I had an image from a website which I set as my wallpaper inside the browser. I am wondering now where I can find the image in the file system, because I can't find it online anymore. I am rooted.
I'm not sure if it's the same on older systems, but on ICS it appears to save directly to
/data/data/com.android.settings/files/wallpaper. I set mine from the browser, pulled that file, then changed it to a .png extension and voilà - it was the image I had set.
It also appears that this file simply gets overwritten when you change your wallpaper, so I don't see a way to recover one once it's changed unless you have a copy of the image somewhere else.
This also appears to be where it's saved on CyanogenMod 7, so it's possible that this is the "standard" location (certainly a good place to check, at least).
I was annoyed by the exact same problem, so I have programmed an app that automatically saves your wallpapers and your live wallpapers too. It makes it easy to revert to a previous wallpaper. It is called Wallpaper Saver, by Appdictive, and it's free in the Play Store. (It does not require root access.)
This is a slight twist on the original question's context but may be useful to some who land here...
The location of the stock wallpapers is in an apk file that you should find on your device at
/system/framework/framework-res.apk. Pull that file to your computer and then browse its internals. A search for a file with
wallpaper in its name should prove fruitful.
The apk also contains other goodies such as stock icons.
You can use Root Browser, ES File Explorer, or other root folder browsers for this. Go to the root path using Root Browser (or ES File Explorer), and then:
When you try to open it, it won't open. To open it:
Copy the images with high size (maybe more than 80 KB since they got a quality) and paste them into a folder that is not in a root directory. (Just copy it to your "Downloads" folder or to your SD card)
Rename it. But when you do this, don't forget the ".jpg" at the end of the name you type. E.g. If I rename it to, "Sukkoth.jpg"
Open it using Gallery or any image viewer app.
In Android 7.1.2, I found them here, but they do not have an extension:
and here too as suggested on SiriusXM's answer:
Image extension can simply be added to those files.