How a lookup table changes an image
A lookup table, or LUT, is a set of instructions for replacing color values. For each pixel, software reads its original red, green, and blue values, consults the table, and outputs new values. A pixel that began as a muted blue, for example, might be mapped to a deeper blue; a range of pale colors might be shifted warmer.
Because the same mapping is applied across the image, a LUT can give footage or photographs a consistent color treatment. More complex tables account for combinations of red, green, and blue rather than adjusting each channel separately, allowing more nuanced shifts.
The filter becomes permanent when it is baked in
While editing, a LUT is usually an instruction the software can apply, remove, or swap without changing the original pixels. But when the edited image is exported with the effect included, the transformed color values are written into the file. The look is then effectively permanent in that copy: removing it requires the original or a separate unedited version.
That distinction makes LUTs useful in production. An editor can reuse one mapping across many shots, then decide at export whether to keep the result adjustable or bake it into the final image.
A LUT cannot know what a pixel represents
A table responds to color values, not meaning. It cannot tell whether a patch of blue is sky, fabric, or a reflection, so the same input color receives the same treatment wherever it appears. If that shift makes one part of a scene look wrong, an editor may need masks or other selective adjustments in addition to the LUT.
