Red Yellow Blue was used in early printing because that was the best they knew at the time. Technology advanced, and printing color images switched to using magenta and cyan to get a wider, more accurate range of colors.
Our eyes see three basic colors of light: Red, Green, and Blue. Cyan pigment only absorbs one color from light, Red; this leaves behind Blue and Green. Magenta pigment absorbs only Green. Yellow pigment absorbs Blue. Mix those three in varying combinations and you can get every color the human eye can perceive. (Technically you don’t need Black in CMYK, but it takes a lot of CMY to get a good, dark Black.)
In contrast, Red Yellow and Blue can only be mixed to *most* visible colors, but there are some that are simply not possible to create with those three as your “primary” colors.
The reason Yellow “gets a pass” is because it is a primary color in color schemes for both subtractive light and traditional art.
So why did we use Red Yellow Blue for so long? Because (a) for a long time we didn’t know enough about light to know Cyan and Magenta are better primaries, and (b) Cyan and Magenta pigments are hard to make, requiring (relatively) modern processes.
CMYK does not account for the color white. It does not need to because it is designed to be used for color renditions to be printed on white paper; white just means “no ink”. With CMYK, the color produced by combining all colors to full saturation is a dark brown. With printed inks, greater application of ink reduces light reflected and results in a darker image. This is noteworthy because it’s the opposite with light renditions. On to RGB!
RGB, on the other hand, does not account for the color black. It does not need to because it is designed to be used for color renditions to be produced with light; black just means “no light”. With RGB, the color produced by combining all colors of light is white. This is why RGB is used for computer screens. It can render white. CMYK cannot. For PC display hardware, black backgrounds do not reflect light emanating from nearby lit pixels, so black is an ideal color for the screen’s backing. It can display black by simply not lighting a pixel, and the pixel will hold black well enough because it reflects minimal light from the black backing. If the backing were right (so an off pixel displayed white), the white would reflect colors of nearby lit pixels and not appear white at all.
Thus, CMYK for printing and RGB for light renditions that require production of the color white.
>**EDIT:** to clarify my questions a bit, I’m not asking about the difference between additive/subtractive color models which has already been covered in other threads on this sub. I’m asking why/how the older Red-Yellow-Blue model in art/printing was updated to Cyan-Magenta-Yellow, which is the current standard
Oh but you are. It has -everything- to do with subtractive color models.
Blue, Yellow, Green, and Red inks were among the first to come out, so they got used in microdotting early on. The big problem with these four colors is that you can’t make most of the colors (because of subtractive color that pigmentation works on); this made things look grainy, lacking color depth. It’s one reason why comics before a certain time look like crap.
Once cheaper dyes and computers became ubiquitous in publishing, they developed the CYMK coding model so that computer-information could easily be shifted into color printing. CYMK doesn’t have much translating needed to convert from RGB (additive color, which is how graphics is stored and processed in most computer use), and so that also became attractive as What You See Is What You Get (WYSIWYG) publishing became the norm.
The reason black is added as a fourth color is simply because of cost: Black ink is FAR cheaper, and blacker, than if you made black out of the three color inks.
As for what was previously used, there were various color models, each with advantages and disadvantages.
Four-color used Red, Blue, Yellow, Green, and Black. It did not mix Yellow and Blue to get Green ink because that would be expensive–it was cheaper just to use Green ink. Because it used those four primary colors, this was called ‘Four-color printing’ and was the norm until inexpensive Cyan and Magenta inks became available and computers were the norm.
Another form of color printing used was ‘Spot Color’ where two or three colors of ink were used. This could be used to get exactly the color you wanted, but you’d only get that color, and usually the second color was black. This is considerably less expensive than Four-color, but it’s not the least expensive option.
After this, you have good’ol Monochrome. Usually, black, but sometimes a different color, that’s when they use one ink and one ink only.
Unless you know what you’re looking for, you might think a given book is full color throughout, but it actually might not be. It might be using a combination of four CYMK pages interleaved with spot-color pages to give the illusion of full color, while costing a lot less to publish. This might explain why your favorite gaming book doesn’t have the table you want on the page you’d think it should be (because it uses a different spot-color than the page you’d think it be on) or why it seems some sections of that book have full color art, and then long sections with only text, but those text pages have that metallic gold lettering you ever see on the full color pages (CYMK doesn’t have metallic sheen or similar things)
>Why did cyan and magenta replace blue and red as the standard primaries in color pigments?
Painters used “true” blue and red because 1) the pigments are easier to obtain in nature 2) people were still learning how color works 3) R and B were good enough to recreate the majority of colors around them. The range of missing colors (like magenta, bright purples, oranges etc) arent often needed in paintings of natural subjects.
>What exactly makes CMY(K) superior to the RYB model?
It’s “superior” because you can create more colors with that system. As others have said- you can mix M with Y and C to make R and B and many other colors you can’t get with RYB. RYB makes “muddier” colors. I put superior in quotes because many painters still use an RYB palette, because it’s easier to make those duller, earthier colors. Modern printers need to make ALL the colors though.
>And why did yellow stay the same when the other two were updated?
They just had yellow correct from the beginning. Again- they work as primaries for many many colors. Just needed a bit of refining to get more.
RYB has a smaller gamut than CMY, but it might be easier for painters using pigments that are more opaque and difficult to mix. Dyes being mixed by computers are much more precise, far beyond what a painter can handle on their palette.
Ultimately it is just a less capable model which has a lot of institutional inertia behind it.