The Silence of the Lambs star wore padding and facial prosthetics to transform into the portly, smartly-dressed director for Hitchcock after refusing to pile on weight for the role.
But he insisted on turning up to rehearsals alongside co-stars Dame Helen Mirren and Scarlett Johansson in formal clothes to perfect his portrayal of the cinema icon.
He tells Deadline.com, ""I spent about an hour and half in make-up each day. I also shaved my head, because I'm quite gray and Hitchcock used dye - that awful red dye. And then, once you get into the mask, I'm not Alfred Hitchcock; I'm Anthony Hopkins playing the guy.
""So I used what I could. I wouldn't go on the set till I was completely dressed. I wouldn't go on in jeans, even in rehearsal. If you're going to rehearse a scene, become the character. I wanted to feel the illusion of what I was trying to do, and that's what I did.""