I can't tell if you're being sarcastic or not, so I'll give you the benefit of the doubt.

Yes I mean in the browser. The convolution (edge-detection) is definitely possible in WebGL, and the dynamic programming algorithm probably is, so you could probably get sufficient performance in the browser to do this on multiple images in real time.

Not sarcastic. I just didn't know whether you meant the browser or eg the last layer of, say, PHP before it leaves the server.