Where can I find hidden wallpapers on Nexus 7? I used to have this picture as Nexus 7's wallpaper, but the desktop restored to a blank wallpaper after I killed the UI process a few weeks ago. I tried to bring back this picture but it was no where in the wallpaper collection. Meanwhile, the gallery does not have this particular picture. 

As I searched for this picture on Google, I found there're other people who use it as their Android wallpaperhere. Therefore, I suspect that this picture should have come with Nexus 7's pre-built bundle. Moreover, I honestly didn't remember I deliberately downloaded it from somewhere else in the first place.

So, Nexus 7 or other android device owners, could you please check your wallpaper collection and let me know if you find it there? Also, if anyone knows where to obtain it, could you please let me know as well?

Many thanks. 

P.S. This is post is totally about my android device and what I'm trying to solve is an issue caused by Nexus 7. Android users are the mostly like group to help, so please don't downvote it for close.
I have Nexus 7 with stock Jelly Bean 4.2. Wallpapers are stored in /system/app/Launcher2.apk/res/drawable-sw600dp-nodpi as wallpaper_01.jpg to wallpaper_14.jpg but your picture is not here.

I checked wallpapers in version 4.1.1 online here:
https://bitbucket.org/neuralassembly/jcrom_packages_apps_launcher2/src/bd231599ae9f/res/drawable-sw600dp-nodpi

And your picture is not here too. What Android version do you have?