Mystery Chicken: Revealing the Color Rendering Index!

by | Jan 28, 2024 | blogs, Lighting Metrics | 0 comments

Introduction

Picture this: you’re at the grocery store, eyeing the chicken fillets on the shelf. The meat looks fresh and pink, but when you place it in your cart, something strange happens—the color transforms into a more yellowish, bland hue. Intrigued, I decided to investigate with the Color Rendering Index.

I knew that the display shelf lighting could be playing tricks on my perception. Armed with a handheld spectrometer, I returned to the store to measure each light’s Color Rendering Index (CRI) and unravel the mystery behind the chicken fillet color shift. The results? Surprising and a bit shocking.

Quantum PAR Meter

Fig 1 Chicken Filets under shelve lighting

Quantum PAR Meter

Fig 2 Same filets under general floor lighting

Understanding Color Rendering Index (CRI):

CRI is a metric to gauge a light’s ability to render colors on objects accurately. Lighting designers must create captivating displays, ensuring that products’ colors shine true. Museums leverage high CRI lighting for paintings’ visual color fidelity. But how do we use CRI to compare the chicken colors – which is the real color; fleshy pink or bland yellow?

CRI is measured against natural sunlight, the gold standard, on a scale from 0 to 100. A CRI rating of 90+ indicates that the light can reproduce colors as well as sunlight. Sunlight’s significance lies in its balanced spectrum, encompassing all colors at sufficient intensities.

Shedding Light on the Results:

The CRI measurements from my handheld spectrometer revealed unexpected findings:

  • General Floor Lighting (yellow bland chicken color): CRI = 87.8
  • Shelf Lighting (fleshy pink chicken color): CRI = 82.5
Indoor Horticulture

Fig 3 Museum Lighting

Fig 4 Left is CRI for bright pink filets, Right is for bland filets.

Hold on—why does the general floor lighting, rendering our chicken fillet bland and yellow, receive a better rating? To answer this, we delve into different flavors of CRIs.

Exploring a different Color Rendering Index:  TM-30-18

While longstanding, the traditional CIE CRI (above) faces challenges and cannot reveal some aspects of lighting.

Enter TM-30-18, a more recent and advanced CRI. It can diagnose why our chicken fillets appear fleshy pink under shelf light, and yet score a subpar CRI rating.  The TM-30-18 graphic in Fig 6 (left image) reveals a bulge in the red-purple (red line) indicating oversaturation beyond natural sunlight (black line) – thus affecting overall CRI rating.  Even the numeric metric can exceed 100, indicating over-saturation beyond sunlight, providing insights that the traditional CIE CRI cannot.

Oversaturated Colors

Fig 5 Oversaturation of colors can be uncomfortable

Fig 6 Left is CRI for pink-fleshy chicket with bulge in red-purple, Right is for bland filets and notice it is closer to sunlight.

In short, our chicken fillets appear more beautiful under shelf lighting because the colors are artificially induced. However, the bland yellow color under general lighting is closer to what the colors would be under sunlight.

Enhancing colors to your advantage? – for better or for worse, we call it Marketing :).

Learn more about TM-30-15 (TM-30-18) [here].

Other CRIs, like CQS and Cinematic/Photographic CRIs (TLCI, SSI, TLMF), offer additional advantages in different applications.

Figure 7  Photons of Light

Why the Color Rendering Index matters:

Consumers often take light for granted when shopping. Little do they realize the meticulous fine-tuning of lighting by store designers and curators, using CRI to showcase the full spectrum of colors, enticing us to buy that perfectly illuminated chicken fillet. 😊

Curious to learn more about CRIs? Dive into the fascinating world of lighting and color rendering [here].

UPRtek Handheld Spectrometers with CRI [here]

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Figure 8 Photo by Andrew Leu on Unsplash

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Replete with major CRI indices (CIE CRI, TM-30-18, CQS, TLCI)

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UPRtek (est. 2010) is a manufacturer of portable, high-precision light measurement instruments; Handheld Spectrometers, PAR meters, Spectroradiometers, Light Calibration Solutions.

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