Both photographic film and photographic digital imaging chips are sensitive to the three light primary colors. In other words, both record components of the image i.e. red, green and blue.

Photographic color film displays images using dyes that are the complement of the three light primaries. In other words, the finished developed image using cyan (complement of red), magenta (complement of green), and yellow (complement of blue). Stated differently, the color image displayed on both slide film and negative film is comprised of cyan, magenta and yellow dye. Complement means opposite.

When color images are displayed on a computer or TV screen or projected on a screen, the color image is fractured into its three light primary colors. The image we see is comprised on glowing dots called pixels (picture elements) of red, green and blue. The image is comprised by controlling how much red, green, and blue reaches our eyes by adjusting the intensity of each glowing dot of light.

When it comes to displaying color pictures on paper (prints), the image is fractured into tiny dots of cyan, magenta, and yellow dye / pigment. Again the scheme is to adjust the amount of red, green and blue light that reaches our eyes using dyes that act as filters. Using red, green, and blue tiny dots for prints yields substandard results. This is because the laydown of the colored dots on paper are not individual -- they overlap.

Allow me to explain – The color print is generally viewed via white light illumination from a lamp that is external from the print. Light from this lamp must traverse the dye / pigment which is transparent. The light then hits the white reflective paper and is reflected back towards the viewer. This light again traverses the dye / pigment. In other words, the viewing light makes two transits through the dye / pigment on its way to your eyes.

Now transparent dyes / pigments act as light filters, A light filter passes its name and absorbs the other colors. A cyan filter is a red blocker of light, passing green, and blue. The magenta filter is a green blocker of light passing red, and blue. A yellow filter is blue blocker, passing red, and green. In other words, we view color pictures on paper via the fact that colored dye / pigment stops some colors while passing others. The CMY method for prints on paper works because the dye / pigment stops one color and passes two colors. The results are vivid color pictures on paper.

When dye / pigment overlap, what happens? Magenta + yellow overlapped yields red. Magenta + cyan yields blue. Yellow + cyan yields green. This scheme works for reflective copy like prints on paper. The TV and computer screen uses red, green and blue due to the fact that the individual pixels are not overlapped.

We can make wonderful yellow dye / pigment, fair magenta dye / pigment but poor cyan dye / pigment. The deficiency in our ability to make cyan reduces the contrast of the print on paper. It is necessary to add a black dye dot to prints on paper to bolster contrast. This black dot colorant is called a “Kicker” (kicks up the contrast). Thus, we use the CMYK scheme for prints on paper. We can’t use red, green, blue dye/pigment because if any of the light primary colors are overlayed, the result is black (total absorption) whereas if two of the subtractive primaries CMY are overlayed the result is RGB.

The TV and computer screen works using three sub-pixels red, green, blue, the triad makes one pixel, and they are individual i.e., not overlayed.

Nobody said this stuff is easy!

P.S. Suppose white light is playing on paper coated with a transparent red dye atop a green transparent dye. The top red dye passes red and blocks green and blue. Now red light plays on the green under dye. This light is void of green and blue. The green dye can pass green light, but none is present, it has been absorbed by the red dye above. The result is, no light passes the second dye coat. Together the two dyes have absorbed all thee of the light primary colors. Black is the result if any two primary colors are overlayed. If the dye is a subtractive primary, these pass two colors and stop only one color. A cyan dye stops only red. A magenta dye stops only green. A yellow dye stops only blue.

Overlay Magenta with Yellow. The magenta dye stops green, the yellow dye stops blue. The red light is not stopped, we see red.

In color printing we what to control the intensities of the red, green and blue light that hit the paper and are then reflected to our eye. Cyan dye controls the amount of red we see. Magenta controls the amount of green we see. Yellow controls the amount of blue we see.

When we print with dye on paper, the best way to control how much light is reflected back to our eyes is to use cyan, magenta, and yellow. The subtractive light primaries.

Cyan passes green and blue and blocks red. Magenta passes red and blue and blocks green. Yellow passes red and green and blocks blue. Color film uses CMY – Color prints use CMYK – Digital images projected or on a TV or computer monitor use RGB. Prints on paper made from digital images use CMYK K is the Kicker because cyan dye is nearly impossible to make right.

There are exceptions but most exceptions yield substandard results. Color theory is what you need to study – why not Google the subject?