Measuring Metamerism
The best-known measure of metamerism is the Color Rendering Index (CRI), which is a linear function of the mean Euclidean distance between the test and reference spectral reflectance vectors in the CIE 1964 color space. A newer measure, for daylight simulators, is the MI, CIE Metamerism Index which is derived by calculating the mean color difference of eight metamers (five in the visible spectrum and three in the ultraviolet range) in CIELAB or CIELUV. The salient difference between CRI and MI is the color space used to calculate the color difference, the one used in CRI being obsolete and not perceptually uniform.
MI can be decomposed into MIvis and MIUV if only part of the spectrum is being considered. The numerical result can be interpreted by rounding into one of five letter categories:
| Category | MI (CIELAB) | MI (CIELUV) |
|---|---|---|
| A | <0.25 | <0.32 |
| B | 0.25–0.5 | 0.32–0.65 |
| C | 0.5–1.0 | 0.65–1.3 |
| D | 1.0–2.0 | 1.3–2.6 |
| E | >2.0 | >2.6 |
Read more about this topic: Metamerism (color)
Famous quotes containing the word measuring:
“... there is no way of measuring the damage to a society when a whole texture of humanity is kept from realizing its own power, when the woman architect who might have reinvented our cities sits barely literate in a semilegal sweatshop on the Texas- Mexican border, when women who should be founding colleges must work their entire lives as domestics ...”
—Adrienne Rich (b. 1929)