[userbinator]

After checking each of the 256 cells, the cell with the lowest difference is chosen.

This is essentially the fundamental operation of a vector quantizer codec, which was popular in the early days of lossy video compression due to its low processing requirements. The fact that this term doesn't appear in the article means the author has independently discovered and reinvented this theory, which is itself quite impressive.

[flykespice]

Those kinds of things can be figured with intuition, and it's more productive this way than spending time looking through academic articles online