Monitors display images with RGB colors, but printers use CMYK inks. Why the difference, and why does it matter for high-quality prints?
Printing with ink or paint relies on subtractive color mixing. CMYK combines cyan, magenta, yellow, and black inks to absorb light, starting from white paper. Adding more ink darkens the result, subtracting reflected light wavelengths to create colors. For true white, the paper remains untouched—no ink can exceed its brightness.
Subtractive systems like CMYK have limitations. Mixing cyan, magenta, and yellow produces a broad spectrum but a narrower color gamut than RGB. Without black ink, combining CMY yields only a muddy gray. That's why black (K) is essential for deep, rich blacks. In specialized cases, spot colors are added for precise brand matches, like a company's logo.
Reflected white light from inked paper selectively bounces wavelengths, which our eyes interpret as color.
Additive color, used in RGB, starts from black and builds light. Red, green, and blue pixels on screens illuminate variably to mix into white light. Full brightness creates white; dimming or turning off pixels produces black or colors. This emitted light reaches our eyes directly, mimicking the rainbow spectrum.
RGB excels on screens with its vast color range, but printing demands CMYK's subtractive approach. Ink on paper can't replicate light emission—mixing RGB inks would yield dull browns, not vibrant hues. Black paper with added light isn't feasible either. Thus, CMYK delivers the continuous color spectrum essential for professional prints, despite its smaller gamut.
