Improve performance with a dichotomy

Currently, all the domain is browsed to find the better color point.

It's possible to achieve this using regions instead of browsing all points (L, A, B).

Start by locating the code that browses all L, A, and B color points to select the better color point. Study how the current search works before designing a region-based alternative. Done means the same palette-generation goal is preserved while avoiding exhaustive traversal and improving performance.

Written by the indexing model from the issue text.