Colour Science & Perception
what the eye settles, and what it cannot
Generator

A fluorescent source at 5 nm and at 20 nm, sampled

The fine curve is this site's own grid and the stepped one is the same source read at 20 nm. Sampling takes the value at every fourth wavelength and discards the rest, which is what a narrow slit at coarse steps does. Through a reflectance the difference comes out at ΔE00 6.56 — a colour error caused by nothing but the choice of where to look.
A fluorescent source at 5 nm and at 20 nm, sampled. The fine curve is this site's own grid and the stepped one is the same source read at 20 nm. Sampling takes the value at every fourth wavelength and discards the rest, which is what a narrow slit at coarse steps does. Through a reflectance the difference comes out at ΔE00 6.56 — a colour error caused by nothing but the choice of where to look.

Drawn at its defaults, in colour in practice. It reads 5 options and no others: show, obs, source, step, how.

Called by 1 essay

the blast radius of changing it

Matching and measuring

Five nanometres is a choice

Every integral here is taken in five-nanometre steps, and the interval has never had to be defended. Coarsening it to twenty costs daylight two hundredths of a colour difference and a fluorescent tube six and a half — and which way of coarsening is used decides a further factor of six.

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