The light

Temperature 2700 K

Used by the last two options. The readout beside the sample says what temperature the page measured back out of whatever spectrum you built, and how far that reading can be trusted.

The material

Refractive index 1.50

Every one of the twenty curves is a flat base plus Gaussian bumps chosen to look right — not a measurement. For the metals that matters most, because a metal’s spectral reflectance is its colour. Drop a measured file on the spectrum plot, or in Data.

The surface

Roughness 0.40

The lobe is chosen on the cards beside the sample. All five are published distributions and all five are reachable.

The geometry

Light from 30° Seen from 20° Between them 0°

Both angles from the surface normal. At 0 and 0 the eye is in the mirror direction and the highlight is at its strongest.

The spectrum

380–780 nm, 81 samples at 5 nm

The colour is a product. Any one of these three curves can be the thing that surprised you, so all three are drawn.

Illuminant D65 Reflectance gold, synthesised What leaves the surface their product

The sample

scaled so a white card here would read Y = 1

sRGB —

CIE L* —

a*, b* —

Jz —

Measured temperature —

Reference for it —

Reflectance —

Inside sRGB —

Against the reference the standard names

—

This material under your source, and the same material under the reference chosen from your source’s own colour temperature. The number between them is a colour difference for this sample. It is not a rendering index and does not characterise the lamp.

Under your source—

— ΔE₀₀

Under its reference—

The chain

How far the colour moves when the curve does

not run

What used to print here

2 withdrawn

A rendering index is a measured sample set, a reference matched to the source, and a stated colour space. This tool holds none of the three, so neither figure is printed — and neither is quietly deleted.

Status

A figure that leans on a stand-in or an absent method is never reported as a published quantity.

Measure the material

Drop a reflectance file Two columns: wavelength in nm, reflectance from 0 to 1. CSV, TSV or whitespace. at least 420–680 nm

The only way the reflectance entry becomes verbatim. Until then the curve is this tool’s invention and the export says so.

Every table and formula a number here rests on

One row per wavelength, and a header that says what it means

0 rows

What each source is used for, and whether it runs

Material Under Light