Why We Never Agree on Color—And the Science That Can Finally Settle the Argument

It started, as modern arguments often do, with a dress. In 2015, a photograph of a simple garment cleaved the internet in two. Was it blue and black, or white and gold? Families were divided, friendships strained. The debate raged not because anyone was lying, but because, for the first time on a global scale, we were confronted with a startling truth: our perception of color is fundamentally unreliable.

This phenomenon, dubbed “#TheDress,” was a viral symptom of a much older and deeper problem that has vexed artists, scientists, and manufacturers for centuries. When you and I look at the same can of Coca-Cola red, are we truly seeing the same thing? If you take a cushion from your sofa to the paint store for a perfect match, why does the color on your wall end up looking stubbornly… off?

The unsettling answer is that color doesn’t exist out there in the world in the way we think it does. It is a fabrication, a complex negotiation between the physics of light, the chemistry of a surface, and the unique, idiosyncratic biology of our own eyes and brains. For most of human history, this subjectivity was simply a fact of life. But in a world of global brands, precision manufacturing, and digital design, “close enough” is a recipe for disaster. What we needed was a way to pull color out of the realm of opinion and into the world of objective fact. This is the story of how we did it.

Ordering the Rainbow

Our journey to quantify color begins, as much of modern physics does, in a darkened room with Isaac Newton. In 1666, by passing a beam of sunlight through a prism, Newton demonstrated that white light was not pure but a composite of all the colors of the rainbow. He proved that color was an intrinsic property of light itself. An object, therefore, has no color of its own; a “red” book is simply a book whose surface is particularly good at absorbing all wavelengths of light except for those our brain interprets as red.

Newton had laid the foundation, but a chasm remained between this physical reality and our human experience. How could you measure the infinite variations of color in a standardized way? For over two centuries, this question remained unanswered. Then, in the 1920s, a series of ingenious experiments by researchers W. David Wright and John Guild finally provided the key. They had subjects attempt to match every color of the visible spectrum by mixing precise amounts of red, green, and blue light.

The averaged results of these thousands of trials gave birth to the 1931 CIE Standard Observer. It was a monumental achievement: a mathematical definition of the average human’s color perception. For the first time, a color could be described not with a poetic name like “cerulean blue,” but with a precise set of three coordinates: X, Y, and Z. The world of colorimetry was born, and with it, the first map of all visible colors.

The Flaw in the Map

The CIE 1931 XYZ color space was a revolutionary tool, but it had a strange and frustrating flaw. The map wasn’t drawn to scale with our perception. On this map, a one-inch step in the green region might represent a barely noticeable color shift, while the same one-inch step in the blue region could represent a dramatic, obvious difference. This lack of perceptual uniformity made it incredibly difficult to answer a simple, critical question: “How different are these two colors?”

Decades of work were spent trying to warp and stretch the XYZ map into a shape that better reflected how we actually see. The result, now the gold standard in nearly every industry, is a space called CIELAB (or more formally, $L^*a^b^$).

Imagine CIELAB as a three-dimensional sphere. The vertical axis, $L^$, represents lightness from pure black (0) to pure white (100). The $a^$ axis runs from green to red, and the $b^*$ axis runs from blue to yellow. Any color the human eye can perceive can be plotted as a single point in this space.

This new map was revolutionary because it was largely perceptually uniform. Now, the geometric distance between any two points in the space directly corresponded to the perceived difference between the two colors. This distance was given a name: Delta-E ($\Delta E$). It is the single most important number in the world of professional color. A $\Delta E$ of less than 1.0 is generally considered imperceptible, the threshold of a perfect match. A brand can now tell its printer, “Our logo must be reproduced with a $\Delta E$ of less than 2.0 from our official standard.” The argument is over. The standard is absolute.

The Color’s Fingerprint

With a reliable map (CIELAB) and a unit of distance ($\Delta E$), the final piece of the puzzle was getting an accurate reading of the terrain. How do you pinpoint a color’s exact coordinates?

For many years, the primary tool was the colorimeter. A colorimeter works much like the experiments of Wright and Guild, using red, green, and blue filters to measure light and calculate a color’s coordinates. It’s a good tool, but it has the same limitation as our own eyes: it can be tricked by a phenomenon called metamerism. This is where two objects with different chemical makeups (and thus, different ways of reflecting light) appear to be the same color under one type of lighting, but look noticeably different under another. They are metameric pairs—impostors that a colorimeter can’t unmask.

To defeat this phantom, a more powerful tool was needed. This is the spectrophotometer.

Instead of using just three filters, a spectrophotometer ignores our human-like RGB vision entirely. It measures the light reflecting off a surface at dozens of points across the entire visible spectrum, from deep violet to far red. The result is a unique graph called a spectral reflectance curve. This curve is the color’s true, unalterable identity—its DNA.

This spectral curve is the ultimate source of truth. From this “fingerprint,” a device can mathematically calculate what the color’s CIELAB coordinates would be under any lighting condition imaginable—daylight, fluorescent office light, warm incandescent light—and predict with certainty whether it will match another color. It can see the “impostor” colors for what they are by comparing their underlying DNA, not just their superficial appearance.

The Detective in Your Pocket

For decades, spectrophotometers were the size of a shoebox, cost tens ofthousands of dollars, and remained tethered to laboratory benches. But just as computers shrank from rooms to desktops to our pockets, so too has this powerful technology. The perfect exemplar of this shift is a device like the Nix Spectro L Spectrophotometer and Densitometer.

This small, robust cylinder is a marvel of miniaturization. When placed on a surface, it illuminates it with its own calibrated, full-spectrum light source. Its nine-channel sensor reads the reflected light, and through a process of algorithmic upscaling, generates a 31-point spectral curve—a high-resolution fingerprint of the color. It then performs the CIELAB and $\Delta E$ calculations instantly, sending the objective data to a smartphone app.

But its true cleverness lies in how it handles the messy realities of the physical world. Consider paper. To make paper appear whiter and brighter, manufacturers add chemicals called Optical Brightening Agents (OBAs). These agents are like color tricksters; they absorb invisible ultraviolet (UV) light and re-emit it as visible blue light, making the paper seem “whiter than white.” This UV fluorescence can wreak havoc on color measurements.

This is where the ISO 13655 standard, and the Nix Spectro L’s M0, M1, and M2 measurement modes, become crucial. Think of them as a detective’s special flashlights for interrogating a surface:

• M2 (UV-Cut): This mode uses a light source with the UV filtered out. It measures only the true color of the paper and ink, ignoring the OBA trickery.
• M1 (D50): This mode is designed to simulate industry-standard daylight (D50), including a specific amount of UV light. It measures the color as it would appear in a professional viewing booth, with the OBAs fully activated.
• M0 (Legacy): This mode uses an older standard of illumination, often found in legacy devices.

By switching between these modes, a print professional can isolate the effect of the OBAs and understand exactly how their materials will behave. The device isn’t just seeing color; it’s performing forensic analysis.

The power of this accessible, objective data cannot be overstated. One user, in a dispute with their Homeowners Association, used the device to prove that the colors on neighboring houses did not, in fact, conform to the approved scheme, winning their case not with argument, but with verifiable, spectral data. It is the ultimate conversation-ender.

Bridging the Gap Between Worlds

The journey from Newton’s prism to a pocket-sized spectrophotometer is more than a story of technological progress. It is the story of a relentless quest to build a bridge between our inner, subjective world of perception and the outer, objective world of physics.

Technologies like the Nix Spectro L are the modern piers of that bridge. They are not here to tell us that our eyes are wrong, but to provide a common language. They translate the fleeting, personal experience of color into the universal, repeatable language of mathematics. This translation allows a designer in London to communicate a precise shade of green to a factory in Shenzhen, ensures that the skin tones in a photograph are reproduced faithfully in a magazine, and finally, lets you find the exact can of paint to touch up that scuff mark on your wall.

They remind us that science, at its best, is not a cold, abstract discipline. It is a profoundly human endeavor to understand our world, and ourselves, just a little bit better—one spectral curve at a time.