Primary Colors part 2: Optical Mixing

Highlights

• 2024-11-01 11:51 Optical mixing refers to how colors more or less mix on our retinas. There are several different kinds of optical mixing or several different ways that optical mixing takes place.

• 2024-11-01 11:52 little history that takes us back to the times of the Impressionists in France and essentially the late mid to late 1800s. And a person by the name of Ogden Rood, Ogden Rud. He was a physicist. He was also an artist and a color theorist. He wrote a book published in 1879 called Modern Chromatics with Applications to Art and Industry. It was his intention with this book to write in a very clear way, to write a textbook essentially for people who were non scientists and specifically for artists. And it’s all about color mixing. It’s about the properties of light. And he wrote it in a way that summarizes current knowledge at the time about how human color vision operates. And it’s written very plainly in very plain language and not a lot of technical mumble jumble. He writes about Chevrolet, who I’ve spoken about in other episodes in terms of his role in the defining of simultaneous contrast and as well as after images or what he called successive contrast. He talks about Maxwell, James Clerk Maxwell, to be specific, and the spinning discs that he designed to be able to combine different ratios of color that would be spun together and create secondary colors, mix a mixture. And he also talked about Thomas Young and Herman von Helmholtz. Helmholtz, sorry, Helmholtz.

• 2024-11-01 11:57 Rud himself was a painter, and evidently his son, I think his name was Roland, Roland Rood. Roland was also a painter, and he hung around with the Impressionist crew. He reported back to his father that guys like Surat were reading his book and that they actually referred to it as the Bible. Evidently, Rude hated the Impressionist so much that he exclaimed then that he wished he had never written his book. They write, if that’s all I have done for art, I wish I had never written that book.

• 2024-11-01 12:52 It makes me think more like, yes, they’re painting the light, but that Monet, in those studies, he’s interested in a concept known as Color constancy, which I’ll do. That’ll be. It’s kind of a big topic, so that’ll be like something for another podcast. But it’s essentially how human color vision balances itself to the environment with the available light. So, in other words, humans have the capacity to identify a white object under most any light source. We can say that’s white, even though if you were to literally say during sunset, there’s snow on a haystack, no, that’s. That is not white. That’s. That’s like pink. That’s like a shade of red. And I think that. I think that this is evidence that Monet was likely exposed to those thoughts, as well as other things that were coming about, like persistence of vision, which is another one that I’m actually still in the process of learning a lot or learning about myself.

• 2024-11-01 16:28 So those two colors of cyan and yellow form green in my mind because they’re reflecting, in cyan’s case, blue and green wavelengths. Hence cyan. And in yellow’s case, yellow is the product of the reflectance of green and red wavelengths. So the cyan is reflecting green, the yellow is reflecting green. Therefore, there’s more green being reflected back into my eye and perceived by my mind than there are the blue and the red wavelengths that are also coming. So we perceive it as green, but there is some blue and red wavelengths in there that are actually effectively, like, dulling the green. So the green isn’t as vibrant as it could be with the total absence of any blue or red light. And so that kind of speaks to the limitations of subtractive color mixing and hence how subtractive colors are limited in terms of brightness and chromaticity that can be achieved, like on a computer screen or a television. There’s a much greater bucket of colors that we can perceive that can’t be replicated in subtractive color mixing, which points to some of the troubles between working digitally and then printing that digital image out onto a piece of paper. You’re moving from the additive system to the subtractive system.

• 2024-11-01 16:31 Different types of optical color mixing include glazing. So mixing a pigment into a clear or translucent medium and applying that over other colors or color a color or multiple colors, you can have multiple glazes.

• 2024-11-01 16:37 Most famously, pointillism is a type of optical mixing. Also known by a bigger umbrella term called divisionism or chromoluminarianism, whatever that word is, that’s the umbrella term is divisionism. So divisionism, this way of painting, and especially if you’ve looked at like Van Gogh’s work, this pointillism involves like little dots.

• 2024-11-01 16:44 And what Rude is kind of summarizing in the book is to say several things we’ve discussed on the podcast before. The trichromatic theory of color vision, where Thomas Young and Herman von Helmholtz theorized, and I think it later proven, that there are light sensitive cone cells that respond to different wavelengths of white light to produce all the colors that we can see. And they are chiefly sensitive to red, greens and blues. Those are the three types of cone cells. There is some redundancy and overlap in those sensitivities. Cones that are sensitive to the long wavelengths of red, those are what they’re most sensitive to. But they can also detect wavelengths of green and blue as well. It’s just marginal, fractional. And same with the green and same with the blue. So if your green cones are active, you’re able to perceive some of the blue range and the red range with those cones.

• 2024-11-01 17:00 Persistence of vision, like I said, is the opposite of an after effect. So if you stare at something, the classic example is to look at like a dark object on a bright background. And if you close your eyes and even hold your hand over your eyes, you’ll be able to see that image in your mind as this floating image where it’ll continue being the dark object on the bright background.

• 2024-11-01 17:09 One thing about Rood’s book, when he’s talking about Thomas Young’s Helmholtz’s theory of trichromacy, he consistently, throughout the book lists red, green, and violet as the primary colors of light, as opposed to red, green, and blue. Rgb, however, checking. Like Thomas Young’s color triangle that he made, he does list the primaries there as red, green, and blue. So I still have a little bit of research, a little Sherlock Holmes stuff going on to try to determine.

• 2024-11-01 17:10 Our eyes, even though violet is among the shorter wavelengths, our cones are not actually as sensitive to violet. And in fact, the sky would not be blue if our eyes were more sensitive to that lower range. And that the sky would be violet basically instead of blue. Because evidently there’s many more wavelengths of violet scattered in the sky than there are blue ones.

• 2024-11-01 17:10 Homer, how he refers to the color of the ocean as the wine dark sea several times in both the Iliad and the Odyssey.

• 2024-11-02 12:03 So the blue in this case are our synthetic ultramarine blue, which I believe was discovered in the mid-1800s as deposits or leftover stuff on the inside of kilns that they used to bake lime. That could be right or wrong, but yes. So the traditional lapis lazule, Lapis lazuli derived ultramarine blue, which is like the historic stuff from this lapis lazuli stone that mined mainly in Afghanistan, that is a more powdery blue, a lighter blue when it’s ground. Actually, it kind of depends on how it’s ground and the type of blue that you get out of it.

• 2024-11-02 12:11 Part of my thinking on this generated by recent readings of a book called Color for the Sciences by Jan Cohen. In Cohen’s book, in one part, he mentions this idea of scale, and it’s how we think about it. Like a tree at human scale is these pieces like leaves, and then we can see the space between them. But if we were to increase that. Scale, we wouldn’t see if we were. To increase our scale in relationship to that tree, those spaces between the leaves wouldn’t be as apparent. So that’s what’s happening more microscopic level, or even, you know, pointillism or something, or CMYK printing, where it’s maybe not so much microscopic, it’s still smaller than what we’re able to perceive the spaces between them with our human color vision.

• 2024-11-02 12:17 One thing that will become apparent in this series of podcasts too is questions and history related to the relationship between sound and light. Our perception of electromagnetic energy as a wave and our perception of sound as a wave. And then the. The attempts over the centuries to not. Equate the two, but to use the. Terminology of sound and music to describe color and composition in the visual arts and design.