Toward the beginning of The Wizard of Oz (1939), as she discovers that her house has landed on the Wicked Witch of the East, the heroine Dorothy (Judy Garland) dons a pair of ruby slippers. Sparkling and unforgettable in their redness, these shoes constitute the center of an important filmic moment: not only do they signal the beginning of the Technicolor era in perhaps the most popular film of all time, they also remain for viewers of all ages among the most memorable objects in twentieth-century screen history. Perhaps their centrality in pop iconography stems from the superior redness of Technicolor red—a red more elusive and more beckoning, more jewel-like and of a denser and greater purity than any other red we can see on the screen, and indeed more saturated and intense than reds we can see in everyday life.
To appreciate the long struggle to infuse color into moving images, one must first understand that in some respects the human eye is more sensitive to color than is film, and that in some respects film is more discerning than the human eye. The subtlest gradations of color and variations in saturation and hue that characterize objects are often beyond what film can record. But at the same time film does record, and intensively, the color temperature of illumination falling on those objects: the characteristic blue of daylight, for example, or the yellow of tungsten light, in either case something that we do not typically perceive with our eyes. Effecting color cinematography has therefore never been an easy task. Color in special effects cinematography is a persistent and vexing problem, especially in the combinations of positive and negative prints used in matte and rear-projection work. But the ability to infuse consistent color into the moving image has itself posed challenges throughout the history of the medium.