Special effects pioneer Petro Vlahos, who advanced the blue-and green-screen technique used in the 1959 film Ben-Hur and 1964′s Mary Poppins, has died. His family tells the LA Times Vlahos died February 10 at the age of 96. Vlahos refined the composite-image process that allowed separately shot footage of actors and backgrounds to be combined into a single scene, a technique that became dominant in filmmaking and essential to movies like Avatar and the Star Wars saga. He vastly improved the so-called blue-screen effect for the chariot race in Ben Hur and a related technique for Mary Poppins that made Dick Van Dyke appear to dance among the penguins. Vlahos won a Best Visual Effects Oscar for the 1940 film The Thief Of Baghdad. He and his collaborators also won an Academy Award for their composite processes in 1965, and with his son, Paul, he shared another Oscar in 1995 for the blue-screen advances made by Ultimatte, the company he founded in 1976. “It’s hard to emphasize the import of his inventions,” Bill Taylor, a visual effects supervisor, said at the Scientific and Technical awards ceremony held by the Academy of Motion Picture Arts and Sciences the night before Vlahos died. “He created the whole of composite photography as we know it”. Vlahos also held more than 35 patents for movie-related gadgets, including low-cost screen-brightness meters, camera-crane motor controls and a method for detecting distortion in soundtracks.