Wesley Chapel, Florida Hospital, Florida. Image courtesy of www.Planar.com.
Keeping up with high-tech evolution is like surfing. There's lots of waiting for the right moment, but you need to keep a sharp eye and be ready to pivot quickly to catch the wave of change. Otherwise, you could be left dead in the water while others surge forward with new technology. To help you seize the momentum, CPM spoke to editorial consultants and manufacturers including Absen, Elation Professional, Daktronics, and Digital Projection to provide technical insight and expert advice for this article.
Projectors or LED walls?
You should be looking at both technologies for large-scale displays. They are both evolving, and they are very different. Here are some key distinguishing factors. Projectors bounce light off a white or silver screen, or occasionally throw it from the rear. Video displays like flat panels and LED walls emit light directly.
For displays, what matters is intensity and size. For projectors, intensity, size and volume of the illuminated cone all matter. Some LED wall manufacturers publish specs in lumens, the unit used for projectors. But the perceived brightness may be very different, since it's impossible to project black off a white screen, while LED displays can actually display black.
Higher contrast can make LED images appear “brighter” and “sharper,” especially in ambient light. Most LEDs will be run well below 50% maximum brightness indoors, especially if theatrical lighting and IMAG cameras are part of the production.
Projector resolution is designed in and has increased from XGA (1024 x 768 pixels) to WXGA (1280 x 800 pixels), HD (1920 x 1080 pixels) and now 4K (4096 x 2160 pixels). An HD projector can display a WXGA signal via upscaling, but a 4K signal would have to be scaled down.
Your church should be looking at both projection and LED video wall technologies for large-scale displays.
LED displays have a fixed distance between one LED and the next, called pixel pitch. Smaller pitch equals higher resolution. Allow about 3.5 feet (a meter) of viewing distance per millimeter of pixel pitch to avoid pixelization. Scaling should be built in: “Wall controllers like ours will scale the input image up or down to match the actual resolution of the videowall,” says Matt Anderson of Alpharetta, Ga.'s Daktronics Inc.
Projectors: New light sources, new inputs
The lamp is the most expensive part of a projector. Today, you have choices like high-intensity discharge (HID) lamps that use less power and generate less heat than Xenon or UHP, while producing more lumens. Laser lamps like those in Kennesaw, Ga.-based Digital Projection's Insight 4K Laser projectors and others from Sony and Panasonic are also more efficient: DPI Product Manager Phil Laney says that if these projectors are left on overnight in an air-conditioned space, they'll be blowing cool air, not hot, by morning. Laser lamps have a 20,000-hour useful lifespan and a wide color space with particularly rich reds and blues. WUXGA models output 1920 x 1200 (or 1080p) images, enabling them to handle almost all of the content currently available. If you want to be ready for 4K, DPI already has 4096 x 2160 projectors for you. Lasers are great for environmental projection because of their brightness and depth of field—third party software can tailor the image to surface contours.
LED lamps are also very efficient, and will last up to 50,000 hours. As a projector light source, LED images look brighter because of higher contrast and wider color space. But their lower lumen output works better in light-controlled environments, for rear projection, or with smaller screens. For brighter rooms and larger screens, laser light sources are a better choice.
Check for warp and blend controls along with precise geometry controls. These will let you expand coverage with overlapping images or overlay multiple projectors for added brightness.
LED Video Walls: A whole new display option
LED displays have been getting bigger, brighter, sharper, and less expensive at the same time. “Prices are dropping, but video walls still have a higher initial purchase price than projectors,” admits Ewa Tsai, sales manager (house of worship) for Absen in Orlando, Fla. “Over an 8-to-10-year product lifespan, churches can save thousands or even tens of thousands in maintenance and operating costs,” she adds. Every facility is unique, however, so your own payback period and expected lifespan can vary.
LED video walls can have different dimensions and need not be rectangular. Because the pixel pitch is fixed, the bigger the wall, the higher the maximum resolution. Portable displays can be reconfigured at any time: some include software that makes routing signal and power a lot easier. When it comes to input formats, video walls can go head to head with projectors: controllers will typically accept all the analog or digital signals you can throw at them.
LED displays all look different. Ideally, your entire wall will be built with panels whose LEDs came out of the same bin: that way the color spectrum will be consistent across the wall. Buying the entire wall at the same time is the best way to get bin-matched LEDs. Calibration and careful construction that minimizes differences between adjacent panels are also important. Red Walter, product specialist with Elation Professional in Los Angeles points out that “tolerances are plus/minus, so a panel with a 3% tolerance can actually vary 6%.” The tighter the tolerance, the more pricey the panel.
As with any type of video display, constant use of a solid color will decrease its life exponentially more than color-balanced video. Drift is directly related to how much of that particular color is used during the production. Even so, you're more likely to lose the electronics first. “Color drift is normally perceived as a change in the white temperature,” Walter explains. “If you have the Coke logo burning for a year on one panel and you then put on a full white, the area where the red had been will be noticeably more aqua or cyan. That's because the red LEDs will be degraded while the green and blue LEDs will still be very strong [since] they haven't been used as much. Or white LEDs can dim over time as the components and gases break down—that has a similar visual effect.” You can re-calibrate the wall, but shifting the white balance will shrink the color space.
How wide your color space is will depend on both the LEDs and the controller. “All the Elation processors have a minimum of 14-bit processing, and some are 16-bit,” Walter adds. “The controller can prioritize either brightness or grey scale accuracy.” But be careful: If you go as wide as possible, you may push the LEDs to their limits. The old familiar NTSC standards give a “warm” look, but may prevent you from displaying intense colors such as deep ruby reds or forest greens. Ask if dimming and color balance are separate functions within the videowall signal processing chain: “Daktronics separates dimming from color balance to ensure clear, sharp images,” Alexander reports.
Preventative maintenance and the standard lifetime of the technology will keep an LED wall functioning much longer than a projector. Walter says, “Fans, power supplies, the video receiver card, or the CAT5 data cable are the normal maintenance issues; you can expect these components to deliver three to five years of normal usage.” Ask about service plans and tech support, and redundancy, especially in the control system.
There's no lack of choices to consider in 2015. The upside is that any of these technology waves will give you a smooth ride to bright, crisp, beautiful images.
