Global shadows / highlights on OKLab lightness: L' = L + s·L(1−L)² + h·L²(1−L), with L clamped
to [0, 1] inside the weights. The shadow term peaks at L = 1/3, the highlight term at 2/3;
black, white and HDR values above white do not move, and the curve stays monotone for
|s|, |h| ≤ 1. (A local, detail-preserving version is tier B "brilliance".)
Global shadows / highlights on OKLab lightness: L' = L + s·L(1−L)² + h·L²(1−L), with L clamped to [0, 1] inside the weights. The shadow term peaks at L = 1/3, the highlight term at 2/3; black, white and HDR values above white do not move, and the curve stays monotone for |s|, |h| ≤ 1. (A local, detail-preserving version is tier B "brilliance".)