Why do printers have CMYK ink instead of RYB & black ink?
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RBG is used when light is mixed. Mixing those 3 colors in different ratios allows for the (practical) recreation of any color. The wavelengths of one are added to the wavelengths of the others. CMYK is used when pigments are mixed. A red pigment appears red because it reflects red and all the other wavelengths are absorbed and converted to heat. If you mix a red pigment (which absorbs blue and green) with a blue pigment (which absorbs red and green) and a green pigment (which absorbs red and blue) then theoretically no light would be reflected and it would look black. Now our pigments aren’t perfect, so black (the k in cmyk) is added to get deeper blacks. So which to use depends on what’s making the image: a light source like a pc monitor, or a light reflector like a photographic print.
RBG is used when light is mixed. Mixing those 3 colors in different ratios allows for the (practical) recreation of any color. The wavelengths of one are added to the wavelengths of the others. CMYK is used when pigments are mixed. A red pigment appears red because it reflects red and all the other wavelengths are absorbed and converted to heat. If you mix a red pigment (which absorbs blue and green) with a blue pigment (which absorbs red and green) and a green pigment (which absorbs red and blue) then theoretically no light would be reflected and it would look black. Now our pigments aren’t perfect, so black (the k in cmyk) is added to get deeper blacks. So which to use depends on what’s making the image: a light source like a pc monitor, or a light reflector like a photographic print.
RBG is used when light is mixed. Mixing those 3 colors in different ratios allows for the (practical) recreation of any color. The wavelengths of one are added to the wavelengths of the others. CMYK is used when pigments are mixed. A red pigment appears red because it reflects red and all the other wavelengths are absorbed and converted to heat. If you mix a red pigment (which absorbs blue and green) with a blue pigment (which absorbs red and green) and a green pigment (which absorbs red and blue) then theoretically no light would be reflected and it would look black. Now our pigments aren’t perfect, so black (the k in cmyk) is added to get deeper blacks. So which to use depends on what’s making the image: a light source like a pc monitor, or a light reflector like a photographic print.
White light which comes from the sun contains the full spectrum which can be reproduced by 3 colors of light added together – red, blue, & green. Any color of light can be produced from these 3 colors of light added together. White is all 3 of them. Black is none of them. These 3 colors are used in producing colors of light such as in a TV or movie. This is the additive process. Colors in printing and painting are produced by combining one or more of the 3 primary pigments – cyan, magenta, & yellow. Cyan reflects blue and green light. Magenta reflects red and blue light. Yellow reflects red and green light. Any color of ink or paint can be produced with a correct combination of these 3 pigment colors. This is the subtractive process. To get the best color black is also usually present because it makes for better contrast.
White light which comes from the sun contains the full spectrum which can be reproduced by 3 colors of light added together – red, blue, & green. Any color of light can be produced from these 3 colors of light added together. White is all 3 of them. Black is none of them. These 3 colors are used in producing colors of light such as in a TV or movie. This is the additive process. Colors in printing and painting are produced by combining one or more of the 3 primary pigments – cyan, magenta, & yellow. Cyan reflects blue and green light. Magenta reflects red and blue light. Yellow reflects red and green light. Any color of ink or paint can be produced with a correct combination of these 3 pigment colors. This is the subtractive process. To get the best color black is also usually present because it makes for better contrast.
RGB are the “additive” colors which can recreate all the colors the human eye can see when added to black.
Pigment works by “subtracting” colors from white. You cannot “add” color to white paper as it already reflects all color. Instead you remove colors by applying color-absorbing pigment. Cyan absorbs the color red, yellow absorbs blue, and magenta absorbs green.
This means that to create “green” you have to add all the colors that are not magenta (cyan and yellow). If you instead used green pigment, you would be able to make green with only a single pigment but you would lose the ability to create cyan or yellow (or else the cyan and yellow would be too dark and murky).
Now pigments don’t behave exactly the way we want them to, and they tend to create “layers” and interact with each other. This is why some printers do add extra colors. Black is an example, as it cannot easily be made by mixing all pigments. This tends to produce brown instead, probably due to the fact that the pigments form layers and are somewhat reflective. Ideally only the white paper back would be reflective and the pigments only absorptive.
Now why are red, green, and blue primary colors? Because they correspond to the [3 wavelengths of light that the cones in your retina are sensitive to.](https://i.stack.imgur.com/JtqUU.png) Also many people seem to be unfamiliar with what the color [“true” green](https://www.solidbackgrounds.com/images/1920×1080/1920×1080-bright-green-solid-color-background.jpg) looks like (Among us players call it “lime”). It appears the brightest out of all 3 primary colors simply because that is how the brain perceives it (but it isn’t any brighter in actuality than red or blue). Humans tend to associate the color green with forests and leaves, but this color is usually a desaturated and darker green.
RGB are the “additive” colors which can recreate all the colors the human eye can see when added to black.
Pigment works by “subtracting” colors from white. You cannot “add” color to white paper as it already reflects all color. Instead you remove colors by applying color-absorbing pigment. Cyan absorbs the color red, yellow absorbs blue, and magenta absorbs green.
This means that to create “green” you have to add all the colors that are not magenta (cyan and yellow). If you instead used green pigment, you would be able to make green with only a single pigment but you would lose the ability to create cyan or yellow (or else the cyan and yellow would be too dark and murky).
Now pigments don’t behave exactly the way we want them to, and they tend to create “layers” and interact with each other. This is why some printers do add extra colors. Black is an example, as it cannot easily be made by mixing all pigments. This tends to produce brown instead, probably due to the fact that the pigments form layers and are somewhat reflective. Ideally only the white paper back would be reflective and the pigments only absorptive.
Now why are red, green, and blue primary colors? Because they correspond to the [3 wavelengths of light that the cones in your retina are sensitive to.](https://i.stack.imgur.com/JtqUU.png) Also many people seem to be unfamiliar with what the color [“true” green](https://www.solidbackgrounds.com/images/1920×1080/1920×1080-bright-green-solid-color-background.jpg) looks like (Among us players call it “lime”). It appears the brightest out of all 3 primary colors simply because that is how the brain perceives it (but it isn’t any brighter in actuality than red or blue). Humans tend to associate the color green with forests and leaves, but this color is usually a desaturated and darker green.
White light which comes from the sun contains the full spectrum which can be reproduced by 3 colors of light added together – red, blue, & green. Any color of light can be produced from these 3 colors of light added together. White is all 3 of them. Black is none of them. These 3 colors are used in producing colors of light such as in a TV or movie. This is the additive process. Colors in printing and painting are produced by combining one or more of the 3 primary pigments – cyan, magenta, & yellow. Cyan reflects blue and green light. Magenta reflects red and blue light. Yellow reflects red and green light. Any color of ink or paint can be produced with a correct combination of these 3 pigment colors. This is the subtractive process. To get the best color black is also usually present because it makes for better contrast.
[Here is a color wheel showing many pigments used in painting and printing.](https://painterfactory.com/cfs-file/__key/communityserver-discussions-components-files/19/cwheel06sfsfsfsfs.png) Roughly speaking, if you draw a shape using your chosen pigments, you will be able to make all the colors in that shape, but not out of that shape.
If you draw a triangle around benzimida yellow, quinacridone megenta and pthalo cyan, you will see that your greens, oranges and violets will not be very saturated.
Any three hues is a big compromise, but RBY is an unusually bad choice, because Red and Yellow are close to each other, leaving only B to cover everything from violets to magentas to greens.
In reality, even three ‘normal’ pigments like ultramarine, cadmium red and hansa yellow will be able to reproduce 99% of the colors you see. Very saturated colors are not common. A big reason why people teach color mixing with RBY is that it is easy to control the value of a mixture using yellow and blue since yellow is intrinsically light and blue is intrinsically dark. Good artists can rapidly mix almost any non-saturated color in their environment using these colors.
If you want the biggest color ‘space’ also called a ‘gamut’ you need to choose as many pigments from the periphery of this graph as possible.
Note also that there are not a ton of good options for very saturated green yellows and violets. I am not sure why this is the case, but these colors will potentially be more saturated coming from an emmissive source.
[Here is a color wheel showing many pigments used in painting and printing.](https://painterfactory.com/cfs-file/__key/communityserver-discussions-components-files/19/cwheel06sfsfsfsfs.png) Roughly speaking, if you draw a shape using your chosen pigments, you will be able to make all the colors in that shape, but not out of that shape.
If you draw a triangle around benzimida yellow, quinacridone megenta and pthalo cyan, you will see that your greens, oranges and violets will not be very saturated.
Any three hues is a big compromise, but RBY is an unusually bad choice, because Red and Yellow are close to each other, leaving only B to cover everything from violets to magentas to greens.
In reality, even three ‘normal’ pigments like ultramarine, cadmium red and hansa yellow will be able to reproduce 99% of the colors you see. Very saturated colors are not common. A big reason why people teach color mixing with RBY is that it is easy to control the value of a mixture using yellow and blue since yellow is intrinsically light and blue is intrinsically dark. Good artists can rapidly mix almost any non-saturated color in their environment using these colors.
If you want the biggest color ‘space’ also called a ‘gamut’ you need to choose as many pigments from the periphery of this graph as possible.
Note also that there are not a ton of good options for very saturated green yellows and violets. I am not sure why this is the case, but these colors will potentially be more saturated coming from an emmissive source.
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