A new measure shows how many spectral mixes make the same white light

One White, Many Spectra

Here’s the dilemma: A basic white LED—like the steady 3000K lamp above your kitchen island—has a single, fixed spectrum. Its color rendering can be measured once with CRI or TM-30. End of story.

But modern tunable lights, packed with three, four, sometimes even seven or more varieties of  LEDs—red, green, blue, amber, lime—can hit the same shade of white in dozens or even millions of different ways. These spectral tricks, called metamers, fool the eye but change everything about how colors look on objects.

A museum curator tweaking a spotlight might use this flexibility to make a painting’s reds richer without changing the gallery’s ambient white. A retailer might tune fixtures so drab winter coats look vivid under the same CCT that made colorful swimsuits pop in summer. A hospital might tune spectrum for circadian comfort, all while keeping the white steady to the patient’s eye.

Until now, designers had no good way to quantify just how much wiggle room a tunable fixture really had. CRV aims to fill that void.

So What Exactly Is CRV?

In simple terms, CRV measures how many distinct ways a tunable, multi-primary LED system can render colors—without shifting away from a target white point. As Royer’s team puts it: “CRV quantifies the extent to which a multi-primary product can vary color rendition within a defined set of parameters.”

In practice, that means taking all the possible spectral mixes that can produce a single chromaticity—same white, in other words—and counting how many unique combinations give meaningfully different color rendition scores for fidelity, gamut, and hue boost.

The result is a percentage: higher CRV means more flexibility to fine-tune how colors appear, lower CRV means you’re basically stuck with one look.

Why CRV Isn’t a New CRI

Royer and his co-authors are clear: CRV doesn’t compete with CRI or TM-30. It complements them. Those older tools still score how good colors look for a single spectrum. CRV scores how much range you have to adjust that look, all while holding the white steady.

Think of it this way: CRI is a snapshot. CRV is the field of possible variations around that snapshot. And for tunable, multi-primary systems, that field can be wide—or surprisingly narrow.