Split Screen: Dolby 24 allows side-by-side comparisons of film and digital


Few if any processing labs offer 35mm projection capabilities. For those still working with film, it's become more and more difficult to screen test footage and compare the quality of prints.

But in its Dolby 24 screening room in Manhattan, Dolby Laboratories can screen 35mm and 70mm footage through its Simplex projectors. "We have Simplex 35/70 projectors, probably the last 70mm Simplex made," says projection technician Robert Endres.

"These came in probably twenty years ago. They are the same models we had at Radio City. We have three-bladed shutters on them, and we can vary the speed. I've had them down to about 16 fps for a screening from the Museum of Modern Art."

The screening room is also equipped with a Christie CP4220 digital projector with 4K resolution and high-contrast lenses. The combination of film and digital equipment allows Dolby to offer side-by-side comparisons of the two formats. Filmmakers are starting to take advantage of the setup, to check both film timing and digital color grading.

Endres was for 25 years the head projectionist at Radio City Music Hall, where he worked with live stage shows as well as feature films. His predecessors built a collection of hand-machined split-aperture plates to solve an array of projection problems.

"You have two projectors, two prints, and you use split-aperture plates so you can get half an image from each print," Endres explains. "We used them for split-screen effects, or for the stage show. Now you can just make a matte, but in those days you couldn't do scenic backdrops digitally. You had to file a plate."

Endres describes one plate for title cards that would reveal "Merry Christmas" in various languages. Another was used during the stage show for an Israeli troupe with actors marching on treadmills before a CinemaScope backdrop.

The plates came in handy when Endres was asked to screen comparison prints of Gone With the Wind for its 50th anniversary. He used split-screen apertures to show a Los Angeles print simultaneously with one from the Museum of Modern Art.

During another quality check for the Judy Garland version of A Star Is Born, Endres came across a reel that had been wound incorrectly. When projected, it provided a flipped or reverse image. Endres was intrigued at the time, wondering if the process might be useful in comparing prints.

But it wasn't until a request from the colorist of the recent film The Promise that he thought about how to achieve the effect. "The Promise had a DCP release, all digital, but they were calling for one 35mm print for archival purposes," Endres recalls. "They wanted that print to look as much like the digital as possible, and the only way to do that was to screen them simultaneously."

Endres reverses the image in one format so the colorist can focus more easily on the range and contrast of imagery. At first he flipped the film image, but found that the soundtrack took up too much space. Now he reverses the digital image.

"You get a butterfly effect, more like a Rorschach test," he says. "The colorist sees exactly the same thing on both sides of the screen, hopefully at the same time."

Getting the two formats to run in synch proved more complicated than Endres expected. The screening room uses a Crestron touch-panel control to operate the Christie through Wi-Fi. That causes a lag time of about six seconds between starting the projector and seeing an image.

Dolby engineers designed a start switch for Endres to help align the two projectors. But he also had to account for how reels are formatted on DCPs. He can fast-forward to reel two, for example, then set the DCP back eight seconds to allow the film projector to get up to speed.

But that won't work for the first reel, which starts right at the first frame. Technicolor engineers saw the problem and suggested converting a 35mm leader to DCP to synch the two formats more closely.

Endres says that the process is still a "work in progress." But at this point the Dolby screening room may be the only place to compare digital and film effectively.

"The first test roll of The Promise, there was a difference between them, not in quality necessarily but in color and contrast," Endres remembers. "The colorist looked at it here, went back and made adjustments, brought it back after a second pass, and they were much closer. They were matching the film to the digital, but it could go the other way as well, obviously, matching digital to film."

The screening room runs quality checks for motion pictures shot on film. Endres handled all of the test screenings for The Beguiled, for example, for its 35mm showings at the Metrograph in New York and a theatre in Los Angeles.

"Sofia Coppola was here to check all the prints," he says. "She saw the whole thing once and she came back for a screening for the trailer. She came back to look at the L.A. print too. Then their postproduction supervisor came in and we went over every reel. We ran everything on one machine instead of two, which is better because you see it all with the same lamp."

Other filmmakers who have relied on Dolby 24 for quality checks include Baz Luhrmann for Moulin Rouge and Woody Allen for Manhattan. "Allen was here last May to screen test footage," he says. "He had a print both from the camera negative, a select release print, and a DCP. We ran the two prints side-by-side for him, and later the DCP. They flew the print in from the Academy out in Los Angeles. The woman who brought it was impressed by the digital quality, and I have to say the digital looked great because it was from the camera negative. Dolby Vision projectors will do even better because they have a much greater contrast range."

Endres points out that the filmmakers use the room for sound checks as well.

More recently, Endres ran test footage for Girls Trip in both digital and film, a four-minute roll of selected scenes. Filmmakers don't have many alternatives if they want a side-by-side comparison. Deluxe no longer offers 35mm projection, and Technicolor is considering discarding its projector.

Ironically, Endres points out that New York theatres like the Metrograph and the Quad are helping bring about a renaissance in film projection. And with Dunkirk screening in 70mm in 125 theatres, managers are scrambling to find enough qualified projectionists. At the same time, studios are making it more difficult to work in film.

But the projectionist is equally excited about the new Dolby Vision process. Dolby Vision projectors have been installed in the larger Dolby 88 screening room downstairs, and test screenings of Valerian: The City of a Thousand Planets and Baby Driver showed off the full potential of the process.

"We have a trailer to promote Dolby Vision 3D that's awesome, with colors you won't see anywhere else," Endres says. "The range is so wide, and the contrast is such that when the screen goes to black, it's real black."