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romxza OP t1_j34jhnr wrote

Reply to comment by Prestigious_Carpet29 in How close does one need to bring two coloured lights together to perceive a compound colour effect? by romxza

Nice, all this make sense and these answers were pretty close to describing in some detail what I was trying to look more into. Thank you!

I was also naively hoping for an undeniable elegant and satisfying practical demonstration of two different coloured lines kissing and boom, new colour, without fakery. I suppose things like the psychological aspect of colour perception will also get in the way to make it that level of satisfying. I haven't tried the computer graphic idea yet, but I'll give it a shot.

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dmmaus t1_j359y61 wrote

It's important to understand that colour sensation is entirely psychophysical. The colours we sense are a product of the construction of our eyes and nervous systems - they don't really exist outside the context of a human observer (or an observer with the same visual architecture).

A spectrometer can easily tell the difference between (light of wavelength 580nm) and (mix of light with wavelengths 480nm and 650nm). There is a physical difference. But human vision cannot tell the difference - our brains sense both these as "yellow". Which one is really yellow? Neither. "Yellow" has no physical reality outside a human brain - it's our label for a sensation that we have.

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Prestigious_Carpet29 t1_j68qfaf wrote

Yes.

See metamerism

This is also why paint-matching can be a huge problem. You can get two paints that look the same colour under one lightsource (eg. daylight) but are visibly different under a different source (e.g. fluorescent, or sodium streetlights)

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