What is a LUT? How LUTs work in video, and how to use them

What is a LUT in video?

A LUT is a table of answers: for each colour that goes in, the colour that comes out. Software reads every pixel, looks up its colour in the table and writes the answer, which is why a LUT is fast and gives the same result in every app that reads it.

There are two kinds:

• A 1D LUT holds one curve for each of red, green and blue. It can change brightness and contrast, and tint the picture, but it cannot mix the channels, so it cannot turn one hue into another.
• A 3D LUT is a cube of sample colours: a 33-point cube, a common size, holds 33 × 33 × 33, or 35,937, of them. Colours between the samples are blended from their neighbours. Because it works in all three channels at once, a 3D LUT can move skin towards orange and the sky towards teal in one step. It is what people mean when they say "a LUT" in video.

Either way, a LUT is a fixed, colour-for-colour change. The same input colour always gets the same output, wherever it sits in the frame. A LUT cannot tell a face from a wall of the same colour, cannot darken the corners, and does not know whether your shot was exposed well.

What is the difference between a camera LUT and a creative LUT?

A camera LUT corrects; a creative LUT styles. They do different jobs and expect different footage.

Log footage is why camera LUTs exist. A camera recording in log stores a wider range of brightness by squeezing it, so the picture comes out flat and grey, ready to be graded rather than watched. The camera LUT undoes the squeeze for that camera's sensor and profile. Apple's guide to Final Cut Pro keeps the two apart: a camera LUT is applied to the media before any effect, and a custom LUT is an effect you can place anywhere in a clip's effect order.

What is inside a .cube file?

Plain text. A .cube file names its size, such as LUT_3D_SIZE 33, then lists one row of three numbers for every sample, the red, green and blue that come out, each from 0 to 1. Sizes of 17, 33 and 65 points are common: bigger cubes are more precise and larger on disk. Because the format is so simple, nearly every editor, grading app and many cameras and monitors read it, which is why looks are bought, sold and shared as .cube files.

How do you use LUT color grading without spoiling the picture?

Most bad LUT grades come from the same few mistakes. Avoid them in this order:

1. Correct before a creative LUT. A look is built for a balanced picture. Feed it a dark, blue shot and it exaggerates both. Set exposure and white balance first.
2. Use the camera LUT that matches your profile. A table built for one log profile gives wrong colour on another, even from the same maker.
3. Expose log properly. A camera LUT expects the exposure the maker designed for. Underexposed log comes through it dark and noisy.
4. Convert once. If your editor already converts the log, adding the same LUT on top doubles the contrast and saturation.
5. Turn it down. Many creative LUTs are too strong at full. Lower the strength where your editor allows it, or reach the look with adjustable controls instead.
6. Check skin and highlights. A LUT can push skin orange or green and clip the brightest parts. Watch the vectorscope's skin line and the waveform's top edge.

How do you use a LUT in Sharpy?

Sharpy accepts the format looks are traded in: a camera maker's log-to-Rec.709 LUT, a colourist's pack or a client's brand grade.

1. Choose the table. File ▸ Grade Through a Lookup Table… and pick the .cube.
2. Hear what it does. Sharpy says in words where the LUT puts black, the shadows, the midtones and white, for example "lifts black to 0.045; brightens the midtones; tints the midtones", so you know before you look.
3. See it on your footage. The GRADE section of the Look tab names the file, with Change and Off. The viewer matches the export byte for byte.
4. Grade around it. The LUT goes on last, after every look, and stays on when you switch the looks off to compare.
5. Export. The edit records which LUT it used, so a later render keeps the grade. If the file has moved, Sharpy names it and refuses it rather than playing or exporting the edit ungraded.

Camera log is handled first. Each clip's log is detected or chosen and converted to Rec.709 with the right maths, and your creative look goes on top, so a LUT is never stacked on log by mistake. Your LUTs sit on a shelf beside the looks, previewed on your own frame, and camera makers' tables are fetched for you, among them DJI's D-Log M LUT. A table that is broken, with rows missing or a 1D table passed off as a cube, is refused by name rather than used.

One thing a LUT cannot do is spare a face: it changes skin along with the room. Sharpy's own looks can go around the person instead. On a test recording, its moods laid around the speaker moved their skin by less than 0.1 on the ΔE2000 scale, where about 1 is the smallest difference most people can see. Colour grading in Sharpy shows how, and colour matching your clips comes before any look.

Sources

Checked on 18 October 2026.

• Apple: Apply LUTs in Final Cut Pro for Mac
• DJI: LUT official download