From “Olo” to RGB and LSD: a guide to colour gamut

In April 2025, headlines rippled through both the scientific world and design communities when researchers claimed to have experienced a colour no human has ever seen before. Using an experimental device nicknamed the Oz Vision System, scientists in California fired precisely controlled laser pulses into the eyes of five volunteers, stimulating individual retina cone cells in ways impossible in nature. The result was a hue the participants described as an intensely saturated blue-green — a colour dubbed “olo” — allegedly outside the gamut of ordinary human experience. But this bold claim is contested: some vision scientists argue it’s better framed as an extreme saturation of a normally perceivable colour rather than a wholly new one. Still, the experiment underscores how our experience of colour is bounded by biology.

Seeing more (or less) than humans: the colourful world of animal vision

Humans are trichromats: our colour vision depends on three types of cone cells — sensitive to long (red), medium (green), and short (blue) wavelengths. This biological setup lets us distinguish millions of hues within the visible spectrum. But in nature, this isn’t the only model.

→ Dogs — and most mammals — are dichromats, possessing only two types of cone cells (often sensitive to blue and green). This means they cannot distinguish certain colours humans can, especially reds and oranges.

→ Bees and some butterflies are trichromats with one receptor tuned to ultraviolet light, opening a part of the spectrum completely invisible to humans. Flowers often exploit this by displaying ultraviolet nectar guides that attract pollinators.

→ Birds, fish, and reptiles frequently have tetrachromatic vision — four or more photoreceptor types — which means they can discriminate even more colours across the visible spectrum and into ultraviolet.

→ Mantis shrimps possess up to 12 photoreceptor types. But having many receptors doesn’t necessarily translate to better discrimination; research suggests mantis shrimps process colour differently, prioritising rapid detection over nuanced perception.

Seeing through other eyes: the camera experiment

One vivid, accessible exploration of animal colour perception in recent years is Netflix’s Life in Colour, where Sir David Attenborough presents a stunning exploration of how animals perceive and use colour for communication, camouflage, and survival. Using specialised camera technology, the series reveals ultraviolet patterns on butterfly wings, polarised signals in mantis shrimp, and other visual cues invisible to humans.

A similar experiment was developed by researchers Vera Vasas, Daniel Hanley and others, which created a camera system that records across a broader range of wavelengths, including ultraviolet, and translates the data into approximations of animal vision. This allows us to “see” through the eyes of bees, birds, and mammals, exposing environments that look radically different from our human perspective.

If you are feeling tech-savvy, you can build the system using the open source code and plans made available by the researchers. 

↑ False-colour footage reveals butterflies’ angle-dependent UV iridescence — a reminder that some of nature’s most expressive colours exist entirely outside human vision. Image credit: Vasas et al. (2024) PLOS Biology.

↑ In honeybee vision, UV-blocking sunscreen shifts from white to yellow, exposing how materials that seem neutral to us can dramatically alter colour signals for other species. Image credit: Vasas et al. (2024) PLOS Biology.

↑ Rendered in avian false colours, northern mockingbirds reveal UV-reflective plumage and a sky rich in ultraviolet — a world where “blue” is only part of the story. Image credit: Vasas et al. (2024) PLOS Biology.

↑ Seen through honeybee vision, a swallowtail caterpillar’s defensive display transforms: UV-reflective yellow markings shift to magenta, turning colour into a high-contrast warning signal for predators that see beyond the human spectrum. Image credit: Vasas et al. (2024) PLOS Biology.

Colour gamut: RGB, CMYK, Pantone and the limits of reproduction

When designers talk about colour, they’re often really talking about colour gamuts — the range of colours that a device or process can reproduce.

↑ Visible color space with approximate RGB, PANTONE®, CMYK coated, and newsprint gamuts. Image credit: Wade Dansby

RGB: the painter of light

RGB (Red-Green-Blue) is an additive colour space. Mixing red, green, and blue light in varying intensities produces a vast range of colours. Our screens — from phones to cinema displays — use RGB because light emitted directly can represent a wider gamut than many print processes.

Typical RGB spaces include:

→ Web-Safe Colour Palette — a relic of old displays designed to avoid dithering; largely obsolete but still referenced in some UI contexts.

→ sRGB — standard for web and most consumer displays.

→Adobe RGB — broader gamut, often used by photographers and high-end monitors.

→ ProPhoto RGB and other wide-gamut spaces — even larger, used in professional imaging workflows.Wider gamuts like Adobe RGB and ProPhoto preserve saturated greens and cyans better in print — but they must be converted carefully for web or smaller-gamut outputs.

These digital gamuts still don’t encompass all perceivable colours. For example, some printed neons won't look very vibrant on photos.

CMYK: print’s constrained spectrum

CMYK (Cyan-Magenta-Yellow-Key/Black) is a subtractive process used for printing. Unlike RGB’s emitted light, CMYK reproduces colour by absorbing certain wavelengths from reflected white light.

Because of ink properties and paper reflectivity, CMYK’s gamut is significantly smaller than RGB’s. That’s why brilliant RGB blues or greens you see on a screen often look dull or muted when printed with standard four-colour process: those hues simply lie outside CMYK’s reproducible space.

This is where print management becomes crucial. Print management is the practice of controlling and standardising colour across digital and physical outputs, ensuring what you see on your screen is as close as possible to what ends up on paper. It involves a combination of colour profiles, calibrated devices, and consistent workflows so that inks, papers, and presses interact predictably. Without it, even technically correct CMYK files can produce inconsistent or disappointing results across different print runs or materials.

To help achieve this, the printing industry relies on FOGRA standards, which provide detailed specifications for preparing files and calibrating presses. These standards define how colours should appear on specific substrates — for example:

→ FOGRA39 for coated paper (glossy or matte finishes)

→ FOGRA52 for uncoated paper (rougher textures like letterheads or stationery)

For colours that still lie outside CMYK’s gamut, designers often turn to Pantone or other spot colour systems. 

Pantone & special inks: extending the gamut

The Pantone Matching System (PMS) uses pre-mixed solid colours (spot colours) to achieve hues that would be impossible in standard CMYK — especially vivid oranges, greens, or fluorescents.

Other special print options include:

→ Metallic and neon inks

→ Varnishes and coatings

→ White or opaque bases on coloured substrates

These techniques let printing flirt with colours beyond CMYK’s natural limits, much as the Oz system explored beyond the limits of natural human vision.