The MPAA has a rating system that allows parents to censor content for their children. MPAA ratings are shown before trailers for the movies, making it easy for parents to determine whether or not a movie will be appropriate, regardless of the content of the movie.
I propose a rating system for people with mental disabilities. As a person with PTSD, there are occasionally triggering scenes in movies that can be very upsetting. Rape victims are often surprised by graphic sex and rape scenes in movies that are advertised rather differently. Other people with mental illnesses such as depression can also be triggered by disturbing images or depressing themes.
I do not propose to censor directors, but to simply put in place a warning system for those who need it.