Petro Vlahos - Telegraph His original concepts and innovations have been enhanced and expanded over the years, making possible entirely seamless composites which preserve fine details such as hair, smoke, mist, motion blur and shadows while automatically suppressing "blue spill" (whereby light from the blue screen behind washes across the foreground subject). Refinements of Vlahos's pioneering technique were used to make many of the blockbuster films of the 1990s, notably Titanic (1997), in which scenes that had hitherto been too dangerous, expensive or difficult to film were finally possible. Special effects triumphs in contemporary films like Avatar (2009), in which blue-skinned Na'vi dwell among floating mountains, and Life of Pi (2012), in which the tiger, the ocean, and sometimes even the boy Pi himself are digital creations, also derive from Vlahos's work. Petro Vlahos was born on August 20 1916 at Raton, New Mexico. After graduating in Engineering from the University of California at Berkeley in 1941, he became a designer at Douglas Aircraft during the Second World War. After working as a radar engineer at Bell Laboratories, he joined the Motion Picture Research Council, spending six months devising a complex laboratory process that separated blues, greens and reds before recombining them. The result - his patented "colour-difference system travelling matte scheme" - created the breathtaking visual effects in Ben-Hur . Having minimised the unwanted "halo" side-effect that had dogged earlier attempts, he modified the technique to work on green screens as well as blue. On television, technology based on Vlahos's work was regularly seen in episodes of Doctor Who, and made it possible for weather presenters to point at sun and rain symbols that only their viewers can see. In all Vlahos held more than 35 patents for film-related gadgetry, and in 1978 received an Emmy for his work. Petro Vlahos is survived by his wife, Virginia, their son and daughter and two stepchildren. Petro Vlahos, born August 20 1916, died February 10 2013