Audiences have been taking film color for granted since Dorothy left Kansas. And to many a casual moviegoer, gingham-clad Judy Garland peaking out of that sepia-toned house into a bright and verdant Oz might seem like the first—and last—big leap forward. But in reality, film color experts have been making strides toward bringing lifelike hues to the silver screen long before and after Dorothy started walking around in those ruby slippers.

Things started out simple: take some film, and paint in some color. But while the results of that turn-of-the-century practice were dreamy and gorgeous, it was more than a little time-consuming; filmmakers soon turned to Kinemacolor, a less labor-intensive fix that relied on eyeball hacking: By alternating between red- and green-tinted frames, you can create the illusion of a near-full range of color. Since your eyes can't keep up with the rapidly shifting pigments, your brain smushes them together. Still, no amount of flickering can bamboozle your eyes into seeing a color that isn't there, and Kinemacolor lacked blue. Eventually, Technicolor—the system that gave moviegoers their first glimpse of Oz—took its place. Rather than alternating frame colors, Technicolor captures red, green, and blue on separate film strips and then merges them into a single, full-color image.

In the early ’90s, like so many other things in the movie business, film coloration went digital. Films now tweak their coloring digitally, during post-production, which gives remarkable flexibility—as the dusty, desaturated look of the Coen Brothers' Oh Brother, Where Art Thou? can attest.

But capturing the vibe of the Deep South in the 1930s is a lot less complicated than, say, rendering the mystical, kaleidoscopic action sequences of Doctor Strange. Which is why Steve Scott, supervising finishing artist at Technicolor, prepared the film in HDR, or high dynamic range: the far boundary of modern image projection. The system allows filmmakers to work with a wider range of light, making their blacks blacker and whites whiter. That might not sound like much, but for visual effects geeks, it's cause for major hype: "It’s the biggest advancement I’ve seen since I’ve been in the this business," Scott says. And while it might take a while for HDR to come to a theater near you (the tech is new and expensive, and therefore relatively rare), even that won't be the final chromatic frontier. Somewhere, someone's dreaming up the perfect way to bring audiences the perfect view.