Short answer: a 3D LUT is a table that maps every input colour to an output colour. Applying it changes shadows, mid-tones and highlights independently, which is how colour grading works in film post-production. A simple filter usually adds one tint or curve over everything.
What a LUT is
LUT stands for lookup table. A 3D LUT is a cube: its three axes are the red, green and blue values of a pixel, and at each grid point the cube stores the colour that input should become. To grade a pixel, the software finds where its colour sits in the cube and interpolates between the nearest stored points.
Because the mapping is defined per colour, not per image, a single cube can do things a flat tint cannot: push the shadows toward teal while leaving skin tones alone, lift the blacks, roll off the highlights, shift one hue without touching its neighbours.
LUT versus filter
| Simple filter | 3D LUT | |
|---|---|---|
| Operates on | The whole image, usually one adjustment. | Every colour, separately. |
| Shadows and highlights | Move together. | Can move apart. |
| Used in | Quick presets. | Film and video post-production. |
Neither is better in the abstract. A LUT is simply the tool built for a full-colour transform, and it is the one colourists use.
Baked once, offline
Halation's 24 looks — Aurora, Nightfall, Vision, Bleach, Anamorphic, Noir, Flash Night, Funtime, Overexposed, Green Room, Expired, Party, Portrait, Gold, Vivid, Tri-Grain, Tungsten, Meadow, Fade, Clean, Mono, Warm Air, Steel and Amber — are each defined as an ordered list of colour operations and baked once, offline, into a 33×33×33 cube of about 108 KB. The app does not compute a look at run time; it loads the cube.
That has a practical consequence: an iPhone and a Pixel cannot disagree about what a look means, because neither of them works it out. Both read the same file. A reference renderer written separately is the specification, and the shaders on each platform are measured against it — the colour path agrees to within a few units out of 255.
What a cube cannot carry
A cube holds colour. It cannot hold grain, halation or vignetting, because those depend on where a pixel sits and how big the frame is. Those travel as separate parameters and are drawn by the shader — see grain, halation and light leaks.
One slider
Every look has one intensity slider, from nothing to the full effect, so you can stop where the picture still feels like yours. The same 24 looks apply to video clips, re-encoded at the resolution and frame rate your phone recorded.
Cinema colour for photos you already have
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