Using a LUT for video editing

Sunday 8 October 2023, 13:31 by Nando Harmsen | 4,915 views | 4 comments

This article was translated from Dutch with the help of AI. Read the original.

When you record video, you will eventually come across the term LUT. LUT stands for Look-Up Table, but that does not tell you much about what it is. In this article, I explain it in simple terms.

A Look-Up Table, abbreviated to LUT, is a way of correcting the colour and contrast of your video footage. These are a kind of preset, but they are actually a little more advanced than that. There are LUTs for colour and contrast correction, and there are LUTs for colour grading.

The video settings of the Sony A6700 offer the option of special S-Gamut3.Cine/S-log3 and S-Gamut3/S-log3 settings. This footage looks flat, so it needs to be edited with a LUT.

LUT for colour and contrast correction

By default, video footage is recorded with normal colours and contrast. You can compare this to a JPEG photo from the camera. You can also record video footage in Raw, but not every camera gives you that option. A middle ground is recording in LOG, which captures a greater dynamic range without having to work with Raw video footage.

Video recorded in LOG often looks flat and colourless. It has virtually no contrast. This video footage still needs to be edited. You use a LUT, a Look-Up Table, for this.

These LUTs are specific to the camera brand. A LUT for an S-LOG file from Sony, for example, cannot be used for C-LOG3 from Canon. And vice versa. LUTs are also specific to the recorded format, such as Rec.709, Rec.2020, LOG, S-Cine, and all the other types.

Applying a LUT in Premiere Pro in the Lumetri Color panel. This changes the flat image into footage with optimised contrast and colours.
There are even 1D LUTs and 3D LUTs, each of which also has its own specific purpose. A 1D LUT uses a single correction for colour, contrast and saturation. You can usually recognise this by the file type, which has .lut as its file extension.

A 3D LUT has a separate correction for colour, brightness, contrast, gamma and saturation. The result is often better than with a 1D LUT. Applying a 3D LUT does require much more processing power. A 3D LUT is usually in .cube file format.

The difference between untreated video footage from the camera (right) and after applying the appropriate LUT (left)
After applying a LUT, you can further edit the video footage if necessary. You can brighten dark areas, darken light areas, or adjust the colour and contrast as you like.

A LUT for colour grading

Have you edited the video footage as you want it? Then you can apply colour grading. This gives your video a unique atmosphere, just as you see in films. It is often said for good reason that your video gets a cinematic look.

If you want, you can give your video footage a special look. This is also a LUT, but one aimed at adding a unique atmosphere.
A LUT for colour grading is therefore a real preset that gives your video a certain atmosphere. This can range from a colour overlay to complex edits. The possibilities are endless, which many LUT providers make grateful use of. You can download or buy entire packs of LUTs.

The three steps from an unedited image (left), via an edited image (middle), to a final result with a special look (left).
It is also possible to create your own LUT when you have made a good colour correction. You then save this setting as a .cube file. How to do this depends on your video editing software.

LUTs as part of the workflow

Do you ever record video, or are you planning to? If so, it is best to record in LOG so that you can edit the footage as well as possible when editing. Use a LUT to convert your Rec.709, Rec.2020, S-Cine or LOG file format to an optimised contrast and colour display, preferably with a 3D LUT.

Some cameras have built-in LUTs, specifically for reviewing your video recordings. This makes footage recorded in LOG look presentable. Without a LUT, it would look flat and unattractive. This is the setting on the Panasonic Lumix S5.
After that, you can give the video a unique style with a second LUT. This colour grading often produces a professional result. Especially when you have used different clips in your video, colour grading creates consistency.

In the video about the Canon EOS R7, I applied the LUTs mentioned in this article step by step.

It is important to first edit your LOG video format to the best possible result. Only then can you successfully apply colour grading. A different order, or skipping steps, will almost always lead to an unpredictable look for the video.

Would you rather not do any video editing? Then it is advisable not to record in LOG format.

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