Color Rendering Demo: CRI vs TM-30
Two lights can share the same CRI and still make the same fabric, wood and skin look different. Switch between the example sources below to see why.
Same CRI, different materials
What the numbers say
| Example source | CRI (Ra) | TM-30 Rf | TM-30 Rg | Red chroma |
|---|
Rf is fidelity, meaning how close colors look to the reference. Rg is gamut, where above 100 means more saturated overall and below 100 means duller. Red chroma (Rcs,h1) shows whether reds get richer or flatter, and that's the one CRI hides most often. All values here are example data.
How to spec it (TM-30 Annex E)
Annex E gives three design intents, each with priority levels 1 to 3, where 1 is the strictest. Preference (P) is for natural, pleasing spaces like residential and hospitality. Vividness (V) is for punchy display. Fidelity (F) is for color matching. A product can be rated with a code for all three, such as P1 V3 F-.
| Spec | Criteria |
|---|---|
| P3 | Rf ≥ 70, Rg ≥ 89, red chroma between −12% and +23% |
| F3 | Rf ≥ 85 and red fidelity Rf,h1 ≥ 85 |
| P3 + F3 combined | Rf ≥ 85, Rg ≥ 89, red chroma −12% to +23%, Rf,h1 ≥ 85 |
The full nine-cell matrix is in the DOE tutorial linked below. The criteria assume 200 to 700 lux in a space with a variety of colors.
The real fabric demo
- Pick two lamps with the same CCT and similar CRI.For example, two 3000K, 90 CRI lamps where one is high fidelity and one has red chroma well below zero. Ask the manufacturers for TM-30 reports to choose them.
- Build two identical boxes or bays.Use matte white or neutral gray inside, the same fixture type and beam, and set both to the same light level.
- Use the client's real materials.Include a red or coral fabric, a skin-tone swatch or a hand, walnut and white oak, a navy, a green and a marble or stone. Add a ColorChecker card for a neutral reference.
- Show them blind, then reveal.Let the designer choose which bay looks right before showing the spec sheets. Both say CRI 90.
- Show the TM-30 graphics.Point to the red chroma and fidelity numbers that explain what they just saw, and connect it to an Annex E code they can put in a spec.
What to ask manufacturers for
- A full TM-30 report with Rf, Rg, the color vector graphic and the 16 hue-bin values, not just CRI.
- Red chroma (Rcs,h1) and red fidelity (Rf,h1), or the Annex E code it meets (for example P1 V3 F-).
- Color consistency between units (MacAdam steps) and how far it sits above or below the black-body curve (Duv).
- Color shift over life and at the dimmed levels you'll actually use.
- A physical sample, so you can check it next to the real materials.