Color LUTs for the Film Aesthetic

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Newer cameras offer the ability to record in log gamma profiles. Those manufactured by Sony, ARRI and Canon have become popular, and with them, so have a new class of color correction filters used by editors. Color look-up tables, known as LUTs, have long been used to convert one color space to another, but now are increasingly used for creative purposes, including film stock emulation. A number of companies offer inexpensive plug-ins to import and apply common 3D color LUTs within most NLEs, grading software and compositors.

While many of these developers include their own film look LUTs, it is also easy to create your own LUTs that are compatible with these plug-ins. A commonly used LUT format is .cube, which can easily be generated by a knowledgable editor using DaVinci Resolve, AMIRA Color Tool or FilmConvert, to name a few.

Most LUTs are created with a particular color space in mind, which means you actually need two LUTs. The first, known as a camera profile patch, adjusts for a specific model of camera and that manufacturer’s log values. The second LUT provides the desired “look”. Depending on the company, you may have a single filter that combines the look with the camera patch or you may have to apply two separate filters. LUTs are a starting point, so you will still have to color correct (grade) the shots to get the right look. Often in a chain of filters, you will want the LUT as the last effect and do all of your grading ahead of that filter. This way you aren’t trying to recover highlights or shadow detail that might have been compressed by the LUT values.

Color Grading Central’s LUT Utility

df_lut_2a_smThe LUT Utility has become a “go to” tool for Final Cut Pro X editors who want to use LUTs. It installs with eleven basic LUTs, which include a number of camera log to Rec 709 patches, as well as several film looks for Fuji, Kodak, 2 Strip and 3 Strip emulation. LUT Utility installs as a Motion template and also appears as a System Preferences pane. You may use this pane to install additional LUTs, however, you can also install them by placing the LUT file into the correct Motion template folder. Since it uses LUTs in the .cube format, any application that generates a 3D LUT in that format can be used to create a new LUT that is compatible with LUT Utility. When you apply a LUT Utility filter to a clip or an adjustment layer inside FCP X, the inspector pane for the filter gives you access to all recognized LUTs through a pulldown menu. The only control is a slider to adjust the amount of the LUT that is applied.

Color Grading Central also has a partnership with visionColor to bundle the Osiris film emulation filters separately or together with LUT Utility. The Osiris set includes nine film emulations that cover a number of stocks and stylized looks. They are provided in the .cube format. Although both the Color Grading Central and Osiris filters are offered for FCP X, it’s worth noting that the LUTs themselves are compatible with Avid Media Composer, Adobe Creative Cloud, Autodesk Smoke and DaVinci Resolve. One thing to be careful of in FCP X, is that Apple also includes its own log processing for various cameras, such as the ARRI ALEXA, and often applies this automatically. When you apply a LUT to log footage in FCP X, make sure you are not double-processing the image. Either use a LUT designed for Rec 709 imagery, or set the FCP X log processing for the clip to “none”, when using a LUT designed for log color space.

In addition to Osiris, visionColor and Color Grading Central developed the ImpulZ LUT series. ImpulZ comes in a Basic, Pro and Ultimate set of LUTs, based on the camera profiles you typically need to work with. It covers a mixture of stock brands and types, including negative print and still film stocks. The Ultimate collection includes about 1950 different LUT files. In addition to camera profiles, these LUTs also cover four gamma profiles, including film contrast, film print, VisionSpace and Cineon Log (Ultimate only). The VisionSpace profile is their own flatter curve that is more conducive to further grading.

Koji Color

df_lut_2b_smAnother LUT package just released for Final Cut Pro X – but also compatible with other applications – is Koji Color. This is a partnership between noted color timer Dale Grahn (Predator, Saving Private Ryan, Dracula) and plug-in developer Crumplepop. This partnership previously resulted in the Dale Grahn Color iPad app. Unlike many other film emulation packages that attempt to apply a very stylized look, Koji Color, is design to provide an accurate emulation of a number of popular print stocks.

As implied by the name (Koji appears to be a mash-up of “Kodak” and “Fuji”), three key stocks from each brand are covered, including Kodak 2383, 2393, 2302 (B&W) and Fuji 3514, 3521, 3523. Each print stock has specific contrast and color characteristics, which these LUTs seek to duplicate. In FCP X, you select and apply the correct version of the filter based on camera type. Then from the inspector, select the film stock. There are extra skiers to tweak saturation and exposure (overall, hi, mid, shadow). This helps you dial in the look more precisely.

Koji Color comes in three product packages. The basic Koji DSLR is a set of filters that you would apply to standard HD cameras running in the video and not log mode. The output format is Rec 709 video. If you shoot with a lot of log profile cameras, then you’ll want Koji Log, which also includes Koji DSLR. This package includes the same LUTs, but with filters that have built-in camera patches for each of the various camera models that shoot log. Again, the output format is Rec 709.

The most expensive bundle is Koji Studio, which also includes the other two packages. The main difference is that Studio also supports output in the DCI-P3 color space. This is intended for digital intermediate color correction, which goes beyond the needs of most video editors.

SpeedLooks

df_lut_3_smLookLabs is the development side of Canadian post facility Jump Studios. As an outgrowth of their work for clients and shows, the team developed a set of film looks, which they branded under the name SpeedLooks. If you use Adobe Creative Cloud, then you know that SpeedLooks comes bundled for use in Adobe Premiere Pro CC and SpeedGrade CC. Like the other film emulation LUTs, SpeedLooks are based on certain film stocks, but LookLabs decided to make their offerings more stylized. There are specific bundles covering different approaches to color, including Clean, Blue, Gold and others.

SpeedLooks come in both .cube and Adobe’s .look formats, so you are not limited to only using these with Adobe products. LookLabs took a slightly different approach to cameras, by designing their looks based on the starting point of their own virtual log space. This way they can adjust for the differences in the log spaces of the various cameras. A camera patch converts the camera’s log or Rec 709 profile into LookLabs’ own log profile. When using SpeedLooks, you should first apply a camera profile patch as one filter and then the desired look filter as another.

If you use Premiere Pro CC, all you need to do is apply the Lumetri color correction effect. A standard OS dialogue opens to let you navigate to the right LUT file. Need to change LUTs? Simply click the set-up icon in the effect control window and select a different file. If you use SpeedGrade CC, then you apply the camera patch at the lowest level and the film look LUT at the highest level, with primary and secondary grading layers in between. LookLabs also offers a version of SpeedLooks for editors. This lower-cost package supplies the same film look LUTs, but intended for cameras that are already in the Rec 709 color space. All of these filters can be used in a number of applications, as well as in FCP X through Color Grading Central’s LUT Utility.

Like all of these companies, LookLabs has taken time to research how to design LUTs that match the response of film. One area that they take pride in is the faithful reproduction of skin tones. The point is to skew the color in wide ranges, without resulting in unnatural skin tones. Another area is in highlight and shadow detail. LUTs are created by applying curve values to the image that compress the highlight and shadow portion of the signal. By altering the RGB values of the curve points, you get color in addition to contrast changes. With SpeedLooks, as highlights are pushed to the top and shadows to the bottom, there is still a level of detail that’s retained. Images aren’t harshly clipped or crushed, which leaves you with a more filmic response that rolls off in either direction.

FilmConvert

df_lut_4_smFilmConvert (an arm of Rubber Monkey Software) is now in the 2.0 version of its popular film emulation application and plug-ins. You may purchase it as a standalone tool or as filters for popular NLEs. Unlike the others that use a common LUT format, like .cube, FilmConvert does all of its action internally. The plug-ins not only provide film emulation, but are also full-fledged, 3-way color correction filters. In fact, you could use a FilmConvert filter as the sole grading tool for all of your work. FilmConvert filters are available for Adobe, Avid, Final Cut and in the OFX format for Resolve, Vegas and Scratch. The Resolve version doesn’t include the 3-way color correction function.

You may keep your setting generic or select specific camera models. If you don’t have that camera profile installed, the filter will prompt you to download the appropriate camera file from their website. Once installed, you are good to go. FilmConvert offers a wide range of stock types for emulation. These include more brands, but also still photo stocks, such as Polaroid. The FilmConvert emulations are based on color negative film (or slide transparencies) and not release print stocks, like those of Koji Color.

In addition to grading and emulating certain stocks, FilmConvert lets you apply grain in a variety of sizes. From the control pane, dial in the amount of the film color, curve and grain, which is separate from the adjustments made with the 3-way color correction tool. New in this updated version is that you can generate a 3D LUT from your custom look. In doing so, you can create a .cube file ready for application elsewhere. This file will carry the color information, though not the grain. The standalone version is a more complete grading environment, complete with XML roundtrips and accelerated rendering.

Originally written for Digital Video magazine / CreativePlanetNetwork

©2014, 2015 Oliver Peters

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