Two men were assaulted outside McDonalds in Lancaster in the early hours of Saturday morning.
Police are appealing for witnesses following the attack in Cheapside on July 8.
Officers would like to speak to the man wearing the black T-shirt (pictured), following an unprovoked attack outside the fast food restaurant.
Anyone with information should contact Sergeant Dave Forshaw of Lancashire police on 101 quoting log reference LC-20170708-0252.
Lancashire Police said they apologise for the quality of the CCTV image.