Design Nomenclature / Color
Metamerism
Also called metameric failure, conditional match
Two samples with different spectral curves matching under one illuminant and separating under another. The match was never in the samples — it was in the three cone responses they happened to coincide on. Hence the fabric matched under shop light that splits apart in the street, and the conditional nature of every ink-to-screen approximation.
In practice
Illuminant metamerism is the common case. Observer metamerism — two people who genuinely disagree about a match — is real, and no amount of process fixes it.
Not to be confused with
- Chromatic adaptationThe visual system rescaling its cone responses to the prevailing illuminant, so a white shirt reads white under tungsten and under noon daylight despite radiating quite different spectra. Cameras approximate it as white balance; color management models it with transforms — Bradford, CAT16 — whenever a value crosses between white points.
- Color castAn unwanted hue laid uniformly across an image, usually from an illuminant the capture never corrected for or a profile mismatch on output. The tell is in the neutrals: a cast is nearly invisible in saturated areas and obvious in anything that should be grey, which is why correction starts by finding something known to be neutral.
Origin
Greek meta-, 'beyond', plus meros, 'part': the same whole arrived at from different parts.