By Joe Casper, Chief Technology Officer, Eaton’s Ephesus Lighting Business
Sports broadcasting has come a long way since its early days. Super Bowl I—then called the AFL-NFL Championship Game—aired in 1967. Compare the way that at-home broadcast looked to what the LED sports lighting technology for the 2015 Super Bowl XLIX at the University of Phoenix stadium delivered, and the difference is like night and day.
Many things are different. Today’s LED sports lighting technology—from the components of the luminaire, including the composition of the LED itself, to the power supply, lensing, circuitry, software, and controls—can now function as a complete system. The result is sports lighting not only pleasing to the human eye but also optimized for the increasingly sophisticated broadcast cameras that capture the game and deliver it to televisions at home. Essentially, this is digital lighting designed for digital broadcast technologies, beyond high definition (HD) to the emerging technologies of 4K ultra-high definition (UHD) and 8K UHD, collectively called super hi-vision.
The 2014 World Cup was a test for 4K UHD broadcast. The 2016 Olympics will present another test for 4K UHD and 8K UHD broadcast. For the Tokyo 2020 Olympics, Japanese broadcaster NHK intends to broadcast as much of the games as possible in 8K UHD. The cost of 4K UHD televisions is decreasing, making them attainable for fans desiring the best at-home viewing experience. Today’s LED lighting innovations are capable of delivering lighting optimized for these broadcast technologies and will enable the best viewing experience on advanced televisions.
Light Quantity and Quality
Ultra-high-definition cameras require aperture settings that will let in the ideal amount of light. As broadcast resolution increases, so does this required aperture setting. When the ideal amount of light is achieved, the lighting reaches the camera’s digital sensors, optimizing the field depth and minimizing adjustments required from camera operators.
While light quantity is very important for broadcast, light quality is perhaps more so. One critical aspect of light is how well it enables the accurate depiction of colors for broadcast. The Television Lighting Consistency Index (TLCI) is becoming the preferred measurement for color lighting accuracy in digital broadcast. TLCI considers a greater spectrum of light, including that which is captured by digital broadcast cameras, rather than only the light spectrum perceived by the human eye, as in the more traditional color rendering index (CRI).
While both are measured on a scale of zero to 100, TLCI and CRI don’t directly correlate, so comparing their values to promote understanding of TLCI requires some explanation. For example, 65 TLCI is currently considered very good, while 65 CRI is unacceptable for today’s broadcasts. In fact, many sports broadcasts require 90 CRI, while 90 TLCI lighting reproduces color so accurately that a broadcast colorist would likely not alter anything to improve color quality for the viewer at home.
Some sports lighting products today achieve a TLCI of at least 65 by using a propriety diode incorporating a very precise blend of phosphors to generate a spectrum of light that is uniquely optimized for perception by 4K UHD and 8K UHD broadcast cameras. Select luminaires have even achieved a 90 TLCI rating, though this technology is not yet feasible for widespread adoption in sports venues. With innovations currently in development, the widespread availability and affordability of fixtures with higher TLCI ratings will keep pace with anticipated adoption of 4K UHD and 8K UHD broadcasts and their increasing requirements.
Flicker has been a concern of metal halide systems and some lesser LED systems, but some LED fixtures employ pulse width modulation, a familiar concept in solid state lighting, to enable flicker-free slow-motion capture in sports broadcasting. Some companies are taking this concept further, using a unique, super high-speed phase-shifting technology to enable optimal lighting performance compatible with super slow-motion capture. This technology will support frame rates in excess of 8000 frames per second, with no potential flicker with even the most sophisticated cameras, thereby ensuring compatibility with new broadcast technologies.
Color-Temperature and TLCI Tuning
Another technology is color-temperature tuning and TLCI tuning. Standards for professional sports are developing that specify “warmer” tones for basketball and “cooler” tones for hockey. In court sports, flesh tones appear truer and the overall color tone more favorable under a warmer color temperature (similar to that of candlelight). Cooler color temperatures are preferred for hockey, since they cause the ice to look more vivid and the puck to be more easily seen. This color-temperature tuning capability was recently deployed at Bridgestone Arena, home of the NHL’s Nashville Predators and host of the 2016 NHL All-Star Game.
TLCI tuning allows for the adjustment of the spectrum of light generated by luminaires to compensate for environmental differences in venues. For example, a football game beginning under a bright afternoon sun will have different lighting characteristics and spectrums as the game progresses and the sun sets. Today, the spectrum of light produced by lighting fixtures can be altered to compensate for such shifts, providing a more uniform appearance throughout the broadcast and simplifying the broadcasters’ job.
More technologies beyond 4K UHD and 8K UHD will surely be on the horizon. While it may not yet be certain what these technologies require from lighting, our industry will continue to be on the leading edge of delivering what’s possible.
This article was originally published in the February 2016 issue of ei, the magazine of the electroindustry.