The CRI Scale
CRI is measured on a scale of 0 to 100. 100 = perfect colour rendering (identical to natural sunlight). 80–90 = good colour rendering - all colours appear natural and distinguishable. 70–80 = adequate colour rendering - slight colour distortion in some hues. 60–70 = poor - noticeable colour distortion, common in budget LEDs. Below 60 = very poor - old sodium lights (CRI ~25), fluorescent tubes (~60–70). For road lighting in India, BIS and PWD typically specify minimum CRI 70. For retail, healthcare, and precision work: CRI 80+ minimum. For art galleries, medical inspection: CRI 90+.
Why CRI Matters for Road Safety
Under low-CRI sodium lights (CRI ~25): all vehicles and road markings appear in yellow tones - a red car looks dark brown, a blue sign looks grey. This makes it harder to quickly identify vehicles, pedestrians, and hazards. Under high-CRI LED lights (CRI 70+): vehicle colours are distinguishable, road markings are clear, and the human visual system's contrast detection works as intended. Emergency service responders find it significantly easier to work under high-CRI lighting - identifying blood, fire, and hazard markings accurately.
CRI for Different Environments
Road and street: CRI ≥70 minimum, 70–80 recommended for main roads. Industrial factory: CRI ≥70 for assembly, CRI ≥80 for QC and inspection. Retail shop interior: CRI ≥80 (food retail CRI ≥90 makes produce look fresh). Hotel and restaurant: CRI ≥90 for premium ambience. Residential: CRI ≥80 preferred for comfortable home lighting. Sports ground: CRI ≥80 for broadcast cameras. Medical facility: CRI ≥90 for accurate patient skin tone assessment. All Xera Tech outdoor LED products are CRI ≥70, with higher CRI options available.
