Guide to LUTs: How to Color Grade Films With LUTs
Written by MasterClass
Last updated: Aug 19, 2021 • 3 min read
Color grading can be a time-consuming part of the post-production process, which is why many directors and colorists rely on a look-up table, or LUT, to save a particular color as a template for later use. Learn more about the role of LUTs when color grading a film.
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What Are LUTs?
LUT stands for “look-up table.” A LUT is a tool that lets filmmakers, editors, and colorists save particular color grades as a template. Think of a LUT as a color preset that a filmmaker can readily turn to when working on a project. For instance, the color editing process may require a team to convert a color space from a standard color space for televisions (such as Rec. 709) to a cinema standard color space (such as DCI-P3). If a colorist has one or more cinematic LUTs on file, they will find it easy to make this conversion.
Why Use LUTs?
Filmmakers, colorists, and editors use LUTs because they are convenient. Rather than create an entire color space from scratch every time you work on a video editing project, you can facilitate the color grading process by applying a LUT that comes with preset color profiles.
6 Types of LUTs for Basic Color Grading
Colorists use many types of LUTs for different purposes. Here are some of the most common:
- 1. Transformation LUT: This type of LUT transforms an image from one color space to another.
- 2. Viewing LUT: Camera crews use viewing LUTs on monitors during filming so that flat color spaces like S-Log or Log C (which capture low-contrast images with muted colors) can appear as something more usable (such as Rec. 709).
- 3. Calibration LUT: Colorists apply calibration LUTs to reference monitors or projectors to ensure uniform color characteristics (from skin tones to landscapes) in all stages of the editing and coloring process.
- 4. Log normalization LUT: This type of LUT tone-maps log footage into a standard color space like Rec. 709 or a cinematic color space like DCI-P3.
- 5. 1D LUT: A 1D LUT sets a display's white point, color balance, and overall contrast. The key is that a 1D LUT can only control one single value setting, which makes it less versatile than a 3D LUT. When searching for 1D LUTs online, look for files ending in a “.lut” extension.
- 6. 3D LUT: A 3D LUT captures a more complex color gradient than a 1D LUT can provide. As the name implies, 3D LUTs establish color and luma (the luminance of colors) in a three-dimensional color space by managing hue, saturation, and brightness. When searching for 3D LUTs online, look for files ending in a “.cube” extension.
How to Use LUTs When Color Grading a Film
The general rule of thumb when it comes to applying LUTs: First focus on creating usable footage, then get creative.
- 1. Start by normalizing your log footage. Camera log profiles provide a wide dynamic range, but once you've transferred your footage to a video editing workstation, you'll want to switch to a standard color space. From there, you can apply creative LUTs to achieve your own distinct cinematic look.
- 2. Proceed to color correction. Take note that color grading and color correction are not the same thing. While color grading is primarily creative, color correction is a technical necessity. If you're working off film footage where primary colors aren't even recognizable, you'll have no control over the color grading process. Make sure you do proper color correction before delving into the creative LUTs.
- 3. Experiment with different color combinations. Once your footage is properly set up in a standard color space, you can begin experimenting. Simply import LUT packs into your editing software, apply them to your footage, and watch your film project transform. There is no right or wrong way to apply a color grade to your film project, but keep the basics of color theory in mind.
- 4. Focus on the film color palette. Remember that color should serve your vision as a storyteller. You can make a cinematic world remarkably vivid with the right LUT, but you can also distract an audience if your color scheme feels random or chaotic. Serve your story and your world and reference the film’s color palette when choosing LUTs.
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