open image full screen with "open -a Preview"
Preview.app doesn't have command line options, but you could use AppleScript in Terminal:
open -a Preview somefile.png ; /usr/bin/osascript -e 'tell application "Preview"' -e "activate" -e 'tell application "System Events"' -e 'keystroke "f" using {control down, command down}' -e "end tell" -e "end tell"
Just replace somefile.png with the path/image you want; AppleScript invokes fullscreen.