Lighting does more than just illuminate—it shapes how we perceive texture, colour, space, and atmosphere. In environments where visual accuracy is essential—from retail spaces and museums to healthcare and architectural interiors—Colour Rendering Index (CRI) is one of the most critical metrics to understand.
CRI stands for Colour Rendering Index, a scale developed by the International Commission on Illumination (CIE) to measure how accurately a light source renders colours compared to a reference source (typically daylight or an incandescent bulb).
It quantifies the ability of a light source to reveal the colours of various objects faithfully in comparison with an ideal or natural light source.
Technically, CRI measures the differences in chromaticity between test colours lit by the test source and the same colours under a reference light. The smaller the difference, the better the colour rendering, and the higher the CRI score.
CRI is expressed as a value between 0 and 100, where 100 represents perfect colour rendering (equivalent to daylight or a blackbody radiator at the same colour temperature).
|
CRI Value |
Quality Rating |
Colour Rendering Characteristics |
Applications |
|---|---|---|---|
|
90–100 |
Excellent |
Very accurate colour reproduction. Subtle tones and natural colours are visible. |
Art galleries, museums, film/photography, luxury retail, healthcare |
|
80–89 |
Good |
Generally good colour rendering for most applications. Minor distortions may be present but not noticeable in most settings. |
Offices, commercial interiors, retail, residential |
|
60–79 |
Fair |
Noticeable colour shifts. Muted tones and some hues appear inaccurate. |
Industrial, storage, back-of-house lighting |
|
40–59 |
Poor |
Distortion of colours. Reds and skin tones often appear dull or unnatural. |
Non-visual applications only |
|
Below 40 |
Very Poor |
Major distortion of colours. Unusable for any design-related environment. |
Emergency or utility-only lighting |
High CRI values are especially important when colour discrimination is vital—like matching paint, selecting textiles, inspecting products, or appreciating artworks.
The CRI measurement process involves comparing the appearance of eight standard colour samples (R1–R8) under a test light source with how those same samples appear under a reference light of the same correlated colour temperature (CCT). These samples include muted tones like pastel pink, blue, green, and yellow.
Additionally, extended CRI values (R9–R15) offer more information about saturated colours, including R9 (strong red), which is often excluded from basic CRI calculations but is critical for skin tones, food, and textiles. Many LED lights score well on R1–R8 but poorly on R9.
An ideal CRI score:
1. Colour Fidelity in Visual Spaces
In galleries, luxury retail, and branded environments, accurate colour representation is essential. Imagine an art piece under low-CRI light: reds might appear brownish, and blues may look gray—undermining the creator’s intent.
2. Human Perception and Mood
Studies show that lighting with poor CRI can impact comfort, alertness, and even emotional responses. For spaces like hotels, healthcare facilities, and wellness centers, high-CRI lighting promotes well-being and trust.
3. Brand Accuracy
In retail, especially fashion and cosmetics, the wrong lighting can distort brand colours or product appearance, leading to returns, dissatisfaction, or a poor brand impression.
4. Workplace Functionality
In offices or manufacturing environments where visual clarity is needed, better CRI lighting improves productivity and reduces eye strain.
The industry has recognized CRI’s limitations—especially its reliance on only 8 colour samples and lack of detailed spectral information.
TM-30-18, developed by the IES (Illuminating Engineering Society), offers a more accurate and holistic view by:
TM-30 is especially helpful in advanced architectural, museum, and scientific applications—but CRI remains the industry standard for simplicity.
Lighting is more than just a practical necessity—it defines how space is experienced. CRI is a powerful tool to ensure that materials, artwork, skin tones, and branding appear as they should.
If you’re specifying lighting for:
…then demanding a CRI of 90 or higher isn’t a luxury—it’s a standard of quality.
OneFrame is a New Zealand based speciality manufacturer delivering sustainable solutions both locally and across international waters. Our team has a dedicated focus on influencing and educating architects, specifiers, designers and those that share our passion for a more sustainable tomorrow through innovative delivery.
We are constantly being challenged by our clients and driven to transform their bold ideas into amazing realities. Innovation is our passion, it's part of our DNA and we are constantly striving to positively influence the industry by what we deliver to market.
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