Fix main.c:19:6: warning: no previous prototype for ‘hex_to_image’
Fix main.c:19:6: warning: no previous prototype for ‘hex_to_image’

OpenISS/OpenISS,OpenISS/OpenISS,OpenISS/OpenISS,OpenISS/OpenISS,OpenISS/OpenISS,OpenISS/OpenISS,OpenISS/OpenISS