CRI, R9 and TLCI: Understanding LED Color Quality
CRI is the most quoted — and most misunderstood — LED color metric. For professional lighting, CRI alone is not enough: R9 and TLCI tell you what CRI hides. This guide explains all three and how to use them when sourcing COB LED modules.
CRI (Color Rendering Index): The Baseline
CRI (Ra) is the average fidelity of a light source in rendering the first eight pastel test colors (TCS01–TCS08) versus a reference illuminant of the same CCT. Scale 0–100.
- What it's good for: rough comparisons of overall fidelity in general lighting
- What it misses: saturated colors — notably red. A CRI 90 source with terrible red rendering still scores CRI 90.
R9: The Red Metric CRI Hides
R9 measures fidelity for the ninth test color: saturated red. It is excluded from Ra — and it is precisely the wavelength region where phosphor-converted LEDs are weakest.
| R9 value | Visible result |
|---|---|
| < 20 | Skin looks gray/flat, reds turn brown — common in cheap high-CRI claims |
| 40–70 | Acceptable for architectural; marginal for camera |
| > 90 | Professional film/broadcast grade; skin and fabric render naturally |
Always ask for R9 in writing. TYANSHINE tunable white COB platforms specify R9 alongside CRI (up to CRI 98) for camera-critical configurations.
TLCI: What the Camera Sees
TLCI (Television Lighting Consistency Index) was developed by the EBU for broadcast. Instead of human observers, it models a standardized television camera and reports the correction a colorist would need.
| Metric | Observer | Use case |
|---|---|---|
| CRI / Ra | Human eye, pastel colors | General and architectural lighting |
| R9 | Human eye, saturated red | Skin-tone quality check |
| TLCI | Standardized TV camera | Broadcast and film fixtures |
| TM-30 (Rf/Rg) | Modern color science, 99 colors | Fuller fidelity (Rf) + gamut (Rg) picture |
A fixture can be CRI 95 and still TLCI 70 — meaning visible grading effort in post. High-end film fixtures target TLCI ≥ 85–90.
TM-30: The Modern Complement
IES TM-30 reports Rf (fidelity, like an improved CRI over 99 color samples) and Rg (gamut area: >100 means saturation is increased, <100 muted). Rf/Rg together describe both accuracy and character of the light — useful for cinematic “look” decisions, not just fidelity.
Practical Sourcing Rules
- Never accept “CRI 90+” alone — request CRI, R9 and (for camera fixtures) TLCI at your operating CCT and Tc
- Check the whole CCT range for tunable white — R9 at 2700K says nothing about 6500K
- For color fixtures, fidelity metrics apply to the mixed white, not the saturated primaries — ask for gamut data (see RGB vs RGBW vs RGBLAC)
- Beware CCT-shifted claims — CRI must be measured against the reference at the same CCT
TYANSHINE provides CRI, R9, TLCI and TM-30 data for its professional COB platforms. Explore high-CRI tunable white COB or read how MacAdam binning keeps these numbers consistent unit-to-unit.