London-born writer, producer, actor and director Ray Burdis insisted his biopic, The Wee Man, about the former hitman and drug dealer was not intended to be a documentary, adding: "It does glamorise violence but every film glamorises its subject matter."
The film, which has been critically panned, has drawn condemnation from senior police and MSPs for putting a "gloss" on Glasgow's brutal gang scene. But Burdis, who also produced thriller The Krays, claimed the same charge could be levied against Mafia-inspired movies.
He said: "When you watch The Godfather, these people are real, they are Mafia, it's real and they kill people and it's a very glamorous film and you enjoy watching it."
Victim support groups have refused to be drawn on his comments, saying they do not want to generate any more publicity for the movie.
But Scottish Labour justice spokesman Lewis Macdonald MSP said the film added "insult to injury" for Ferris's victims and called on him to donate proceeds to communities blighted by crime.
Ferris became involved with Glasgow underworld figure Arthur Thompson aged 19, when he began collecting debts on Thompson's behalf. Ferris was linked to stabbings, blindings and knee-cappings.
Most of the film, which stars Greenock-born actor Martin Compston, was shot in London and not Glasgow because of what the director described as a "lack of co-operation" from city authorities, a decision which Burdis said he understood.
Comments by Burdis saying the film glamorises violence are at odds with Ferris's view of the piece.
Ferris said: "When people are looking at actual events, at what happened, and putting that in front of a camera, does that glorify violence?
"There is a historical aspect to it. It's just a bit unfortunate that it's an 18 certificate. I would have liked a young audience to look at it and think, 'Do you want to end up with that kind of life? No.'"
In 1997 Ferris was sentenced to 10 years in jail for having illegal weapons. When he was released, he pledged to give up crime. He now works in the security business.
Film review, Page 55