What are subtractive primary colors in printing process?
The subtractive primary colors used in printing are cyan, magenta, and yellow. These three colors can be combined to produce a wide range of colors.
There are two main color models used in color reproduction – additive and subtractive. Additive color mixing starts with darkness and adds different colored lights to produce a range of colors. Subtractive color mixing starts with white light and subtracts colors through the use of pigments and dyes to reproduce color.
The primary subtractive colors used in the printing process are cyan, magenta, and yellow. Combining these three primary colors in different ratios allows printers to reproduce a wide range of colors by subtracting wavelengths of light.
What is a primary color?
A primary color is a color that cannot be created by mixing other colors together. In subtractive color mixing, the primary colors are cyan, magenta, and yellow.
These primary colors each absorb or subtract one third of the visible color spectrum:
– Cyan absorbs red light
– Magenta absorbs green light
– Yellow absorbs blue light
By controlling the amount of each primary color, printers can absorb desired amounts of red, blue, and green to reproduce most colors.
The printing industry relies on the subtractive CMY color model rather than the additive RGB model used for light and displays.
Why are cyan, magenta, and yellow the subtractive primaries?
Cyan, magenta, and yellow are chosen as the subtractive primaries because they each align with one third of the visible color spectrum.
Cyan pigment absorbs wavelengths in the red region of the spectrum. Magenta pigment absorbs wavelengths in the green region. Yellow pigment absorbs wavelengths in the blue region.
| Color | Absorbs Wavelengths |
|---|---|
| Cyan | Red |
| Magenta | Green |
| Yellow | Blue |
By controlling the amount of cyan, magenta, and yellow ink deposited, most colors can be reproduced by subtracting the desired amounts of red, green, and blue light.
Alternative primary choices, like red, green, and blue, do not each align with a spectral third and cannot produce as wide a gamut of colors. Cyan, magenta, and yellow allow for optimal subtractive color reproduction.
How are secondary colors produced?
Secondary colors are produced in the CMY model by combining two primary colors in equal amounts. The secondary colors are:
– Red (magenta + yellow)
– Green (cyan + yellow)
– Blue (cyan + magenta)
| Secondary Color | Primaries Combined |
|---|---|
| Red | Magenta + Yellow |
| Green | Cyan + Yellow |
| Blue | Cyan + Magenta |
For example, combining magenta and yellow produces red since magenta absorbs green light and yellow absorbs blue light. Together they absorb green and blue, leaving red.
The secondary colors have the complements of the primary colors, allowing a full range of hues to be produced.
How do printers use CMY to reproduce color images?
Printers use cyan, magenta, and yellow inks, which are deposited onto paper through methods like inkjet or laser printing. The paper starts off as white, which reflects all light equally.
As the printer deposits droplets of cyan, magenta, and yellow inks in tiny dots across the paper, these primary colored dots filter out their corresponding spectral wavelengths.
By controlling the dot size, ink amount, and dot pattern of the three inks, the printer can precisely subtract red, blue and green light to reproduce colors.
During printing, software controls the mixing of the primary colored dots to match the RGB values required to reproduce the colors from the original image.
Four color printing with CMYK model
Many commercial printers add black (K) ink to expand the color range and detail of prints. With four inks – CMYK – printers can produce richer darks and a larger range of colors.
| Color | Absorbs Wavelengths |
|---|---|
| Cyan | Red |
| Magenta | Green |
| Yellow | Blue |
| Black | All Wavelengths |
The black ink allows improved detail for black text and darker colors. The CMY inks then provide nuanced hues and tones.
While cyan, magenta, and yellow remain the key subtractive primaries, black ink improves the efficiency and quality of four color printing.
The light absorption of cyan, magenta, and yellow ink
To understand how the primary subtractive colors reproduce such a wide range of hues, it helps to visualize how they absorb light wavelengths.
Cyan ink absorbs wavelengths in the red region of the light spectrum, around 620-750 nm, while transmitting blue and green light.
Magenta ink absorbs wavelengths in the green region, around 495-570 nm, while transmitting blue and red wavelengths.
Yellow ink absorbs wavelengths in the violet-blue region, around 450-495 nm, while transmitting yellow, orange and red light.
| Color | Absorbs Wavelengths | Transmits Wavelengths |
|---|---|---|
| Cyan | 620-750 nm (Reds) | 450-570 nm (Greens, Blues) |
| Magenta | 495-570 nm (Greens) | 450-495 nm, 570-750 nm (Blues, Reds) |
| Yellow | 450-495 nm (Violet-Blues) | 495-750 nm (Greens, Reds, Oranges) |
By overlaying the primary colors in patterns of dots, the transmitted wavelengths mix additively to reproduce a wide spectrum of hues.
How cyan, magenta and yellow overlay for color mixing
In the CMY model, color mixing is achieved by laying down patterns of tiny dots of each primary color, which together transmit a mix of light wavelengths.
For example, superimposing a dot of magenta over a dot of yellow results in both red light (transmitted by magenta) and green/red light (transmitted by yellow) passing through. The overlay therefore produces a red dot.
Some examples:
| Overlaid Colors | Mix of Transmitted Wavelengths | Resulting Color |
|---|---|---|
| Cyan + Magenta | Blue | Blue |
| Cyan + Yellow | Blue + Green | Green |
| Magenta + Yellow | Red + Green | Red |
By modulating the dot size and density, hundreds of colors can be mixed through selective subtraction and transmission of light.
How black is reproduced in CMYK printing
One limitation of CMY color mixing is that combining cyan, magenta, and yellow pigments will never result in a true black. Because each primary absorbs only one third of the spectrum, combining them leaves unwanted light reflections and produces a muddy dark brown.
For quality black text and strong dark colors, black (K) ink is included in commercial CMYK printing. This adds solid black ink alongside the primaries for accurate blacks.
The black ink also provides more color depth. Without it, reproducing dark shades would require saturating the paper with high densities of all three primaries. Black ink improves print quality while using less ink.
The benefits of the CMY subtractive model
While screens use an RGB additive color model, the CMY subtractive system offers key benefits for printing:
– CMY aligns with the spectral absorption properties of pigments, allowing efficient color reproduction
– The primaries allow controlled absorption of red, green and blue light
– A wide gamut of colors can be produced with just three primary inks
– Black ink further expands range and improves print quality
– Only four inks are needed for full color printing capability
By taking advantage of subtractive color mixing principles, CMY and CMYK printing provides high quality, efficient color reproduction.
Color reproduction challenges with CMY(K)
Though effective, reproducing colors precisely with the CMY(K) model poses some challenges:
– Getting pure cyan, magenta and yellow pigments is difficult – most have secondary absorptions
– Paper and ink reflectance properties affect final color appearance
– Angled lighting can alter color perception
– Colors out of gamut cannot be reproduced by available inks
– Images require color separation and halftoning to CMYK for printing
There are also differences in gamut range and color perception compared to RGB displays. Careful color management is required for accurate cross-media reproduction.
Usage of the CMY and CMYK color models
The CMY subtractive model is used in any printing process that applies colorant pigments or inks to paper. This includes:
– Offset lithography printing
– Inkjet printing
– Laser printing
– Flexography printing
– Dye-sublimation printing
– Silkscreening
Cyan, magenta, yellow, and black inks provide an efficient solution for producing color images and documents. Mixing ratios allow for millions of color reproductions.
Commercial printing uses black ink (CMYK model) for enhanced quality, while home inkjet printers can often print using just the CMY primaries.
Conclusion
The subtractive primary colors used in the printing process are cyan, magenta and yellow. These three inks absorb red, green and blue light respectively to reproduce a wide range of colors through controlled subtractive mixing. The addition of black ink improves quality and color range. While presenting some challenges, CMYK printing offers high quality color reproduction and remains the standard model for applying colorant pigments to print media.
