What Are Luts and When You Should Use Them
Look-up tables, or LUTs, are all the hype right now. And I get why. You can achieve a bunch of looks and styles – cheap, easy, and fast. They are a favorite amongst analog lovers – allowing you to recreate classic film looks without spending all your money on film stocks.
For example, you can achieve the analog look cheap, easy, and fast. And if you’re just starting out, they’re a fantastic tool for the color correction and grading process. But what are LUTs? And when should you use them?
Damn good questions. Let’s find out.
Today we’ll get into the technical side. Trust me, once you get the gist of it, it will be easier to sort out how to make the best of them.
Now, I work in BlackMagic Design’s DaVinci Resolve – I find it the best color grading software out there. Plus, it’s free! But keep in mind that LUTs can be imported into any image editing software – like Adobe Premiere or Final Cut.
What Are LUTs?
A LUT, short for “look-up tables”, is basically an instruction file that takes the original image and transforms its pixel values (Hue, Saturation, and Luma) according to the instructions. It can shift parameters such as contrast, saturation, or hues.
On a less technical note, LUTs are just color presets for video footage, that can be used with all video editing software – be it DaVinci Resolve, Adobe Premiere Pro, Final Cut Pro X, or Avid. With a LUT, you can transform your boring footage and give it a unique look. With no hassle, and without being a color grading wizard.
While creative LUTs, which allow you to shift colors to emulate different film looks, are the most popular – a look up table has many use cases.
For example, you can use it to transform your Log Footage. Or to calibrate monitors on sets. Point is, LUTs are super versatile.
However, these are just a few examples of how they can be used. There are many other ways to use them.
What Are the Major Types of LUTs? Let’s Break Down the Confusion
The beauty of LUTs (but also the biggest weakness) lies in their versatility – you can use them in a more technical way or as a way of expressing your artistic vision.
It all comes down to which type of LUT you choose.
And these are the most common types of LUTs:
Log Normalization LUTs
1D and 3D LUTs
Calibration LUTs
Viewing LUTs
Creative LUTs
Technical LUTs
Technical LUTs are about converting and color correction. Generally, these take your image from one color space to another and are designed for specific camera brands.
1. Log Normalization LUTs
Log to Rec
If you worked with Log, you know it’s very flat, unsaturated, and might even have a strong green cast right out of the camera. After all, Log’s purpose is to get out the most of the dynamic range of the camera. And while it does that great, it lacks in colors. And usually, it comes with wider color spaces which offer more flexibility and better color in post production.
Well, using LUTs you can convert the Log footage into Rec. 709, a color gamut that is much smaller and more accurate to use since 99.9% of our monitors cannot reproduce a wider color space – leaving you with corrected colors, saturation, and contrast. Or you can convert the Log footage into DCI-P3 – if you’re creating motion picture movies.
You want to use LUTs in the camera while shooting. This way, you’ll get a good idea of the final look. It will show you if the footage is correctly exposed, or if you need to change things such as temperature or lighting techniques.
While creative LUTs are compatible with all video editing software – these normalization LUTs are meant for specific cameras and editing software. You could use a Canon normalization LUT on a Sony camera. But the results would be bad. Why? Because every camera brand has different specifications and handles color spaces differently.
2. 1D and 3D LUTs
These are the 2 formats a LUT can take.
1D LUTs transform and control one-dimensionally (usually the gamma, contrast, brightness, or white balance). The adjustment of a 1D LUT applies to everything – it doesn’t leave much room for flexibility.
The one instruction or parameter you set affects everything. 3X 1D LUTs can shift RGB values, but again, it does so for everything in the picture and it doesn’t allow colors to interact with each other. They work kinda like the curves tool in a video or photo editing software.
Source: Unsplash
3D LUTs, however, are way more flexible – these are the ones you use to create a cinematic LUT. But what is a 3D Lut? A 3D LUT map colors on a three-dimensional cube – hence the extension name (.cube). With these LUTs, colors can interact, they are corrected relative to each other. So, 3D LUTs are more flexible – you can also create changes in hue or saturation.
3. Calibration LUTs
The medium is the message. And when you color grade, you want the medium to be on par with the standards. That’s why some colorists like to use calibration LUTs. Your monitor is not to be trusted as it is – it can screw up colors and leave you with bad (or unintended) results.
Calibration LUTs will calibrate the display – so the end result is exactly what you intend it to be.
4. Creative LUTs
Creative LUTs are the fun ones out of the bunch. These allow you to emulate your favorite film stock, go from day to night, or add dramatic effects to your image.
To get the results that the LUT creator got, however, your input has to match their input. Otherwise, it’s like trying to paint with blue over yellow and expecting to get blue. Not feasible.
While these are quick and easy ways to add interesting looks to your footage – they are super limited. We’ll see why in a bit.
5. Viewing LUTs
Viewing LUTs are used by videomakers and filmmakers on set. When you’re on set, the video feed you see is in LOG or RAW – useful, but greyish, not contrasty, and overall just not how you envision your film to look.
If you don’t use these LUTs to convert from Log to another color space, it’s hard to know if your footage actually looks good.
With viewing LUTs, you get a more accurate result and that helps you choose which footage to use in post production process.
LUTs Limitations
Sure – LUTs are small files that make the job easier. But they are limited. These are the problems you’re facing when using them:
LUTs Can only hold so much information – hue, saturation, and luma values.
You are working against it – you can’t go inside the grade and adjust it to your own style, which can lead to colors breaking apart, time wasted, and frustrating experiences.
Your input doesn’t always match the input of the images on which the LUT was based. – most LUTs sold online aren’t tested on multiple cameras and picture profiles – so they might look good on some cameras and in some contexts.
You don’t get to put your own print on the footage – LUTs also take away the creative juices.
The biggest issues here are the overblown promises that some LUT creators make. Your video will not look like the creator’s footage unless you use the same camera, the same color space, a similar context, and the same LOG curve.
With that being said, sometimes they are useful. However, make sure to stress test them beforehand AND color correct the input image before applying any LUTs to it.
How to Install Luts to DaVinci Resolve
1. Open a project in DaVinci Resolve.
2. Go to Settings → Color Management → Lookup Tables.
3. Click on Open LUT Folder.
4. Copy the LUT folder with the LUT file into DaVinci Resolve’s LUT folder.
5. Close the folder and save.
How To Apply LUTs In DaVinci Resolve
1. Click on the ‘Color’ tab.
2. Right-click on a node – I usually choose the node at the end of the path. If I were to apply the LUT to a node in the middle or beginning, I would actually be making adjustments to the LUT, not so much on the footage itself.
3. 3D LUT → Choose a LUT and you’re done.
My point is not to say that LUTs are bad, but to recognize that they have limitations and they shouldn't be relied upon exclusively.
LUTs give you a good foundation for color grading and help save time, but many of them are created on different cameras and in different settings. If you're after a professional look for your film (or any other project), consider doing more than slapping a basic LUT onto it.
And you can create your own LUTs using Power Grades. Curious to see how? Check out my video on the topic!
I’m curious. What do you think about LUTs? Do you have any questions? Drop it on my forum or comment below 👇
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