A woman was punched in the face as she tried to defend her boyfriend during an unprovoked town centre attack.
A man, dressed in black, first hit the man knocking him to the ground outside Debenhams in Bournemouth Square.
As the woman attempted to defend him she was punched in the face and knocked to the ground.
Police have released a CCTV image of a man they want to speak to about the attack in the early hours of Sunday.
The victims, both in their 20s, needed hospital treatment for facial injuries.