Great stuff. Two things I would add in the readme to make it easy to run locally

[ndvbd]

So to run locally (via filesystem, with no server), you should do two things:

1. in main.js after image.src, do image.crossOrigin = "anonymous";

2. Run the browser with no security, for example for chrome do:
   chrome.exe --disable-web-security --allow-file-access-from-files