That's why I said image proxy. External images are cached, so they must be known? I looked in the table 'xf_image_proxy' and it does not store the width and height :S. This shouldn't be too hard to make though. It would make for a really lazily loaded XenForo. I am thinking of making an addon for this. Any sort of gotcha's about the image proxy data? Does it guarantee a valid image? Is the mimetype always correct?