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September 2014
Issue: April 1, 2002

Color grading 1080i/24p

By: By Sam Dlugach
As the photochemical world converges with that of digital video, tools once available only to short-form clients are becoming part of the creative kit used by theatrical filmmakers. Movies of every scale and budget increasingly mix digital and optical effects, and in some cases, film- and video-originated imagery. Several such hybrid projects have passed through my da Vinci in the past few months.

Recently, I had the opportunity to provide color grading for a very special short film originating in both 1080/24p video and Super 16mm film, intended for theatrical exhibition. Different Places traces the impact of three different suicides on the survivors left behind. I knew writer/director James Edwin Barrett during college, and had even worked with him at a record store back in Memphis, but knew little then about his past. Jim's mother committed suicide when he was just 12 years old. Because of that life experience, Jim wanted to create a film that not only addressed serious issues about an often-taboo subject, but that was also entertaining for a general audience.

What a wonderful surprise, after many years, to be brought together with Jim again by B. Sean Fairburn, who served as DP on the project. Sean and I have been experimenting for months with the Sony HDW F-900 CineAlta camera and da Vinci 2K color corrector to optimize camera settings toward delivering maximum exposure latitude and maximum post-processing range. Sean is that rare combination of scientist and artist, and is a strong advocate of the 24p format for theatrical work.

Because of the film's daunting subject matter, Jim wanted to be able to roll camera on his actors long enough to capture subtle, genuine performances. Also, with his background as a video editor, he wanted to use layering and other video effects in his cut, and have them faithfully translate to the big screen. After seeing the quality of Fairburn's reel, Jim decided that 24p tape was the right shooting format to achieve a quality image and to allow virtually unlimited takes with his talent.

The project tells four stories in four different "places," each of which has its own distinct look. While tape-originated footage dealt with three "real" events from the recent past, Jim and Sean shot Super 16mm for parts of the story that occur in the "spirit" world. The Super 16mm aspect ratio of 1.78:1 fit nicely into the 16-by-9 HD frame, and working with film negative afforded us tremendous range in terms of achieving a unique look. With both media side-by-side, we could easily compare the relative qualities of each. It's an enlightening exercise that I highly recommend to all filmmakers.

Images from the Sony camera were easily manipulated within a given range provided that exposure to the CCD chip was safely within its linear range and the lighting ratios were relatively conservative. Since Sean has spent loads of time testing precisely these parameters, the images remained organic-looking from start to finish. We noted two constants: that underexposed reds become grossly noisy, and that over-exposure latitude is a mere 1/3 stop, after which you kiss highlight detail goodbye. With great success, we were able to manipulate saturation and contrast to achieve three unique looks from normal tape.

THE SPIRIT WORLD On the film side, things got much more experimental. Jim was looking for something bold to immediately cue viewers that we are in a spirit netherworld. The footage was marked with hard, high-contrast sunlight characteristic of the California desert location - the antithesis of the highly controlled lighting on the 24p tape material.

Whether information is stored as deposits of varying silver density or as bytes representing RGB color vectors, every image-recording medium operates on a transfer curve. The idea is: (data in) X (some transfer function) = data out. In a perfect world, this function would be completely linear with infinite resolution. If only! In truth, the desirable linear part of the transfer curve is painfully small. That's why film and (to greater extent) video have narrow ranges of exposure beyond which things begin to look less than wonderful. Much of the colorist's job is to squeeze the wide latitude of film stock into the compressed latitude of video so it is pleasing to the enormous latitude of the human eye. One of the most powerful tools in the da Vinci 2K color corrector is called custom curves. Using a graphical representation of the data in vs. data out function, a colorist can introduce non-linearity into the equation. Minor adjustments can fix a faded film stock problem; major manipulations can create effects as extreme as negation and solarization.

In the Different Places spirit world, Jim wanted a purple sky/yellow ground combo that left flesh tones normal. Custom Curves operate in four independent channels: red, green, blue and luminance. By lowering the exposure (data in) points at which red and blue reached maximum level (data out), and simultaneously raising the minimum levels to which red and green toe out (so that they never fall completely to zero), I forced unnatural colors into the highlights and shadows while leaving the midrange of the picture unaffected. It felt like I was working with a very unruly film element: slight exposure changes made huge differences on the screen, but we ended up with a striking image, surreal yet not psychedelic, and indeed altogether beautiful.

The result of this endeavor is a final HD tape that looks fantastic when projected. When the director eventually records this project out to film, he will have a print containing images that would be impossible to create photochemically, and performances that could not have been captured by shooting a limited amount of negative. Jim Barrett took on tough challenges thematically and artistically. By making wise use of available technologies, he achieved both goals admirably and created an emotional short film that could help many, many people.

Different Places made its debut at the Filmmakers Alliance in Park City, UT, in January 2002 during the Sundance Film Festival.