LUT (Look-Up Table)

A LUT takes an input RGB triplet and outputs a new RGB triplet based on a fixed table. That's it. No intelligence, no scene-adaptive logic, no awareness of whether your footage is overexposed by a stop and a half. A 1D LUT adjusts each channel independently — useful for gamma curves and basic contrast adjustments, but unable to cross-channel correct. A 3D LUT maps combinations of all three channels simultaneously, enabling hue shifts, saturation remapping, and the kind of color manipulation people actually associate with "looks." The industry-standard .cube file format stores these 3D mappings as a lattice of points. Common precision levels are 33-point (17x17x17 = 4,913 samples, interpolated for the rest) and 65-point (65x65x65 = 274,625 samples). The difference matters on gradients — a 33-point LUT will band on subtle sky transitions; a 65-point LUT will not. But the file size jumps from ~200 KB to ~5 MB.

A LUT is calibrated to a specific input condition. If you built it on S-Log3 shot at EI 800 with middle gray at 41 IRE, applying it to S-Log3 shot at EI 2000 with middle gray at 34 IRE produces a different image — not the intended one. Exposure offset, white balance variance, even different lens coatings shift the input enough to make the output diverge. This is why on-set DITs create show LUTs per camera and per lighting setup, not one LUT per project. The honest constraint: most commercial LUT packs sold for $49–$149 are tuned to the creator's specific footage and monitoring pipeline. Slapping "Cinematic Teal & Orange Vol. 7" onto your C-Log3 footage rarely produces the thumbnail. You get closer in 30 seconds with a custom primary grade using Lift/Gamma/Gain wheels in DaVinci Resolve than you do cycling through 50 .cube files. LUTs are transfer functions, not creative decisions.