It's All in Your Presentation

By James Chan

Every idea. Every strategy. Every plan. Each one gets the proper attention when it's presented well. Thanks to electronic display projectors, now presentations can be their best. Tools like these help presenters make their points more effectively, send these messages with flair, and communicate with impact.

Projectors: A Buyer's Guide

Let's begin with the term brightness. Brightness is expressed in American National Standard Institute (ANSI) lumens, a standard unit of measurement that enables different projector brands to be measured and compared fairly. Although it's one of the most important features to consider before buying a projector, brightness remains a rather elusive standard since it's largely a function of a projector's lamp, lens and optical engine. As such, it varies from projector to projector, even among those of the same make and model. (Brightness even varies in a single projector, depending on the age of its lamp.) Projector manufacturers worldwide face this challenge in a very real way, which explains why brightness specifications are referred to as typical, not guaranteed. These specifications can vary +/- 20 percent depending on the luck of the draw, so they shouldn't be regarded as hard, factual numbers. Specifications are simply a benchmark for fair comparison with other projectors. As a general rule, however, brighter is usually better. Determining how bright is bright enough depends on a few factors.

Contrast ratio

For the majority of projector users, brightness is the most important factor. For someone planning to display more movies and videos, the most important consideration is contrast ratio, the ratio of the brightest white versus the blackest black. The higher the contrast ratio, the deeper and richer the colors are displayed.

Although there's also an ANSI standard for measuring contrast ratio, most manufacturers opt for the de facto industry standard, the Full ON Full OFF measure. Using the same 40-inch diagonal 4:3 aspect ratio screen, a white screen is projected and its brightness is measured from the center. Then a black screen is projected and its brightness is measured, again from the center. The contrast ratio is the ratio of between the two measurements.

XGA vs. SVGA

Resolution pertains to the number of picture elements, or pixels, that make up your screen area. If you've gone shopping for a digital camera or a desktop monitor before, you probably have a basic understanding of resolution. Here's a breakdown of known resolutions in computer graphics:

It helps to understand that computer screens are fixed in size. Therefore, a higher resolution doesn't make the display any bigger. It simply shows more information in smaller sizes, so higher resolution is not always better. Sometimes higher resolution even backfires by making the objects look smaller on the screen. In short, don't be enamored of a higher resolution if it's not necessary for your intended applications.

Unlike your desktop CRT monitor, a projector is a single resolution display device, and this singular display resolution is called its "true" or "native" resolution. Although it will also display other resolutions, it doesn't display them in true fidelity. In other words, if you buy an SVGA projector, it only displays SVGA resolution with a true one-to-one pixel ratio, enabling your displayed screen to be at its sharpest and clearest possible. When you display a VGA, XGA or even SXGA screens in an SVGA projector, they'll still be displayed, but images will be compromised because of the expansion or compression involved. For example, if you're displaying a VGA (640 x 480) computer screen on an SVGA native projector, the image will not be big enough to cover your entire screen. Therefore, the projector expands the image proportionally to fill the screen. Similarly, if an XGA (1024 x 768) computer screen is being projected using an SVGA native projector, the higher resolution screen has to be compressed to fit into the SVGA (800 x 600) screen. Otherwise, portions of the higher resolution screen will be cut off from the display.

The resolution you choose depends on which materials you plan to present the most. It helps to know that the current most popular resolution level is XGA (1024 x 768), followed closely by SVGA (800 x 600). XGA is popular because almost all high-end notebook computers come standard with XGA screens, and most turnkey application software packages use XGA as the standard resolution. If you're projecting computer applications, XGA will be necessary to show a full screen of the application. SVGA, on the other hand, is popular because of its affordability. Entry level notebook computers still come with SVGA screens, and almost all Internet homepages are designed using SVGA as standard resolution.

So, which resolution is best for you? If most of what you present is PowerPoint^® or similar computer-generated slide presentations, save some money and buy an SVGA notebook computer and projector. If you're planning to display more than PowerPoint^®, consider XGA resolution at least. If you already own a notebook computer, always match the resolutions of your projector and computer.

A word about LCD and DLP^®

The two most popular technologies fueling the growth of electronic projector displays are miniature Liquid Crystal Displays (LCD) and Digital Light Processing (DLP). To imagine an LCD projector at work, visualize an image forming electronically on each of the three LCD panels as though they're digitized slides. Then, with light blasting through them, a converged image is projected through the lens and magnified on the screen. DLP^® is a reflective technology based on digital micro-mirrors on a chip. Each DLP chip features hundreds of thousands of micro-mirrors. Each mirror represents one pixel, so an XGA projector (1028 x 768) will have 1,028 mirrors in each one of its 768 rows. To form an image, each mirror tilts to a varying degree, reflecting the proper amount of light for each pixel represented in an image. A constantly turning glass wheel with red, green, blue and clear transparent colors gets in the way to form the colors needed.

Not withstanding mobile projectors, the DLP chip also powers the engines of many other display products, including projection televisions, cubes that form video walls, and even large-venue movie projectors. DLP projectors are usually small and light, and because of their reflective nature, those with lamp power and size similar to an LCD counterpart are often brighter and yield a higher contrast ratio.

Between the two most popular technologies--LCD and DLP^®--it's a toss-up as to which one is a better choice. Both technologies undergo constant improvements and each has its benefits. Do some side-by-side comparisons and buy the model your eyes tell you is better.

How are colors evaluated?

As important as color is, it's often not scrutinized enough when buying a projector. Many buyers rush to the conclusion that brightness matters more than anything else, then they buy accordingly. However, many projectors quest for high brightness when showing a white screen, causing them to overcompensate on blue, which typically makes a word processor or a spreadsheet look good. Flesh tones, on the other hand, look like they've been through the wash cycle.

Before you buy, examine how each model lets you adjust its colors. Are there adjustments for each of the major color inputs (red, green and blue)? High-end projectors are even more sophisticated. These allow you to adjust a color down to its gamma level, but inexperienced users who don't understand these adjustments tend to hurt a picture more than they help it.

Also, can the color temperature be adjusted to shine best with the lighting of the intended room? Or can it be tuned to suit the kind of applications shown mostly using the projector? In rooms with high ambient lighting or incandescent lighting, a higher color temperature shows colors more vividly. In rooms with primarily white fluorescent lighting, however, it's best to tune the projector with a low color temperature. This makes the picture look warmer, despite being flooded by bluish-white fluorescence.

Color temperature has a profound effect on how your applications appear on the screen as well. If your applications show mostly on a white background, or on varying shades of white, a higher color temperature makes your whites look somewhat whiter. However, if intense displays involving natural colors and flesh tones are the plan, a warmer color temperature setting is usually recommended.

Let's go shopping!

If you're a first-time projector buyer, always buy from someone who can demonstrate all of a projector's features. Professional audiovisual dealers can show you a few different models. Since they operate on relatively low margins, most computer resellers and Web stores are not equipped to handle such an old-fashioned way of selling. These are, however, good sources for your second--or next 20--projectors.

As a first-time buyer, it's also important to keep an open mind. When looking for ultra-portable or micro-mobile projectors, give yourself an allowance of up to two pounds; you'd be surprised at the brightness and richness two pounds more can offer.

It's also wise to give yourself an allowance of up to 500 ANSI lumens. Although the difference in brightness may not be visible to the naked or untrained eye, in a semi-lighted environment or totally dark room, these extra lumens may actually offer better contrast ratio and colors--and save you a few hundred dollars too.

James Chan is the Senior Product Manager of Presentation Projector Products at Mitsubishi Digital Electronics America in Irvine, Calif. E-mail Chan at jchan@mdea.mea.com.

Time to Buy?
Terms to Know Before You Go

By Dan Zubic

A projection system is more than a bunch of specifications and features. It's a tool that can make your worship service more intimate and dynamic. Brush up on technical jargon before you view spec sheets and talk to dealers.

ANSI lumens

Projectors measuring less than 1000 lumens can be used in small rooms with little environmental light. For church classroom or conference room applications, projectors of 1000 to 2000 lumens are recommended. It's not necessary to turn the lights off with a projector of this brightness, but a reduction in room light will result in better screen viewing. For large conference rooms and classrooms as well as small church spaces, a projector in the 2000 to 3000 lumen range will do the job. However, most large church spaces want a high light output projector of 3000 ANSI lumens or more. Churches need a projector with a relatively high light output in many cases to combat unavoidable ambient light coming from windows.

Blending/Scaling

This occurs when a projector displays an image by converting it its own native resolution. In projectors with good blending (or "scaling") systems, images can be blended to one higher or lower resolution--from XGA to SVGA or SXGA, for example--without a serious degradation in image quality. Blending to two resolutions away--from SVGA to SXGA, for instance--tends to result in less than perfect images, even in projectors with high-quality scaling systems. Many laptops feature XGA native resolution, so churches will want a projector with a minimum of SVGA resolution to be compatible with today's technology. If economically feasible, purchasing an XGA resolution projector offers better compatibility with laptops and more protection against future obsolescence, as future technologies may be higher in resolution.

Inputs

The projector should come with several inputs that increase its flexibility regarding images it can display. Any projector you by should include the following inputs:

• Component Video--This type of compatibility is necessary to show HDTV as well as professional video.
• RGB--(Red, Green and Blue) These are the basic signal components of the computer's output. This compatibility is necessary to display computer signals.
• Video, S-Video--These are common video standards you'll need.

Keystone Correction

This feature corrects images if the projector is projecting from an offset angle. It should be included in any projector you plan to use from a desktop. Fixed installation projectors, if installed correctly, shouldn't require keystone correction.

Lens Shift

This feature of high-end projectors allows you to simplify setup by moving the lens and relocating the image to the desired position without moving the whole projector.

Native Resolution

Resolution is the measure of the number of small squares, called pixels, that the projector uses to create an image. More pixels equals higher resolution, and higher resolution equals a more detailed image.

Monitor Output

If you're purchasing a projector for classroom use, a monitor output allows you to hook up a monitor to the projector and use the monitor as a teleprompter. This means you won't have to turn your back to the class to see what's projected on the screen.

RS232 Controllability

An RS232 control operates several systems simultaneously from a single remote, including the sound system and projector. For this integration to occur, the projector and the other components must all be RS232-controllable.

Video Compatibility.

This term refers to the types of video signals that the projector can project.

NTSC

(National Television Standards Committee) This is the standard signal for broadcast color television and other video equipment in North America. It is important that the projector be compatible with this standard.

PAL

(Phase Alternate Line) This is the standard used in Western Europe. Many projectors feature this compatibility, but it's not necessary for church applications in the United States.

SECAM

(Sequential Couleur Avec Memorie) This is the color television standard used in France and Eastern European countries. Again, it is not necessary for most North American applications.

Zoom and Focus

These features allow the user to perfect the image size on the screen and eliminate fuzziness without moving the projector. Zoom and focus should be included on any projector you buy.

While this information helps, you will ultimately need to rely on a reputable dealer to help choose and install your projection system. Ask other churches in your area for recommendations and be sure to schedule a demonstation before you buy. Schedule it in full light of day, when uncontrollable ambient light is at its peak. This is when you'll be holding services and you'll want to know your projector is bright enough.

As Projector Product Line Manager for NEC Technologies Visual Systems, Dan Zubic oversees the business and product development of the company's entire projector line. In this capacity, Zubic also heads the company's product management team for projectors.