LUT Previewer

Knowledge Base

What a .cube LUT Actually Is

A .cube file is a 3D lookup table: a grid of pre-computed output colors for a fixed number of input color combinations (commonly 17×17×17 or 33×33×33). To grade a real pixel that falls between grid points, a proper LUT engine has to interpolate between the eight nearest grid corners. This tool does that trilinear interpolation for real, the same math a color grading application uses, rather than faking the look with a CSS filter.

Why Intensity Control Matters

Many creative LUTs are designed to be applied at less than 100% strength, blended with the original image to taste. The intensity slider linearly blends between your untouched upload and the fully-graded result, which is exactly how "LUT opacity" works inside a real NLE or grading tool.

Where to Get .cube Files

Camera manufacturers (Sony, Panasonic, Blackmagic, RED) publish free log-to-Rec.709 conversion LUTs for their cameras, and many colorists release free creative LUT packs, search "[your camera model] LUT download" or "free cinematic LUT pack .cube" to find some to try here.

FAQ

Q: Does this support 1D LUTs?
A: No. This tool reads 3D LUTs only (the `LUT_3D_SIZE` format most creative and camera LUTs use). A 1D-only .cube file will show an error.

Q: My image looks wrong after applying the LUT, why?
A: Most creative LUTs expect Rec.709/sRGB footage as input. If your source is log or RAW footage viewed without its own conversion first, the LUT's math will be applied to the wrong starting point and the result will look off, convert to Rec.709 first, or use the camera manufacturer's log-to-709 LUT before a creative look LUT.

Applying a LUT without ruining the image

A LUT is a lookup table mapping every input colour to an output colour. Because the mapping is fixed, a LUT knows nothing about your particular shot. It cannot compensate for an image being a stop under, and applying one to a badly exposed frame produces a badly exposed frame in a different colour.

Two different things both get called LUTs. A technical or conversion LUT translates footage from a camera's log recording into standard display colour, and belongs first in the chain. A creative or look LUT applies a style on top. Applying a creative LUT directly to log footage without converting first gives a flat, washed result, which is the single most common mistake with them.

Balance the image before the LUT, not after. Set exposure and white balance so the shot looks correct and neutral, then apply the look. Working the other way means you are correcting through the LUT, and every adjustment fights a transformation already applied. This is also why the same LUT looks different on two shots from the same scene if their white balance drifted.

Intensity below 100 percent is a legitimate tool rather than an admission of failure. Most creative LUTs are built strong so their effect is obvious in a preview. Somewhere between 40 and 70 percent often gives the intended character while keeping skin tones believable, and skin is the first place an overcooked look shows.

Vocabulary

LUT. Short for lookup table. A file mapping input colours to output colours, used to apply a colour transformation consistently. A 3D LUT such as a .cube file maps combinations of red, green and blue together rather than each channel separately.

Log footage. Video recorded with a curve preserving detail across a very wide brightness range, at the cost of looking flat and grey straight from the camera. Intended to be converted to display colour later, which is what a technical LUT does.

Rec.709. The standard colour space for high definition television and most online video. The target most footage ends up in, and what a technical LUT converts log recordings into.

Clipping. Where values pass the maximum a format can store and detail is lost permanently. A LUT pushing highlights past the limit clips them, and no later adjustment recovers what was discarded.