Why do we use CMYK color for printing?

[shivajikobardan]

I will tell my research that i have done earlier here.

 

CMYK is used for print pieces like brochurers and business cards.

For RGB we need to start on black paper but we can't add light until we reach white because light can't be painted on surface, what does this bold content means to say?

in a monitor, light is being emitted (or added)when you add r,g,b you get white...in ink light is being absorbed(or subtracted) and when you absorb r,g,b you get black

 

if rgb is used, you get strange, muddy, and incorrect colors from printer. (but the question is why)

 

cmy cover most lighter color range quite easily compared to rgb.

 

I want if possible some mathematical representations of this...thanks 

[mistermack]

35 minutes ago, shivajikobardan said:

in a monitor, light is being emitted (or added)when you add r,g,b you get white...in ink light is being absorbed(or subtracted) and when you absorb r,g,b you get black

I don't think that's right. Red ink reflects red light, green reflects green and blue reflects blue. They each absorb the light that isn't r, g, b. So mix r, g and b ink, and white light will find some particles of each colour to reflect off, but will be absorbed by others. So the mix comes back to your eye as a dull neutral greyish, depending on the proportions and strength of the individual absorbtion/reflection characteristics. 

That's my speculation anyway.

[Trurl]

For the pixels on your computer screen the primary colors of red, blue, and green are arbitrary. It is just a reference. You have white 255, 255, 255 as a mixture of all colors and black 0,0,0. All other colors are a variation of that scale.

That is a light source. For printing a different primary scale is used. I don’t know why they picked CMYK. It is just a stating point. I don’t believe you mix these colors like paint. Because as you know from Kindergarten it makes different shades of brown. I was taught that print work is also pixelated like the grays of a news paper. Gray is black pixels spaced further apart.

I am still confused when Photoshop ask which primary colors you want to use. I don’t print much work. But you will see the color scheme in the properties.

[Sensei]

1 hour ago, Trurl said:

I was taught that print work is also pixelated like the grays of a news paper. Gray is black pixels spaced further apart.

Professionally this should be called: dithering.

https://en.wikipedia.org/wiki/Dither

Dithering is also used in ordinary TrueColor, 24 bits, 16 mln (16777216), color computer graphics. From black 0,0,0 to white 255,255,255 there is just 256 shades of gray. If gradient covers large area of the screen, e.g. 1920 width, bands of similar shade are clearly visible (1920/256 = 7.5 pixel). To simulate more colors dithering is used, to exceed 16 mln colors range.

 

Edited April 3, 2022 by Sensei

[Trurl]

@Sensei and others.

 

You know more about the tech aspects than me. I am 20 years behind. I am behind on making modern websites. But that is a future thread.

 

How big is a current jpeg pic? 12 megs? When I was in graphics school web stuff for the computer screen we keep it 72mp. For print it would be increased. We were taught that RGB and CMYK were just different color scales and you change them to match print colors to the desired screen colors. Like how the paint of the car looks different under fluorescent light.

 

I also do not know how the print head mixes colors. And how it breaks the resolution of the pic to colors. But that is complex. It has been perfected over 40 years.

 

I have some graphic experience. Some of the best graphics I have seen is simple black and white. Back in the 80’s people made zines and comics on a black and white photocopiers. One time I had a $5000 color copier that was useless because we didn’t have a $7000 computer interface. I tell this story just to illustrate sometimes the inkjet is overkill for print graphs let alone expensive. More the art side then the science. But we are supposed to fit the science to meet the needs of the art.

 

What type of art is everyone making? I know this is a science forum but STEAM (science, technology, engineering, art, and math).