Verb
(transitive, mathematics, computing) To convert (a continuous space) into an equivalent discrete space, often for the purposes of easier calculation.
(transitive, broadly) To represent (any spectrum of reality) as a set of discrete categories or classes; to categorize (a spectral aspect of reality) by lumping together some of its finer distinctions.
A rainbow truly contains thousands of color values but can usually be discretized by human sentience into bands of primary and secondary colors.