A film adaptation is the transfer of a work or story, in whole or in part, to a feature film. Although often considered a type of derivative work, film adaptation has been conceptualized recently by academic scholars such as Robert Stam as a dialogic process. While the most common form of film adaptation is the use of a novel as the basis, other works adapted into films include non-fiction (including journalism), autobiographical works, comic books, scriptures, plays, historical sources and even other films. Adaptation from such diverse resources has been a ubiquitous practice of filmmaking since the earliest days of cinema in nineteenth-century Europe. In contrast to when making a remake, movie directors usually take more creative liberties when creating a film adaptation. Elision and interpolation In 1924, Erich von Stroheim attempted a literal adaptation of Frank Norris's novel McTeague with his film Greed. The resulting film was 9½ hours long, and was cut to four hours at studio insistence. It was then cut again (without Stroheim's input) to around two hours. The result was a film that was largely incoherent. Since that time, few directors have attempted to put everything in a novel into a film. Therefore, elision is all but essential. In some cases, film adaptations also interpolate scenes or invent characters. This is especially true when a novel is part of a literary saga. Incidents or quotations from later or earlier novels will be inserted into a single film. Additionally and far more controversially, filmmakers will invent new characters or create stories that were not present in the source material at all. Given the anticipated audience for a film, the screenwriter, director or movie studio may wish to increase character time or to invent new characters. For example, William J. Kennedy's Pulitzer Prize-winning novel Ironweed included a short appearance by a prostitute named Helen. Because the film studio anticipated a female audience for the film and had Meryl Streep for the role, Helen became a significant part of the film. However, characters are also sometimes invented to provide the narrative voice. Interpretation as adaptation There have been several notable cases of massive inventive adaptation, including the Roland Joffe adaptation of The Scarlet Letter with explicit sex between Hester Prynn and the minister and Native American obscene puns into a major character and the film's villain. The Charlie Kaufman and "Donald Kaufman" penned Adaptation, credited as an adaptation