The victim of a slashing during the earlier hours has released images of his injuries showing the physical cost of violence.
The assault happened at around 1.10am on Saturday outside of The Association bar in Nottingham Road, Ripley.
Detectives are now appealing for witnesses and CCTV footage.
A spokesman for Derbyshire Constabulary said: "Officers received a call from East Midlands Ambulance Service (EMAS) at 1.15am this morning to report the incident, in which a 22-year-old man was assaulted.
"The attacker is described as a man in his twenties, of slim build and with a shaved head. He was wearing blue jeans and a red t-shirt.
"The 22-year-old victim sustained minor injuries and was taken to hospital for treatment.
"Detectives are still working to establish what caused the victim's injuries, which are slash type wounds to his back.
"Anyone who witnessed the incident, or anyone who has CCTV that covers the area, is asked to get in contact.
"Please quote reference number 19*147334 in any correspondence and the names of the officers in the case Detective Sergeant Simon Cartwright and Detective Sergeant Sean Grainger."
Derbyshire Constabulary clarified that the injuries are described as minor, simply because they are not life-threatening and the victim was discharged from hospital a number of hours after being admitted.
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