Where is the lock-screen image stored?

I restored my phone and lost all my apps and save in the phone (Samsung S5). Once completed the restoring, I had back my lock screen image, and since it's important to me,I'd like to save it on my Pc, but I didn't find it anywhere ! Neither in Google's Photo, Dropbox and OneDrive Where can I look for it directly connecting my device to my laptop (if possible) ? Thanks a lot !