Look Up Tables (LUTs)

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A Look Up Table (LUT) is a pre-made list of values used to quickly find results instead of calculating them from scratch. In simple terms: instead of running a complex formula every time, the computer just looks up the answer in a table.

This is often much faster, especially for repeated calculations or real-time applications.

Usecases

Photo & Video

In photography and video, LUTs are used to apply a consistent color style or “look” to footage. Think of it as a preset that instantly changes tones, contrast, and color balance. Similar to a filter, but more precise.

You can find free and paid LUT packs by searching online for color grading luts.

Force Feedback

In sim racing, LUTs can also improve Force Feedback (FFB). For wheelbases, an FFB LUT maps the actual forces your wheel produces to the intended forces from the game, correcting for hardware quirks and making steering feel more accurate.

For Assetto Corsa, the most common tool is LUT Generator for AC by Akis, which sends test forces to your wheel, measures its response, and generates a custom LUT.

Details

A LUT is usually stored as an array or table of precomputed results. The process is called direct addressing, where instead of running the function, the program uses the input as an index to instantly retrieve the output.

This method trades memory for speed:

• Pros: Much faster than computing values in real time, especially for complex math or input/output operations.
• Cons: Requires storage space for the table and is fixed to the precomputed values.

In performance-critical environments like real-time graphics or physics simulation, LUTs are often used for functions such as trigonometry, gamma correction, and force mapping.