In WB on DVD, Fred Kaplan explains how Warner Brothers is “the new Criterion Collection”:
In the 1960s, long before film preservation became a popular cause, MGM was one of two Hollywood studios — the other was Disney — that decided to preserve all its films. They spent millions of dollars to repair, properly store, and in some cases meticulously restore original negatives, black-and-white nitrates, or duplicate copies. As for Warner Bros.’ own black-and-white classics, original nitrates were long ago donated to the Library of Congress or UCLA, which stored them in temperature-controlled rooms and left them, ever since, untouched. To the extent possible, Warner DVDs have been mastered from the original negatives, preventing degradation in detail, sharpness, color, and contrast.Then there’s Warner’s work with Technicolor. Even with careful preservation, color negatives fade over time. But Technicolor negatives can look as good as new after decades. This is because Technicolor films consisted of three black-and-white negatives, which ran simultaneously through a special camera. Light hit each film strip through a prism filter. Afterward, each film strip was coated with a dye, and the three strips were then aligned, on top of one another, to form a coherent color image. It was a complex, costly process, which lasted only from 1935-54. The point is that black-and-white negatives don’t fade. If the Technicolor black-and-white negatives have been stored well, and if some lab can replicate the Technicolor dye-processing, it should be possible to create a fresh print with perfect color.
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Many DVD studios now scan films at “high-definition” — or 1,080 lines. Warners is one of just a few that scan at 2,000 lines (or, in the parlance, “2K scanning”). Soon, beginning with a Wizard of Oz reissue later this year, it will start releasing Technicolor DVDs scanned at 4,000 lines (“4K scanning”). This is a significant number. Engineers estimate that if you digitally reproduced all the information on a frame of 35mm film, you’d need about 4,000 lines of data. In other words, at least theoretically, 4K scanning captures everything that’s on a film.