CRI was designed for tungsten in 1965. Television colour cameras kept demanding more, TLCI. Then IES rewrote the whole framework, TM-30 (Rf for fidelity, Rg for saturation). Three numbers, three jobs.
Four ideas to carry into the next specification conversation you have.
Useful as a floor (Ra > 80 minimum) but blind to deep reds (R9) and saturated colours. Outdated for any premium spec.
R9 measures saturated red. A fixture can score Ra = 95 with R9 = 30 (terrible red rendering). Always spec R9 ≥ 60 for retail and hospitality.
Rf = fidelity (how close to the reference). Rg = gamut (how saturated). Premium spec: Rf > 85, Rg between 95 and 105.
Television Lighting Consistency Index uses a camera response curve. Required for film/TV studios. Different number, different question.
Minimum thresholds for typical Saudi project types.
| Space | Minimum metric | Notes |
|---|---|---|
| Warehouse · industrial | Ra > 70 | Function only, no rendering |
| Office · classroom | Ra > 80, R9 > 0 | Standard professional |
| Retail · hospitality | Ra > 85, R9 > 50 | Skin tones matter |
| Premium retail · gallery | Rf > 85, Rg = 95–105 | Use TM-30, not CRI |
| Hospital wards | Ra > 90, R9 > 80 | Skin assessment / diagnosis |
| Operating theatre | Ra > 95, R9 > 90 | Tissue colour critical |
| Broadcast / film | TLCI > 85 | Camera fidelity, not eye |
| Museum · conservation | Ra > 95, R9 > 90, TM-30 Rf > 90 | Artwork preservation |
Five reasons the lighting industry never settled on one number.
CIE 13.3 (1965) defined Ra as the average error across 8 pastel samples (R1–R8) against an incandescent or daylight reference. LEDs render the 8 samples well but can fail saturated reds (R9), deep blues (R12), and skin tones (R13). A high Ra hides those failures.
Early LEDs scored Ra = 80 with R9 = -50 (yes, negative). Apples looked grey. The industry added R9 as a mandatory spec line. Today, premium LEDs hit Ra > 90, R9 > 80 with violet-pumped or red-phosphor chips.
IES TM-30-15 (revised 2018, 2020) uses 99 Colour Evaluation Samples across the full visible spectrum. Rf (fidelity) is the analogue of Ra. Rg (gamut) is new, it tells you if the source over-saturates colours (Rg > 100) or de-saturates them (Rg < 100).
Television Lighting Consistency Index (EBU Tech 3355) simulates a broadcast camera's spectral response. A TLCI score reflects how the light will look on-camera after auto white balance. Required by major broadcasters; irrelevant for spaces that aren't filmed.
Spec the number that fits the space. For a warehouse, Ra > 70 is fine. For an Apple Store, no CRI value alone passes, you spec Rf, Rg, R9, and skin-tone TM-30 RcsH1 in one line. The metric is a contract, not a marketing slogan.
Our retail, hospitality, and healthcare lines ship with full TM-30 reports on every fixture batch, not just CRI.
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