I've got a page that builds a QR Code in the Canvas element at 256X256. The assigns the source of a corresponding 'blank' image tag to it's content with a canvas toDataURL() call. 

The client wants the image to be 156X156px when they save it to their machine. However when you right click to save as it saves it using the natural resolution (256X256) of the image and not the one defined the by Image tag. 

How do I scale it down or force the browser to save it at certain dimensions using JavaScript? 

Setting the width or height of the canvas just before I make it a URL seems to break the canvas and the image comes out as just white space.