In the old days, when a new movie arrived at the theater, it was a collection of heavy, cumbersome cans containing the reels of 35-millimeter film. That physicality has nearly vanished. Today, a movie consists of a so-called Digital Cinema Package and looks like a plump DVD. It’s inserted into a player at the theater, and the distribution company transmits an electronic key that frees the film for screening.

On a film set, of course, the director of photography still frames an image and adjusts exposure and focus. But there are no silver salts on celluloid, waiting to be…