Access the most comprehensive pro-AV resource in the industry to explore audiovisual equipment catalogs, compare prices, locate service providers and review case studies.
Go to AV-iQ
Projected Image Standard: What’s in it For You?
Type: Article, Report or Whitepaper
Date: July 2011
InfoComm International® recently released its newest performance standard, ANSI/INFOCOMM 3M-2011 Projected Image System Contrast Ratio [PDF overview]. The voluntary standard seeks to define acceptable minimum contrast ratios for projected images, relative to their application, for both installed systems and live events.
That’s right, live events.
Many live event and rental and staging professionals may not spend a lot of time thinking about contrast ratios. Whether they’re setting up a projection system in a hotel ballroom or an auditorium, they often assume that if they throw more brightness at a screen, it will mitigate issues caused by ambient light and other venue characteristics. After all, in live events and rental and staging, it can be hard to control ambient light, whether from ill-placed windows, exit signs, the glow of an audience’s laptop screens, or just gaps under doors.
Still, depending on the event, contrast ratio can be important to achieving client satisfaction, even if, in the end, the client is unsure why a projected image looks as good as it does.
“In the live events world, there probably needs to be more awareness of contrast ratio,” says Janne Mummert, CTS, of Video Equipment Rentals in Glendale, CA, and chair of InfoComm’s Rental and Staging Council. “But there’s always been an assumption — and not necessarily a wrong one — that as you move up in brightness you’re getting a better contrast ratio.”
While the quality of a projected image is not determined by contrast alone, an audience’s ability to retain projected information, such as spreadsheets or maps, or enjoy projected video, such as movies or live IMAG (image magnification) presentations, is greatly enhanced when the content is projected at an appropriate minimum contrast ratio. Now, using a light meter, checkerboard pattern and calculations spelled out in the new ANSI/INFOCOMM standard, live events professionals can ensure their clients see projected content at the optimal contrast ratios.
Inside the Standard
It’s important to understand the difference between contrast ratio as defined by the Projected Image System Contrast Ratio standard and contrast ratio as spelled out in the feature sets of high-brightness, high-end projectors that many live events professionals deploy. Contrast ratio as defined in the standard is a “system” contrast ratio, taking into account not only the projector, but also the projection screen and the impact of ambient light. Unlike prior ANSI standards for contrast (ANSI/NAPM IT7.228-1997 Electronic Projection — Fixed Resolution Projectors and ANSI/PIMA IT7.227-1998 Electronic Projection — Variable Resolution Projectors, both retired as standards in 2003), which measured direct light from a projector, the new ANSI/INFOCOMM standard measures luminance reflected from or transmitted through the projection screen.
The standard defines four minimum contrast ratios depending on the type of information projected and the room’s environmental characteristics, specifically its lighting. For example, if an audience isn’t necessarily meant to engage with the content — maybe it’s designed as a projected backdrop in a convention lobby—the standard’s minimum contrast ratio is 7:1. For everything from PowerPoint® presentations to full-motion video, the minimum contrast ratios range from 15:1 to 80:1.
The challenge in live events is that content can vary dramatically. Understanding in advance as much as possible about what the client expects to project is important to achieving the right contrast ratio.
“In live events, your content changes throughout the course of the event,” says Tom Stimson, CTS, chairman of the InfoComm Leadership Development Committee and a long-time veteran of the live events industry. “And while 90 percent of the event is going to be PowerPoint, at some point you may switch to a video the client produced and spent hundreds of thousands of dollars on.”
The fact is, in live events, the demands of projected images can actually be much higher than in installed systems. A spreadsheet may not be a challenge, although the proper contrast ratio certainly makes it more legible. But when it comes to projecting detailed schematics, 3D imagery, or high-motion HD content, contrast is often the only way to capture the subtleties of what client may have painstakingly created.
As spelled out in the standard, AV professionals who want to achieve the optimal contrast ratio should go through a series of simple processes, including preparing a viewing area plan that describes screen details and five possible viewing locations in the room. (The standard comes with sample viewing plans). They then follow five specific steps to measure and record luminance values from the different viewing locations. This measurement process is repeated for a venue’s different lighting environments based on the client’s viewing requirements.
After recording the resulting contrast ratios, the technician can determine whether the projection system conforms to one of the standard’s four minimum contrast ratios based on the type of viewing and the lighting in the room.
“The standard is meant to help take some of the worry out of setting up projection systems that meet clients’ expectations,” says Joseph Bocchiaro III, Ph.D., CTS-D, CTS-I, and InfoComm Vice President of Standards and Best Practices.
Publication of the standard is just the beginning. As AV professionals in both installed systems and live events use the standard more, it will inevitably raise the level of projection systems. And while it may be too early to envision clients specifically requesting systems that meet an image standard, according to Stimson, the fact that the standard exists — and that it is an ANSI-approved American National Standard — increases the likelihood.
To obtain a copy of the ANSI/INFOCOMM 3M-2011 Projected Image System Contrast Ratio standard, you may purchase it from the ANSI eStandards Store, along with InfoComm’s other ANSI-approved standards, ANSI/INFOCOMM 1M-2009, Audio Coverage Uniformity in Enclosed Listener Areas and ANSI/INFOCOMM 2M-2010, Standard Guide for Audiovisual Systems Design and Coordination Processes.