Main Production - Pre Production - Research into Costumes

Most film noir movies have a consistent theme and conventions about them. One of the conventions that they all have in common is the costumes that the characters wear. Usually the main male characters in film noir movies are detectives, or investigators. This shows that most people in a film noir will be wearing the same costumes, conventially this will be a detective long coat and a trilby hat, to back this up all you need to do is type in "film noir" onto google images and it comes up with the conventional costumes;