Following the recent leak of the Sony Xperia Z wallpaper, it looks like the rest of the wallpapers from the same set have leaked along with a bunch of images that will be used with the new lock screen. The images of the wallpaper are 1440 x 1280 pixels in size, suggesting it comes from a 2012 Xperia handset with 720p display (or perhaps even an unknown 2013 model) rather than the Xperia Z/ZL that has a 1080p display. Anyway, you can download the 15MB file here and try some of these yourself – the wallpapers work without any adjustment needed on a Xperia S or Xperia T.
Thanks Ambroos & Dacha!
