What is CRI on an LED strip test report, and how do I read Rf, Rg and duv?
CRI in LED lights is the average score of eight pastel test colours against a reference source, so it says nothing about deep red on its own — that is R9, and a board can average Ra 90 with an R9 of 20. TM-30 replaces the average with 99 samples and reports Rf for fidelity and Rg for gamut; DENO full spectrum tape typically measures Rf 93 with Rg near 100. Finally check duv, which shows whether the white sits green or pink of the blackbody locus; DENO holds it inside +/-0.003.
Rf, Rg and the vector graphic
Rf replaces Ra with 99 colour evaluation samples spanning real materials rather than eight pastels, so it is much harder to game. Rg reports whether the source expands or compresses saturation: below 95 colours look washed out, above 105 they look artificially vivid, which some suppliers market as 'vibrant'. The vector graphic is the honest picture — it shows exactly which hue bins are distorted and by how much.
Alongside TM-30, each DENO lot ships an SPD file at 5 nm resolution. Plotting it reveals what no index can: the height of the pump spike, the depth of the 480–500 nm cyan region, and the length of the deep-red tail past 650 nm.
Claims worth checking
Three patterns come up repeatedly in datasheets. A high Ra with no R9 figure usually hides a weak red tail. A CRI value quoted without a CCT is meaningless, because rendering changes across the range. And an efficacy figure quoted at 50% drive current will not be reproduced in the installation.
Ask for the measured report on the actual production lot rather than a reference sample. DENO supplies it by default, including per-reel binning data where 1-SDCM consistency has been specified.
Industry references and standards
- Museums & conservation — CIE 157: Control of Damage to Museum Objects by Optical Radiation — Exposure limits and damage factors used by museum lighting schedules.
- Museums & conservation — Canadian Conservation Institute — Light, Ultraviolet and Infrared — Conservation guidance on lux hours and UV load for sensitive collections.
- Museums & conservation — Getty Conservation Institute — Research on display lighting and colour rendering in gallery environments.
More full spectrum answers
- What is the difference between a high CRI LED strip and a full spectrum LED strip?
- Is violet-excited high CRI LED lighting better than a normal blue-chip white LED?
- Is 90 CRI enough, or do you need a 95 or 98 CRI LED strip?
- Which high density LED strip stops you seeing dots in a shallow cove?
- Are high CRI LED strips available in 24V, and do they dim without changing colour?
- Can you use a full spectrum LED strip to grow plants?