Talk:Grassmann's laws (color science)

Grassman's Laws (plural)

This should really be Grassman's Laws (plural), shouldn't it? Most credible sources I can find describe four laws. Notes from a class at University of Houston, many hits on google scholar etc. The laws are stated with varying degrees of mathematic notation across sources, but the laws say 1. You need three colors that are linearly independent 2. A change in a component color will change the mixture 3. Lights stimulate independently 4. Proportional intensity. It would be nice to cite Grassman's original formulation (which I can't find at the moment).Maneesh (talk) 20:07, 31 December 2017 (UTC)

Yes, I agree. This book has a good set of statements attributed to Grassman (probably not quite original form, which was in German). Dicklyon (talk) 20:24, 31 December 2017 (UTC)

Also I think this should really be perception or psychology, not optics. The first sentence of the article makes that clear and this isn't about the behavior of light beams as it is as about what happens when they hit the retina.Maneesh (talk) 22:30, 31 December 2017 (UTC)

As the book I linked says, "All modern colorimetry is based upon the principle stated in the third Grassman law". This is essentially the principle of colors being a 3D linear subspace of spectral power space, corresponding to the retina having three types of receptors with different linear spectral weightings, even though everything that comes after, including the response of those receptor cells, is nonlinear. That is, Grassman's laws are really about the physical optics end of the color vision process, more than the neural/psych end of the chain. A better more neutral disambiguator would be something like "(color science)". Dicklyon (talk) 23:06, 31 December 2017 (UTC)

Abney's Law

The link seems broken.

More importantly, Abney's Law has a superficial similarity to Grassmann's 4th law, but in fact it is quite different. I suggest removing the reference. Wandell (talk) 04:24, 20 December 2023 (UTC)