Notes:
The lookup table tool allows you to show a greyscale image with colors.
These can reflect the real wavelength or they can be choosen arbitrary to allow you to recognice better the details you want to see.
How does it work?
An 8 bit image contains 256 values from 0 to 255. With a lookup table each value is mapped to a color and each pixel in the image that has this intensity value is shown in the associated color.
The lookup table “hilo” is especially useful. It displays 0 intensities in blue. Maximum intensities in red and everything between in the normal greyscale.
Use it when you adjust brightness / contrast.