Six world premieres are on the docket for the 27th edition of the Boston Film Festival, unspooling at the Stuart Street Playhouse Sept. 16-22.Opening night will feature the world preem of “Certainty” with actors Giancarlo Esposito, Tom Lapinski and Bobby Moynihan expected to be joined by screenwriter Mike O’Malley, and of “After Fall, Winter” with writer-producer-director-star Eric Schaeffer and cast member Deborah Twiss in attendance. On Sept. 21, director Jim Hemphill and stars Lea Thompson and John Shea will appear with their feature film “The Trouble With the Truth.” In addition, filmmakers Jennifer Jessum and Simon Joseph will bow their documentary “Holy Man: The USA vs. Douglas White,” about an 88-year-old Lakota Sioux medicine man who spent 17 years in prison but was eventually cleared by evidence uncovered during the making of the film. Also making its debut is “How to Start a Revolution,” a look at Gene Sharp and his non-violent approach to overthrowing dictators. The locally produced doc “Give Me a Shot of Anything: House Calls to the Homeless” will also be screened. Unable to compete with bigger and more high-profile fests in Toronto and New York, Boston has tried to carve out a niche as a venue for indie films. In addition to the world premieres, a number of features and docus will have U.S. or regional premieres. There will be sneaks of “Serial Buddies,” with producer Maria Menounos and director Kevin Undergaro introing their film, and the HBO documentary “The Education of Dee Dee Ricks,” about women and breast cancer, with both Ricks and director Perri Peltz expected to attend. All told 17 features and docs have been scheduled, as well as two programs of shorts. The fest’s closing-night film or films have yet to be announced. For further information on the fest and the films go to http://www.bostonfilmfestival.org.