In computer science, a look up table(LUT) is an array that replaces runtime computation with a simpler array indexing operation. It can help us save the computation time and accelerate the process.
In image processing, we can use LUT to store the RGB values and modify them to new RGB values by changing the hue, saturation and brightness values. And we can qickly change color style or do color grading from source image by using LUT. The image below is a sample of 3D LUTs, 3D LUTs are based on a three-dimensional Cube with 16777216(256x256x256)colors, which have ability to change a given RGB output value based on RGB input value change. The images below show the sample of 3D LUT with VSCOX KU4 preset.