local html files can not use canvas.toDataURL() & canvas.getImageData() see http://stackoverflow.com/questions/10187306/canvas-todataurl-throws-security-exception-despite-image-being-local and http://stackoverflow.com/questions/6710393/canvas-getimagedata-after-drawing-image-from-file-uri-need-workaround-for
local html files can not use canvas.toDataURL() & canvas.getImageData()
see
http://stackoverflow.com/questions/10187306/canvas-todataurl-throws-security-exception-despite-image-being-local
and
http://stackoverflow.com/questions/6710393/canvas-getimagedata-after-drawing-image-from-file-uri-need-workaround-for