Example of processing a file upload?

Is the source code for the Image Trace app available? Or is there an example anywhere of processing a file upload? I’m trying to figure out how to get image data from the URL that the file picker returns, but without access to the DOM (and thus canvas), I’m hitting a brick wall.

I would check here Inventables · GitHub and see if I could find what I needed.

Thanks. In the vectorize example, I found that the image processing is offloaded to a remote server, so I guess I’ll do that.