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Part 2: The Projection Aspect Ratio Dilemma

No simple solution, but here are some hints By Gary Kayye, CTS

In a previous column , I rambled about the difficulties in connecting today's plethora of 16:9 sources (such as DVD players and new generation PCs) to regular, old 4:3 projection display systems. We learned there is no doubt that the switching of 4:3 signals and 16:9 signals to one projector is simplified -- and serves the viewer better -- if a 16:9 display is used rather than a 4:3 display.

What about when you throw in a secondary monitor or display? You might want an instructor reference monitor (confidence monitor) mounted on a podium or in the back of the room so that the instructor on the stage can see the projected images without turning around. Then there's the auditorium where you're forced to use a 4:3 projection system (because there are no bright, affordable 16:9 projection systems out there yet). But because the room's so big, you need supplemental displays for those poor souls sitting in the back of the room, 90-feet away. Do you know how hard it is to find 4:3 displays nowadays? Most of us are forced to use plasmas and LCDs - virtually all 16:9!

You've got that set of issues, again, we discussed last month in connecting multi-aspect ratio sources to different aspect ratio displays. Only now, they're doubled, as you have two different aspect ratio displays in the exact same system.

Unfortunately, there is no simple system solution, but here are some hints:

Displaying native 16:9 source material (i.e. DVD) on one 4:3 and one 16:9 display simultaneously: OK, we're starting with the toughest problem to address right off the bat -- 16:9 sources and both 4:3 and 16:9 displays. In this application, you have to be careful as selection and size of the giant 4:3 screen at the front of the room was based on the size (depth) of the room -- remember, based on the projection rules of thumb, image height is calculated as something in the range of 1/5th the distance from the screen to the last row of seats (least-favored viewer). If the 4:3 projection size was calculated correctly, you can't just assume the solution is to fill the screen with 4:3 sources and allow 16:9 sources to fill only 70% of the screen height, filling the rest of the screen with black bands. Sure, this serves the supplemental screens and the confidence monitors well enough, but it can contribute to viewer fatigue for the rest of the attendees in the room.

Consider the following possible solutions:

a. Oversize the 4:3 screen: If the application calls for a lot of video usage versus data projection (such as a church or the lecture hall used at USC's Film School), an affordable solution would be to consider specifying a 4:3 screen at the front of the room that's actually too big for 4:3 display but follows the projection rules-of-thumb when displaying the 16:9 sources. In other words, put in a screen that's just too big for the room when displaying 4:3 computer data but perfect when displaying DVDs. Although not your best solution, if the application is video-intensive, it may very well work out.

b. Specify a 16:9 screen and fill it with video and trade-off data: Another affordable solution would be to use a 16:9 screen at the front of the room and oversize the image to ALWAYS fill the screen horizontally in 16:9 projection. Remember, we're using a 4:3 projector here, so that means that when you fill the screen horizontally, you are over-shooting the screen vertically (remember those black bands you normally have in 16:9 projection on a 4:3 screen? They are now being projected onto the wall above and below the screen). Then, when displaying 4:3 material, you are using the projector's internal or external scaler to under-scan the 4:3 image so that it only fills the screen vertically (still over-shooting the image and thus, only using about 50% of the imager in the projector) so you will only get about 50% of the light output in 4:3 operation. Specify a BRIGHT projector -- twice what you would normally specify. With many of today's LCD projectors, this may present a problem when you project black, since it is still bright enough to see well, as it has more gray than black. You might instead, specify a DLP projector with blacker blacks than the LCD's gray-black. The good thing here is that there are all sorts of bright 4:3 projectors on the market -- both LCD and DLP. And they're affordable.

c. Specify a 16:9 screen and a projector with programmable zoom ratios: This is the best solution, but you will be limited today to only a few projector models -- Christie, DPI and Barco all offer programmable lens ratio projectors. As above, you specify a 16:9 screen, but in both cases, when you are projecting 16:9 and 4:3 material you will be doing it using the full imager area -- thus not limiting the light output on the screen. This is done by specifying a projector that actually has programmable zoom ratios (or RS-232 controllable zoom ratios). When setting up the application, you program the lens to fill the screen on 16:9 sources (thus still over-shooting the screen top and bottom with the black bars) but also program the lens to zoom-in to fill the screen only vertically on 4:3 sources, thereby using all the available light output!

In all three of the above applications, the 16:9 reference or supplemental monitors simply display 16:9 filling the screen and 4:3 with the black-bars vertically, or 4:3 material stretched to fill the 16:9 display area.

Displaying native 16:9 source material (i.e. DVD) multiple 16:9 displays simultaneously: This is rather simple. All you need to do is ensure that you've picked the right size screen (for image height based on the least-favored viewer) for the projected image at the front of the room. If your source material is always going to be 4:3 and you're displaying on a 16:9 projector or flat-panel monitor, all you have to do is deal with the black vertical bands on the left and right sides of the projected image. Again, image height is the key in any projected environment, so you design the room pretending the screen is 4:3. When the source material is all 16:9, it's a one-to-one match in aspect ratio. The image will always fill the screen perfectly.

Finally, the limited availability of 16:9 displays in all formats (LCD, DLP, plasma and even CRT) makes it difficult to use wide-screen systems in every application. In fact, in preparing for this article, I did a quick review of all the projector manufacturers and found that there are only nine units available that offer 16:9 native aspect ratios for projectors over 1500 ANSI lumens - a minimum light output requirement for meeting room installation in most environments. But on a positive note, even though the selection is limited, the range in light output for 16:9 projectors isn't - 1500 to 4000 ANSI lumens.

But this is a short-term problem, as all the major projector manufacturers assure me that they will all have as many 16:9 projectors by the end of 2005 as they have 4:3 projectors today!

Reprinted with permission from Sound & Communications magazine.

Gary Kayye, CTS is Chief Visionary at Kayye Consulting, Inc., a Chapel Hill, NC-based marketing consulting firm that serves the ProAV and Home Theater markets. In addition to strategic marketing consulting, Kayye Consulting, Inc. is also a training development company. Gary can be reached via e-mail at gkayye@kayye.com or through his Web site at www.kayye.com.

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Gary Kayye, CTS is Chief Visionary at Kayye Consulting, Inc., a Chapel Hill, NC-based marketing consulting firm that serves the ProAV and Home Theater markets. In addition to strategic marketing consulting, Kayye Consulting, Inc. is also a training development company. Gary can be reached via e-mail at gkayye@kayye.com or through his Web site at www.kayye.com.
Related Keywords:16:9 sources, DVD players, PCs, 4:3 projection display systems, 4:3 signals, 16:9, projector, Gary Kayye, presentation

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