How to Build a Colour Grading LUT

You grade one clip until it looks right, and then you have eleven more from the same shoot. A LUT is how that grade becomes reusable — a fixed mapping from input colour to output colour that any editor can apply.

It’s also the thing people apply in the wrong place and then conclude their footage is broken.

What a LUT actually is

A colour lookup table stores output colours for a grid of input colours, and interpolates between the stored points for everything else.

A 33×33×33 LUT holds 35,937 samples across the RGB cube. That’s a lot of points, but it’s still a sample — the transformation between them is interpolated, which is why grid size matters when a grade has steep transitions.

A 17³ LUT is fine for a gentle grade. Push a strong S-curve or a sharp hue shift through a coarse grid and interpolation between widely spaced samples produces visible banding. That’s the argument for 33³ as a default and 65³ for aggressive work.

Lift, gamma, gain

Three controls that divide the tonal range:

Lift moves the shadows. Raising it lifts the black point, which is what produces the faded, film-like look.

Gamma moves the midtones, where most of the image lives. It’s the control with the largest perceptual effect.

Gain moves the highlights, scaling the top of the range.

They overlap rather than partitioning cleanly, which is why grading is iterative — adjusting gamma changes how lift reads, and you go back and forth.

Where the LUT goes in the pipeline

This is the part that goes wrong.

Log footage is recorded with a flat gamma curve to preserve dynamic range. It looks washed out because it’s meant to — the contrast is applied later.

A display LUT or creative LUT expects footage already converted to a standard working space. Apply one directly to log footage without converting first and you get the classic result: crushed shadows, blown highlights, and a conclusion that the LUT is bad.

The order is: log footage → conversion to working space → creative grade or LUT → output transform. Get that sequence right and the same LUT that looked terrible works properly.

Common mistakes to avoid

• Applying a creative LUT to unconverted log footage and blaming the LUT.
• Using a LUT as the whole grade rather than after basic exposure and white balance correction — a LUT is a fixed mapping and can’t adapt to a shot that’s two stops under.
• Stacking multiple creative LUTs, which compounds the transformations unpredictably.
• Building a LUT from a graded shot with a strong colour cast in it, so the cast is baked into every clip you apply it to.
• Using 17³ for a high-contrast grade and then investigating the banding as if it were a codec problem.

How to do it with LUT Generator

The LUT Generator exports a standard .cube file from your adjustments.

1. Choose a LUT size — 33³ unless the grade is unusually steep.
2. Set lift, gamma and gain for shadows, midtones and highlights.
3. Add saturation and temperature if the look needs them.
4. Export as .cube and apply it after log conversion, not before.

Other colour tools are in the tools directory.

Frequently asked questions

What LUT size should I use?

33³ for most work. 17³ is fine for gentle grades and loads faster; 65³ matters when the grade has steep transitions that a coarser grid would band across.

Where does a LUT go in the pipeline?

After converting log footage to a working space, not before. Applying a display LUT to unconverted log footage produces the classic washed-out or crushed result.

Is a LUT the same as a preset?

No. A LUT is a fixed colour mapping with no parameters; a preset is a set of adjustable settings. A LUT can’t adapt to different exposure, which is why it goes after basic correction.

Final thought

Fix exposure and white balance first, convert from log, then apply the LUT. A LUT applied to the wrong input will always look wrong, however good the grade was.

Try the free LUT Generator