<https://forum.reapermini.com/index.php?/topic/51585-reaperites-i-give-you-my-colour-comparator-spreadsheet/#comment-769890>
<http://schema.org/text>
"The reflected color of light from a sample approaches the color reflected from an infinitely thick sample asymptotically. For optically thick paints, you really don't need a particularly thick sample. \n  \nPigments don't reflect on a single frequency, and not usually even on a narrow single peak. Given pure black-body illumination, you'll normally see multiple wide peaks for a given pigment, and a given color will be even more complex. Frequency (singular) is not a very useful descriptor of paint color. \n  \nAll that said, IME (and I do use a calibrated monitor), online samples are nearly useless. There are several contributors to that: \n  \n1) There is no way to know what light was used to generate the original online sample. It could be generated under lights anywhere between 3500K and 8000K (tungsten to north light), which will result in wildly different overall results. \n  \n2) Further, there's no way to know what the color rendering index of the original light was, or where the spikes in the light might have been. And since pigments preferentially reflect narrow frequency bands, CRI and the precise position of the peaks is crucial. \n  \n3) Online swatches are viewed on an emissive monitor, not a reflective surface. That radically changes the experience. \n  \n4) Even if all of that were perfect and the customer's monitor were calibrated perfectly, there's no way to know what light the final figure will be seen under, which has all of the CRI and color temperature problems as the original scan/swatch. \n  \n5) Finally, I use very few unmixed colors. And simply knowing the color of the paint says only something, not everything about what a mix will look like, which depends on the precise pigments and ratios used, not the aggregate color of the paint. \n  \nNone of which is to say that your work is useless, but simply that its use is limited. \n"
<https://forum.reapermini.com/index.php?/topic/51585-reaperites-i-give-you-my-colour-comparator-spreadsheet/#comment-768885>