@squadette: pick a portrait-oriented photo from Google photos (quite large in my case), make sure it's accessible for those with the link, right-click and copy the URL of the image, go to Mokum, add URL, paste. Result: a landscape picture that contains the top part part of the original. See my other post for the full picture.
that's what Google Plus does to image pages (see <meta property="og:image" tag). Imgur.com does the same. You have to use direct link to JPEG file, not the link to the "image page". ‎- псы в рапиде