I have a Samsung Galaxy S2 from Sprint. The phone is rooted but still running the stock OS.
My wife took a really good photo of our son and made it the lockscreen image. It no longer appears in the Gallery or anywhere else I can find on the phone.

I know the stock lockscreen images are stored in /system/app/TwWallpaperChooser.apk, but the current image is not there.

This old thread said would be in the device cache, but I have no idea where or what it would be named.

Any idea where I might find it?