Victim George Rutherford, 26, suffered severe head injuries and only emergency surgery saved his life. He was in hospital for two months.
Lord Bannatyne told attacker Alan Payne, 39: "I watched the video of what you did. You were the principal person involved in what, in my view, can properly be said to be a brutal, horrific, merciless and cowardly attack on another man." The video showed Mr Rutherford being punched and kicked as he lay, helpless, in a pedestrian precinct in Irvine, Ayrshire.