This idea has been developed and deployed to Canvas
As a tablet user, the Teacher app is a great way to quickly go back and forth with student assignments. Currently, the app does not support annotations on image files like jpegs. For math/science/art teachers, it would be great for students to be able to work problems out on paper, use their Student app to upload a quick image, and get written feedback without turning in a huge pile of papers/projects to their teacher. As a teacher, it would be amazing to not have to carry around huge stacks of papers to grade everywhere, and have them all in my Teacher app ready to go. I know that I can annotate images on a computer, but it's so much easier with a stylus on my tablet than drawing with a mouse or typing.
I also know that annotations can be done on the Teacher app with doc files and PDFs, but I don't want my students to have to change every image into a PDF before they turn it in. Unless the Student app is going to do that for them, that is.
Canvas has so many great qualities! Let's open up ONE MORE avenue for the paperless classroom to be hassle-free.