<object type=”image/svg+xml” data=”example.svg”> <object type=”image/png+300dpi” data=”example-hi.png> <img src=”example-low.png” /> </object> </object>

It would make more sense to use something akin to the existing encoding definition: Content-Type: text/plain Content-Type: text/html; charset=utf-8 Applied to images: Content-Type: image/png; dpi=72 Content-Type: image/png; dpi=96 Content-Type: image/png; dpi=300 Content-Type: image/tiff; dpi=72,96,300 (noting that TIFF files can contain multiple resolutions) Browsers could then send: Accept: image/png; dpi=120 and the webserver would return the image with the same or next higher DPI (the 300 in this case). I thought inches had been replaced by centimetres anyway? - Nicholas.