Marvel has released a behind-the-scenes featurettes for Avengers: Age of Ultron where the cast and crew explain the transformation process of the synthetic humanoid known as Vision.
See Paul Bettany transcend from the voice of J.A.R.V.I.S. into the Vision in Marvel’s “Avengers: Age of Ultron”! With ‘Avengers: Age of Ultron,’ writer/director Joss Whedon knew which characters he wanted to introduce, including the mysterious artificial being known as “Vision.” Whedon also knew that Paul Bettany, known for voicing the J.A.R.V.I.S. computer program in previous Marvel Studios films, would make for the perfect Vision!