5, ignore upload function, just draw on canvas in client-side:
http://dev.w3.org/2009/dap/camera/
Using File API, it's now compatible in most browsers for mobile devices, http://caniuse.com/fileapi
Node-webkit is other story, only for desktops but useful to write and read external files without permission.