Sometimes you just need to know where that image shown on your desktop is stored!
For this, there is a simple but effective line of text you can pop into your terminal.
defaults write com.apple.dock desktop-picture-show-debug-text -bool TRUE;killall Dock
This will render the image’s location pathname and image name over the desktop background image.
When you’re complete and you want to disable that over render of the image name, then simply type:
defaults write com.apple.dock desktop-picture-show-debug-text -bool FALSE;killall Dock
(Swapping the TRUE from before with a FALSE this time around)