Natalie Kalmus Made This Whole "Color Film" Idea Catch On
Back when the crazy notion that movies could be seen in color was first floated around Hollywood, the studios actually fought against it. It was just too much trouble. Color film was already a thing (as was color in general), but there had yet to be a film that proved its marketability the way Avatar made you say, "Ugh, fine, yes, I guess I'll pay for 3D." Luckily, MGM was cooking up an adaptation of a book of clown nightmares called The Wonderful Wizard Of Oz and brought in Natalie Kalmus, wife of Technicolor's founder, as the film's color consultant. It was her idea to make everything as cartoonishly bright and vibrant as possible -- like Dorothy's iconic shoes, which were silver in the book.
Thematically, red makes more sense, since she's a murderer and all.
After the film's success, Hollywood saw a boom in Technicolor-made films, all of which were crafted and lorded over by one lady no one has heard of who ended up with 366 film credits to her name. See, at the time no one knew how to actually shoot in color, which meant that someone would have to create rules for what does and doesn't look good on camera. And so, Natalie took point -- going over each individual film that partnered with Technicolor to create a specific palette she deemed appealing, then passing it on to the set design and wardrobe department and sometimes even sitting in as the goddamn cinematographer. That means everything from the muted beauty of Rope to the vibrancy of The Ten Commandments was exclusively created by Natalie Kalmus, or as the Rope's screenwriter bitterly called her, the "High Priestess of Technicolor."
Paramount Pictures/Warner Bros.
To reiterate: SHE TOLD HITCHCOCK WHAT TO DO.