Vibrance delivered about a third of its nominal effect. Its falloff measured
saturation on scene-linear values, where an ordinary tan reads as 0.78 and
keeps a twentieth of the effect; and its skin guard halved it wherever red led
green led blue — 38 % of the pixels of the gallery's exports, every warm colour
rather than skin. The Vivid presets lean on vibrance, which is why they added
less colour than their values promised.
Saturation is now judged on display-encoded values, the guard covers skin hues
(about 10-50 degrees, not strongly saturated), and the gain is fitted: on 45
Lightroom exports whose only colour setting was Vibrance (about +24), the
measured-to-nominal scale was 1.9 before and 1.08 at a gain of 1.2, so 1.3.