Calibrating Color and Locking in a Look from Production Through Post
“In film days, we had a well-structured process where the DP was in charge of negative processing and everything was under the control of the DP and the colorist in the film lab,” said Gamma & Density CEO/founding partner Yuri Neyman. “The results were predictable. The moment when it switched to digital dailies, a digital camera workflow, and DI, we lost control.”
Panavision VP of Technical Marketing Al Mayer, Jr., Modern VideoFilm President of Studio Services Mark Smirnoff, da Vinci Systems Regional Vice President, Western United States Neil Kempt, Gamma & Density’s CTO/partner Bob Currier and project manager Alex Chernoff described how the CDL was employed on State of Play and demonstrated its use by shooting and coloring a small amount of footage.
All of the participants agreed that the core of the problem is communication between the cinematographer and colorist. How does the DP make sure that the image of the scene he/she photographed stays the same throughout production and post production, especially when it is being touched and manipulated by so many people?
The CDL is intended to take the guesswork out of the new digital pipeline. Its ten parameters include three each for gamma, gain and lift, with the tenth being saturation. “This is not a new color space or color correction system but rather a ‘translator’ between one color correction system to another system,” said Neyman. “In this case, Panavision’s Genesis can talk to Gamma & Density’s 3cP, which can talk to da Vinci’s color correction system, using 10 parameters that we all agreed upon that describe all varieties of color correction.”
At this stage, da Vinci is the only manufacturer of color correction systems that offers the ability to interface with the CDL; the plan is to have every color correction system to be “CDL-compliant.” [Other companies are in various stages of reaching CDL-compliance.]
Prieto is no stranger to Gamma & Density’s 3cP, having used it on Babel in 2006. State of Play was shot with a mix of 35mm and digital cameras (the Washington D.C. sections are digital).
The digital sequences were shot with the Panavision Genesis. Mayer, Jr. reported that the camera has been used to shoot 70 features to date; cinematographer Dean Semler has used it on five features. “It’s basically a film camera that happens to record with a digital medium,” he said. “We try to keep the interface simple so that if we spend 20 minutes taking you through it, you’ll get it all.” He pointed out that the camera’s digital recording medium is placed on the top or rear of the camera, exactly like a film magazine. “If you walk on the set, you’re not intimidating people by something they’re not familiar with,” he said. The Genesis can also be used with a solid-state recording system. “Wide color gamut allows you to intercut easily between Genesis material and film,” Mayer said.
Once the footage is acquired, it moves to Gamma & Density’s 3cP, which relies on a system of patented color charts and proprietary software, along with calibrated monitors, to ensure consistency of the look through the digital dailies and DI process. Gamma & Density project manager Alex Chernoff said he was involved with State of Play from the very beginning, helping to set up the Genesis camera. “We allow cinematographers to create pre-defined looks, something you often need to do in pre-production, along with choosing stocks and lenses,” he said. “We do physical tests with the film printed out and create a digital file that modifies all input from the Genesis or still camera and makes them look the way Rodrigo wants them to look.”
State of Play was shot with two Genesis cameras, and Chernoff emphasized that both cameras were “profiled” to be identical using the G&D chart.
Once the footage is in the 3cP system, said Chernoff, the cinematographer spends 10 to 20 minutes creating the desired look using a very simple interface. “No one who knows Photoshop would have any problem with it,” he said. “A before-and-after image, with monitors and scopes, allow you to monitor any changes that you do. You have all the tools you can get in color-correction. For example, RGB curves are popular.”
G&D’s 3cP software also allows the cinematographer to use masks and layers to apply isolated corrections to specific areas. “The best way to use 3cP is to capture a bit of video, select the most representative frame, color it, and save it as a CDL,” he said. “Rodrigo did this during the production day. Some people do it during lunch, other people do it at the end of the day. It’s simple: Select-Correct-Send.” The frames can be output as JPEGs, DPX files or any other popular file format.
After creating the desired look or looks, 3cP generates an electronic file that consists of the CDL, a file with before and after images, and all the scopes that were changed. “It goes to the post house – the attached CDL, 3D LUTs and metadata,” said Chernoff. “There, the colorist can, with the click of a button, get the identical look by applying these changes to the raw footage.” [On a film shoot, the cinematographer uses a calibrated digital camera to input into the system.]
Kempt described da Vinci’s current offerings in color-correction systems, including the 2K Plus system and the higher-end 4K/data Resolve.
“We receive the ASC CDL on a memory stick or some other storage device and put it into the list of the da Vinci color corrector as a separate item-no pictures, just values,” said Kempt. “The picture, whether it’s originated as film, tape or some other kind of acquisition, also ends up in the color-corrector. They are then matched up to the frames they apply to and you get the result. The result is viewed on the colorist’s monitor.”
Modern VideoFilm in Burbank handled digital dailies and Smirnoff, with chief systems engineer Siegfried Heep, was on hand to describe the experience of using the CDL in post. “We’re long-time customers of da Vinci and have been on the bleeding edge of science with them over the years,” said Smirnoff. “Our business is constantly looking ahead to the next invention, the next process.”
In creating dailies, said Smirnoff, “there is nothing to interpret on our side’we have to recreate what they did.” The “negative” was Sony SRW 4:4:4 elements, which came to the facility on a daily basis along with the ASC CDL list and reports from 3cP. “We would feed the ‘negative’ into the da Vinci and load the CDL, which is like an EDL for color,” said Smirnoff. “You’re not building the film but putting in different values for color. That’s what the CDL brings to us.”
“Now we have the base grade, the reference that the DP has on set,” he continues. “As a double-check, we have the images taken from the 3cP report, so we cross-reference to make sure it’s there. We use whatever we can get to create a circle back to production.”
Constant calibration is crucial, said Smirnoff. “It’s key to closing the loop and making sure everyone is looking at the same thing,” he said. “It also helps in speed and economics. My customers are the talent-DPs and directors-but also the studio heads and executives with an eye on the clock and their wallet. The CDL also helps to get through the dailies process a little quicker, by one-third to one-half.”
On State of Play, said Smirnoff, the dailies process was half as long as the film dailies process. “It was very successful,” he said. “We were on the bleeding edge of the CDL, but State of Play went very smoothly, quickly and efficiently based on the CDL process. Our system is now very streamlined and very solid.”
The CDL will also help at the end of the movie-making process, adds Smirnoff. “We save these lists in the da Vinci and apply them throughout the process. The CDL can give us a reference going into previews or the DI process.”
State of Play is currently being edited in the U.K., with an expected finish date by October. Smirnoff said Modern VideoFilm is in negotiation to do the DI, and stated his belief that the filmmakers intend to use the CDL in the DI process.
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