Why the background is not black

The first draft of Seoulnight used a pure black background, and it lasted exactly one night. On an OLED panel in a dark room, saturated glyphs on true black develop a faint bloom at their edges, an effect photographers call halation. Keywords started to shimmer. After twenty minutes the shimmer read as eye strain, and after an hour it read as a headache.

The fix was to lift the background until the halos collapsed, then stop. Lifting too far costs the scheme its depth of night; the whole point is that the window should feel like looking out over the river at 2 a.m. The value that held both properties was a blue-leaning ink, sampled from a long-exposure photograph of the Han River taken from the Dongjak Bridge.

Lifting the background also softened the contrast stack. Body text now sits at 14.5 to 1 against the base, comfortably past the 4.5 to 1 floor the project holds every color to, but no longer at the razor 21 to 1 that pure white on pure black produces. Maximum contrast sounds like a feature until you read under it for six hours; it is the typographic equivalent of high beams in the fog.

One more consequence worth recording: with a blue base, warm colors gained apparent brightness for free. Vermilion and ginkgo yellow both measured the same as before, but sat forward in a way they never did on neutral black. The city taught that trick too. Neon looks brightest over dark water.