Quote Originally Posted by psychoticmeow View Post
It even works for normal screens, because instead of displaying the image at 100% of its width you display it at 50% and let the browser scale it. The end result is pretty much the same, instead of serving a 100KB JPEG you're now serving a 60KB WebP.
I see that Google logo works that way, it's a 538x190 png that is displayed at 50% (269x95) on their front page.

So I tried to experiment a little with it.

14022 bytes: original logo11w.png
12644 bytes: lossless webp (cwebp -lossless -m 6)
12558 bytes: zopfli optimized png (100 iterations)

It looks like 10% improvement either way.