Introduction to Critical Color Evaluation Light Booth Technology
Light comes in many different flavors – daylight, tungsten (incandescent/halogen), fluorescent, LED, fire, and others. Products look very differently under these types of lights. Because of brand recognition, product desirability, and regulatory compliance, critical color evaluation has been an ongoing challenge for decades. Critical color evaluation is the process of assessing how colors appear under different lighting conditions to ensure accuracy, consistency, and suitability for a given purpose. It’s “critical” because the exact appearance of color can determine quality, perception, and industries like printing for brand colors, textiles, cosmetics, plastics, automotive, paint, lighting, photographic sensors, and display manufacturers are dependent on critical color assessment. Testing adherence to visual assessment requirements and standards is another important aspect of color evaluation.
Color evaluation has now has become more complex and dynamic than before because with the introduction of LED lighting, halogen and fluorescent lamps are being banned or replaced worldwide. Most commercial and domestic lighting is converting to LEDs due to their efficiency, compactness and flexibility. This shift to LED lighting, which itself comes in various flavors/spectrums is having a major impact.
To address this situation of color variability, lighting standards have been created by the CIE, such as A, D50, and D65 among others. Visual assessment tools such as light viewing booths with standardized lighting enable critical color management for textiles, print, paint and many other products. Light booths can help identify a phenomenon called metamerism, where two samples have the same appearance under one lighting condition, but appear different under another. It is the spectral quality of the light that affects how humans or sensors see color and all light sources have different light spectrums.
In the past, industries have standardized on a compromise and used one or more lighting conditions to best test how their products will be viewed. Today, with LED technology the lighting options are almost limitless and lighting will vary from store to store. Ideally, product managers should evaluate appearance using a light booth with every light source under which the final object will be seen, in addition to standard illuminants, to ensure the color appearance continues to meet expectations.
Telelumen LED Light Booth Benefits
Telelumen sells light booths using their programmable full spectrum LED luminaires in cooperation with GTI Graphic Technology, a world class leading vendor of light booths. Light booths based on the Telelumen programmable spectrum LED light sources deliver the solution you need and bring your critical color evaluation solution in to the 21st century.
All LED based light booths provide fundamental benefits that result in superior performance:
- No lamps to replace saving cost and the environment
- No need for multiple light booths with different light sources
- LEDs remain accurate longer and live longer than legacy vacuum lighting technology
- Accuracy and repeatability between systems is much higher than old lamp technology, creating a more accurate and efficient global supply chain.
The Telelumen Advantage
- All Telelumen light booth products provide high fidelity color rendering, lighting standards replication, wide dynamic range, and user friendliness
- Telelumen uses 8 or 24 LED channel luminaires to create high fidelity light spectra
- Telelumen light booths can reproduce all standard CIE lighting standards in one booth – A, D50, D65, TL 84 fluorescent chromaticity equivalent and others. This creates multiple illuminants in one box with no need to swap lamps.
- For ease of use and simple operation, all booths have a pre-programmed panel for preset lighting conditions
- Customization – custom spectra can be defined at time of manufacture, or via optional software any time to replicate a customer’s lighting system such as a brand or store lighting.
- Factory Calibrated
- Product options exist for two luminaire booths that allow direct side by side comparisons under different lighting conditions (shown at right)
- With optional software:
- the booths can be programmed to view one color at a time for detailed examination of camera/photo sensors response
- Visually compelling continuous sequences of light spectra can be “played” in real time to demonstrate how objects change when certain parameters are varied such as a CCT “sweep”.
- Advanced applications are possible through easy to use GUI software - illumination intensity, color temperature, chromaticity and other parameters can be programmed to vary over time
Telelumen can also retrofit and upgrade older legacy vacuum technology light booths from Xrite, GTI, Veriwide and others.
For critical visual evaluations of your product, you need tools that can cover the lighting situations you will face in the real world as well as the CIE “standards”. Telelumen delivers such a solution.
Critical color evaluation is a complex process with the need to develop new standards for new technologies. Telelumen is actively participating in human perception studies (IMLEX) and standard setting organizations such as AATCC.
Telelumen Light Booth Products Based on Octa and Dittosizer LED Luminaires
Telelumen sells small, medium, and large sized light booths which can incorporate single or dual luminaires. The luminaires are the Telelumen Octa (8 LED color channels) and Dittosizer (24 LED color channels). The medium sized light booth (25"x40"x25" viewing area) is based on the GTI CMB-2540 model and typically has one Octa luminaire. The large light booth (30”x 52”x 30” viewing area) is based on GTI model CMB-3052 model and comes with two luminaires.
Each booth comes standard with at least six factory set built in illuminants. There is also optional software that can be used to customize the spectral power distribution (SPD) and change/upgrade the built-in illuminants under custom computer control. The medium sized CMB- 2540 model has 6 buttons corresponding to 6 spectra. In all booths, the critical CIE standard illuminants can be reproduced as well as any commercial LED lighting spectra used in the industry. For ease of use, the CMB-3052 based model has a touch panel that has 12 standard or custom spectra installed. These touch panel spectra can be changed any time via optional software. Under computer control the booths are capable of continuously playing any sequence of custom spectra (such as a CCT “sweep”) in a linear fashion or a continuous loop and one color at a time (see Photo Booth application below).
The Octa luminaire based light booths are high performance instruments at an economical price. Based on the 8 channel/LED color programmable luminaire they provide very even lighting with 1000:1 dimming, and illumination from 1-1500 lux depending on the SPD, using a one luminaire option. They have the capability to produce all the necessary CIE standards such as D65 and A, for example. The available 8 color channels and frequencies which include UVA, are shown above on the left.
The Dittosizer based light booths enjoy the highest performance possible based on a 24 channel/LED color programmable luminaire. The available colors and frequencies are shown on the left. With a hyperspectral range that includes UV, UVA, visible and NIR, phenomena such as fluorescence in materials can be viewed and examined.
The large light booth (GTI CMB-3052) is available with two Dittosizer luminaires installed. A two luminaire version makes side by side comparisons under different lighting conditions possible. This is a unique and unmatched capability in the critical color evaluation market.
With 24 channels and output capability to produce illumination up to 4500 lux with > 1000:1 dimming (depending on the SPD), the possibilities are limitless.
For more details, please refer to the Octa based Light Booth Data Sheet or the Dittosizer based Light Booth Data Sheet. All light booths are calibrated at the factory. For questions on retrofitting or customization, please use our Contact page.
Application – Photo Booth Camera Testing at York University
One of the more important applications for critical color evaluation is the response of camera sensors. Pictures taken in the real world are taken under all possible lighting conditions. The sensor response and any accompanying digital processing need to be tested in laboratory conditions before releasing a product into the real world.
One example of such testing is Professor Michael S. Brown (Canada Research Chair in Computer Vision, Dept. of Electrical Engineering and Computer Science) who has set up a laboratory at York University, Toronto Canada using a Telelumen Light Viewing Booth for testing in-camera processing. As shown to the left, the test set up uses the Telelumen Light Viewing Booth for easily and quickly simulating custom multispectral lighting to capture the same scene with an RGB camera over 7 different illuminations, as well as the D65 standard illuminant. The lab uses this data for a variety of spectral measurement and estimation tasks.
Professor Brown’s experience with Telelumen and its products has been a successful one - “Telelumen's Octa Light Player, a programmable spectrum LED luminaire, and its software are crucial in my research targeting in-camera processing. The ease of programming the light spectrum is essential to my testing of camera sensors under different conditions. Over the years, I have purchased multiple Light Viewing Booths of different sizes with the Octa Light Player installed. The Telelumen team has been highly responsive, providing outstanding support whenever we needed assistance. Telelumen's commitment to technical quality and customer service makes them a reliable and essential partner in our research efforts.”
