How do our colour-blind cones achieve colour vision?
theneurosphere.com
theneurosphere.com
An alternative title to this article could be "how spaceless numbers achieve defining space"? Like you just have a basis, and this defines space. Mind blown. Really, how do these magnets work?
No. Paint is not light, and has physical properties that constrain what you can do with them. Some colors just don't mix well together, so you'll find recommendation on what exact type of pigment work best for specific mixes.
Perceivable colors are a three-dimensional space, and colors you can make out of three primaries are a three-dimensional space, but they're different shapes. Mixing primary colors is a way of interpolating between them linearly, and the space of perceivable colors doesn't have convenient linear edges.
Here's an example. Your printer has cyan, magenta, and yellow ink (and also black for convenience). So it can print any color, right? It should be able to print bright lime green, something that looks like RGB #00ff00, right?
No, in fact, you can't print that color without "spot color" ink. When you mix cyan and yellow to make green, it will necessarily get darker. If you use enough cyan and yellow to get full-saturation green, it'll be too dark. If you use less ink, it won't be saturated enough.
Lime green is outside of the CMYK gamut. Similarly, the deep cyan you'd get by printing with lots of cyan ink is outside of the RGB gamut.
Where did I try to make this point? My issue is with the quality, not the subject. As pluteoid remarked, this is not a very good article, and fairly long-winded with regard to its content.
There has been many submissions of articles regarding color theory and its relation to psychology, design and physics, many of which are very interesting, and make you learn useful and applicable knowledge. For instance, you may learn how to write an imagemagick script to get the dichromat version of an image.
If each of the values of a three-dimensional coordinate pair encoded frequency, that triplet could carry information about a mixture of up to three colors. This would require sensors that are not "color blind".
I think that's a good summary of the article's point.
1) The RGB palette used in monitors most certainly does not span the whole gamut of human vision. Not even the wide-gamut monitors used professionally can do that yet.
2) The diagram showing each cone type's peak spectral sensitivity is a bit misleading, too. The M- and L-cones are colored red and green, but if you notice carefully, their peaks lie in the green/yellow area, so characterizing them as red/green is misleading. And "each of our cones seeing a primary colour (blue, green, or red)" is flat-out wrong. Every cone fires in proportion to its overlap. The author clarifies this later, but it's best to tell people the caveats up front. Continually referring to "primary" colors is adding to the confusion here.
3) WhIle they did cite an article pointing out that ratio-computing cells exist in the retina, it does NOT follow that "it is the main source of information that the brain has to help it identify the wavelengths of light". The paper itself only talks about spectral separation in retinal cells pre-brain. I don't know where the author got the idea that ratios are the main source of info sent to the brain. Amplitude information is sent, as well.
I thought printers typically use CMYK (4 inks) or CMYKOG (6 inks).
OP is incorrect; no tristimulus based (RGB or CMY) combination can reproduce the spectral locus without resorting to imaginary colour primaries. Imaginary primaries cannot be reproduced in reality, and as such, “all the colours we see” is “all the colours we may see from the printer.”
If the errors pointed out by above posters are valid, they should really go over to the OP's blog and post them so she can correct the post.