RGB Color Model

The RGB color model creates colors by mixing red, green, and blue light in varying intensities. It is an additive model, so you start from black, meaning no light, and add red, green, and blue, and as the three combine at full strength they produce white. Every color a screen shows is some blend of these three primaries of light. Turn all three off and you get black. Turn red and green up while leaving blue off and you get yellow. Turn everything to maximum and you get white. Because screens emit their own light, RGB is the native model of anything that glows, phones, monitors, televisions, and LED signage. It matches how displays physically work, with tiny red, green, and blue subpixels lit at different levels to fool the eye into seeing a single blended color.

In practice each channel is usually given a value from 0 to 255, so a color is a triplet like 255, 0, 0 for pure red or 0, 0, 0 for black. That range yields roughly sixteen million combinations, the palette often called true color. The same values are commonly written in hexadecimal, the familiar six-digit web codes where FF0000 is red and FFFFFF is white, and hex is simply RGB in another notation. Human vision itself is trichromatic, because our eyes have three types of color-sensitive cone cells, which is part of why a three-primary model reproduces so much of what we can see. RGB, in short, is the color language of the digital world, from web design to photography to video editing.

RGB and CMYK are opposites by design, and knowing how tells you when to use each. RGB is additive, building color by adding light, starting from black and reaching white when red, green, and blue combine. CMYK is subtractive, building color by adding inks that absorb light, starting from white paper and reaching near-black as cyan, magenta, yellow, and key black pile up. RGB suits anything that emits light, meaning screens, while CMYK suits anything that reflects it, meaning print. The two even have a neat relationship, because cyan, magenta, and yellow, CMYK's primaries, are what you get by removing red, green, or blue from white light, so each print primary is the opposite of an RGB one. They are two sides of the same physics, chosen for whether color is emitted or reflected.

The consequence that trips people up is gamut, the range of colors each can reproduce. RGB's additive light can hit vivid, luminous colors that CMYK inks on paper simply cannot, so bright screen greens and electric blues often dull when printed. Convert an RGB image to CMYK for a press and out-of-gamut colors get mapped to the nearest printable ones, sometimes visibly. This is why designers preparing print work in CMYK from the start, or at least soft-proof the conversion, rather than trusting a screen to predict paper. For anything staying on a display, websites, apps, social, and video, RGB is correct and CMYK is irrelevant. Choosing the wrong model, or ignoring the gamut gap between them, is the usual cause of the it-looked-different-on-screen complaint.

Using RGB well starts with matching the model to the destination. If the work will live on screens, author it in RGB and specify colors as RGB triplets or hex codes, and a brand's digital palette should be defined this way so it renders consistently across devices. Be aware of color spaces within RGB, because sRGB is the safe default for the web, while wider spaces like Display P3 can show richer colors on capable screens but may look off where they are not supported. Keep values consistent across your assets so the same blue is the same blue everywhere. And when a design must also be printed, plan the CMYK conversion deliberately rather than exporting and hoping, because the two models do not share a gamut and a surprise on paper is otherwise almost guaranteed.

The failures are mostly mismatches. Teams design in RGB and send files straight to a printer without converting or proofing, then blame the press for colors that were never printable. They mix color spaces, tagging some assets sRGB and others P3, so the same hue shifts between screens. They specify a brand color in hex alone and have nothing defined for print. Or they assume a screen preview predicts a printed result exactly, ignoring the gamut gap. The discipline is straightforward. Use RGB for emitted-light media, define colors precisely in a known color space, keep them consistent across assets, and convert to CMYK thoughtfully whenever the same design crosses from screen to paper.

The RGB model formalizes trichromatic color theory, the finding that three color signals can reproduce human color vision, into the red, green, and blue primaries used by electronic displays.

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