A LUT, or lookup table, is a tool used in computer science and video production to simplify complex computations and color grading processes. In computer science, a LUT is an array that replaces runtime computation with a simpler array indexing operation, in a process termed as direct addressing. Before the advent of computers, lookup tables of values were used to speed up hand calculations of complex functions, such as in trigonometry, logarithms, and statistical density functions. In video production, LUTs are used to transform color input values to desired output values, essentially acting as filters that can be dropped onto images to achieve a desired outcome. There are several different types of LUTs available, including calibration, transform, viewing, 1D, and 3D LUTs. Creative LUTs are used to add a specific look to footage, while conversion LUTs are used to convert flat, desaturated footage back into a typical color space. LUTs are used through standard NLEs or coloring software like DaVinci Resolve or Speedgrade.