Many composite operations are wrong:
http://www.html5canvastutorials.com/advanced/html5-canvas-global-composite-operations-tutorial/
(note that FF disagrees with Chrome on the effect of Copy and I think that Chrome is right in this case...)
http://www.html5canvastutorials.com/advanced/html5-canvas-global-composite-operations-tutorial/
(note that FF disagrees with Chrome on the effect of Copy and I think that Chrome is right in this case...)