by Benjamin Bergery
Photos courtesy of Universal Studios and Éclair Laboratories

Music is playing softly in a big, darkened room. Seated in the penumbra, three men watch a tiger roar silently on an 8-foot screen. Colorist Yvan Lucas clicks a computer mouse and the image freezes. “A little cold?” asks director of photography Jean-Marie Dreujou, AFC. “I’ll add a couple points of yellow,” Lucas answers. He clicks the keyboard twice and the image warms up. “Looks better,” comments colorist Bruno Patin, who is sitting nearby.

Inside a digital-intermediate (DI) suite at Éclair Laboratories outside Paris, Dreujou is timing the high-definition video/35mm hybrid Two Brothers (see AC July ’04) with Lucas, assisted by Patin. Lucas is using Discreet’s Lustre to grade the digital image and a Barco DLP 50 projector to display it large-scale. Later, the graded digital file will be transferred to an intermediate film stock using an Arrilaser film recorder.

Dreujou’s cinematography credits include Last Trading Post in India, The Children of the Marais, Little Chinese Seamstress and The Man on the Train. He has been nominated twice for France’s Cesar, for The Whims of a River in 1996 and Girl on a Bridge (which was graded by Lucas). Two Brothers was his first HD project; he has since photographed two more.

Lucas is a pioneering color timer with 40 features to his credit, including Delicatessen, City of Lost Children and Seven (all shot by Darius Khondji, ASC, AFC), as well as Amélie (shot by Bruno Delbonnel, AFC).

About 50 films made in France last year, roughly one quarter of the national output, made use of the DI process, and Éclair has established itself as a leader in the field. Two Brothers presented some unique challenges in that it was shot mostly in HD; 35mm was used for about 15 percent of the picture.

Philippe Soeiro, creative director at Éclair, explains that the postproduction workflow for Two Brothers was designed to treat the project “as if it were shot entirely on film.” First, all of the 35mm and HD footage was transferred to a Discreet Smoke workstation. The HDCam image was converted from its native YUV video format to RGB, the computer standard.

Digital-effects supervisor Frederic Moreau notes that Two Brothers has almost 550 visual-effects shots, many combining HD, 35mm and computer-generated (CG) elements. To create uniformity between HD and film, the 35mm images were scaled down to the HD size of 1920x1080 pixels and then transferred to the HD depth of 8 bits per color. In addition, grain was removed from some of the film footage. Moreau explains that the effects sequences were composited and “pre-graded” before they were transferred to the Lustre for final grading.

Before use in the Lustre, all of the HD images were transferred from linear to 10-bit log format. Soeiro notes that this colorspace conversion was “one of the delicate steps” in the post process, and that the conversion look-up table (LUT) was fine-tuned to allow for more detail in the dark areas. He explains that the log format enables the cinematographer and colorist to work using film-style “printer points” when grading on the Lustre, whereas the linear format does not. Dreujou cautions that perhaps because of the conversions, the raw Lustre HD footage needed work before it resembled the images he had seen on the hi-def monitor during production.

Both Dreujou and Lucas were delighted to work with the same yellow, cyan and magenta points that are used in photochemical color timing. “My origins are in photochemistry,” notes Lucas. “I came to digital because I wanted to follow the evolution of the technology, but my heart still beats for photochemical treatments. I hope one day to combine digital and photochemical techniques to create a new look.”

Two Brothers’ final graded image file was transferred from the Lustre to the Arrilaser, where it was recorded onto Eastman 2242 intermediate film. The Arrilaser output six 15- to 20-minute reels that served as a “negative” for a traditional photochemical process that involved contact printing to an interpositive (IP) and internegative (IN), all on 2242. The release prints were then made on Kodak Vision 2383.

Soeiro explains that Two Brothers was graded using Lustre “proxy” images that had lower resolution than but identical color values to the HD originals. These smaller proxy images were sized to match the 1280-pixel width of the “1K” Barco DLP 50 projector. The proxy images were manipulated in real time on the Lustre, while the original HD images were conformed offline by a “render farm.”

DIs would not be possible if the projected digital images did not accurately represent the final result on film. Soeiro credits the 3-D Display LUTs that Éclair developed in-house for enabling great precision in mimicking the way the image will look on positive film stock. Whereas a “normal” (2-D) LUT transforms individual red, green or blue values from one colorspace to the other, a 3-D LUT establishes correspondences between actual colors defined by triads of red, green and blue. Notes Soerio, “With this method, you can decide, for example, that the oranges in the digital color space should be displaced more toward the red of the film color space, without displacing the other colors nearby. This kind of thing is impossible in 2-D LUTs, where each red, green or blue component is treated separately. Only 3-D LUTs enable you to make two colorspaces coincide perceptually.”

“What’s pleasant about the digital projector,” observes Dreujou, “is that it’s on a big scale, so you can more accurately adjust the volumes in the image. What’s unpleasant is that the image quality is soft because it lacks definition.” Although the digital-proxy projection was remarkably close to 35mm, Dreujou noticed some subtle differences in contrast and saturation. “We found we had to augment the contrast and saturation slightly in the digital image in order to get the desired result in film,” says the cinematographer. “Also, we ended up with something slightly too blue in digital projection to get what we wanted in film projection.” He adds that the film projection also revealed more detail in the blacks than the digital one did.

The time it takes to get film out of an Arrilaser marks a key difference between digital and traditional grading. At 1.5 to 2.5 seconds per frame, it takes 12-15 hours to record a 20-minute reel of film with the Arrilaser, whereas a traditional film reprint is done in real time. Because many film projects are competing for valuable Arrilaser time, Éclair has instituted the practice of “digital dailies,” two- to three-minute rolls of selected excerpts. These serve as a regular check of the film output of the grading process and are short enough so that it is practical to produce them every couple of days.