# Why do we use CMYK color for printing?

shivajikobardan
Homework Statement:
cmyk
Relevant Equations:
n/a
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

Mentor
Homework Statement:: cmyk
Relevant Equations:: n/a

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
The difference is that with light (using RGB or RGBA) the colors are projected, with changes that are additive, but with paints (CMYK) the color changes are subtractive (see https://en.wikipedia.org/wiki/CMYK_color_model).

jim mcnamara
shivajikobardan
The difference is that with light (using RGB or RGBA) the colors are projected, with changes that are additive, but with paints (CMYK) the color changes are subtractive (see https://en.wikipedia.org/wiki/CMYK_color_model).
so how does additive and subtractive ness means we need to use cmyk for printing? i didn't get that thing..

Mentor
so how does additive and subtractive ness means we need to use cmyk for printing? i didn't get that thing..
Did you read the Wikipedia link that Mark posted? Which part is confusing you?

Mentor
When light reflects from a printed page, the ink absorbs (subtracts) certain wavelengths (colors) from the incoming light, to produce the reflected light.