The Wild West of LUTs

As the digital intermediate has quickly ushered in new, more efficient and flexible workflows, processes still vary widely from studio to studio, each using a different mixture of tools. While this allows each company to develop its own creative special sauce for digital intermediates, it also creates a host of problems when moving projects between facilities as standards and protocols tend to vary widely.

At the heart of the digital intermediate is the 3D Look-Up Table (LUT), enabling the output of the digitally created images to appear the same no matter what the output format or differing film stocks, all which handle color differently.

“On the same project, there will be one LUT used went outputting to film, based on the calibration information you get from the lab, another if you are going to project it digitally and a third LUT for outputting to an HD master,” explains Loren Nielsen (pictured above), principal/co-founder of Entertainment Technology Consultants (ETC), a technology consulting company helping manufacturers develop products for the entertainment industry. Specifically, ETC has worked closely with manufacturers of digital display technologies. Nielsen was recently appointed to board of directors at RKO Pictures. “The key is in designing the actual curves and numbers that go into your LUTs and combining that with process-control with your lab and your existing equipment.”

Sounds easy, efficient and flexible, right? Well, yes and no.

“If I took those same LUTs to a different facility the output would look completely different because it uses different equipment, processes and labs. All the LUTs are created internally at Technicolor to eFilm, Modern or Ascent, or any of those types of facilities,” says Nielsen. “So, one of the problems is this Wild West world that has been created with LUTs. If you’re making an effect at one facility and use one kind of LUT there and then send that effect down to a post facility for it to be incorporated into the DI, well they have a different LUT. That can cause problems. There isn’t any semblance of standardization yet. Basically what happens now is there has to be a lot of communication every time you move back and forth.”

While some of the color correction manufacturers are trying to develop LUTs that would be more portable, Nielsen doubts such rigid conformity would be possible. Even if a tool were to be created that could adjust to all the thousands of different combinations of monitors, film recorders, film stocks, color correction tools and output formats, post houses will likely resist any such standard tool.

“Right now, facilities look at their LUTs as providing them with a competitive advantage as they can say to their clients, ‘We can make your pictures look better than anyone else,'” says Nielsen.

So what can be down to put some order in this Wild West of LUTs?
Not so long ago, the realm of print graphics faced similar challenges and, through the International Color Consortium, a color management system was instituted that added standardization and encryption of metadata to make transferring data a simple process.

With industry-wide acceptance of the ICC spec in graphics, “Device profiles provide color management systems with the information necessary to convert color data between native device color spaces and device independent color spaces. The specification divides color devices into three broad classifications: input devices, display devices and output devices. For each device class, a series of base algorithmic models are described which perform the transformation between color spaces,” reads the ICC Web site (www.color.org).

Now, the ICC has formed a Digital Motion Picture Group to investigate how to institute an open, vendor-neutral, cross-platform, color management system architecture for the motion picture industry. Members include representatives from Adobe, Apple, Color Savvy Systems, Eastman Kodak, Electronics & Telecom Research Institute, Fuji Film Electronic Imaging, Hewlett Packard and Thomson, among others.

“Right now, there’s no automatic understanding of what has been done at another facility, notes Nielsen. “There’s a great need, and the film studios are very interested in this, for creating standards that can deliver information about the metadata along with the data itself. That’s what ICC did in the print world and it would seem wise to apply those techniques to the motion picture industry.”