Aspect ratio defines the shape of the projected image. An aspect ratio is the ratio of the width of the image to the height. XGA projectors have a native aspect ratio of 4:3 which means the image has 4 units of width for every 3 units of height. The source of your material will determine the displayed aspect ratio. For example, HDTV tends to be 16:9 and will be displayed with black bars top and bottom. The aspect ratio control will typically allow you to change the aspect ratio of the image by stretching it, which distorts the shape, expanding it, which retains the shape but crops the image, or displaying it in a compact form which is usually native resolution. Each projector gives you the ability to change the aspect ratio and the degree of control varies by manufacturer. Philips provides the greatest degree of control over the aspect ratio of the displayed image.

Color temperature defines how warm or cool the projected image looks and is measured in degrees Kelvin. Lower color temperatures create warmer images and higher color temperatures create cooler images. Video uses a low color temperature to give better flesh tones and more pleasing images. Data presentations use a high color temperature to maximize the light output and produce brighter images. When you connect your projector to an input source, the projector will identify your content and assign a color temperature. You might think that having a large number of color temperature settings would be a benefit; however, we found this not to be true. For a color temperature to work well, it must be optimized for specific viewing material. If it isn't, you may never find the best setting. We found that Philips and NEC did the best job of refining the color temperature.

Gamma correction, also known as degamma, affects the darker portions of an image and helps bring out detail in dark scenes when viewing video or movies. The changes are very subtle and enhance the viewing experience by better separating dark areas of the image. The higher the contrast of the projector, the greater the impact gamma correction will have. Only Mitsubishi, NEC and Philips provide gamma correction and NEC limits its use to only the User Setting, a custom setting that the user defines.

Brightness, also known as black level, is used to set the appearance of black and not light output. Brightness controls the visibility of shadow detail. Too high a setting will make the image look foggy or washed out causing lose of contrast and depth. Too low a setting will cause the loss of shadow detail. Use this setting sparingly as it is easy to optimize for one image only to have adverse affects in other images.

Contrast, more appropriately known as white level, sets overall light output and the brightness of white. Setting it too low will dim the image and too high will reduce image details. Like brightness, use this setting sparingly.

Color saturation sets the intensity of color. Too high a setting will create harsh colors that are quickly evident in flesh tones. Too low a setting will give an image a washed out look.

Hue, also known as tint, controls the amount of red or green in the image. Again, extreme settings are not necessary.

Sharpness defines the edges of objects in an image and a proper setting will improve image fidelity and preserve details by eliminating image outlines and noise. Too little sharpness can blur the edges and too much can create halos or false outlines. This control is used to soften or sharpen the edges of video images.

In optimizing the images for various uses we found that the NEC and Philips needed the least adjustment and BenQ and HP needed the most with Mitsubishi somewhere in the middle. Our primary tools for optimizing images were color temperature, gamma correction, color saturation, and sharpness with minor adjustments to contrast, brightness and hue. When making image adjustments on any projector, stay away from making large contrast, brightness or hue adjustments as they are best optimized using test patterns designed to find optimal settings. Although the manufacturers do a good job with the factory settings, they vary considerably in the support of gamma and the quality and range of color temperature.

Color temperature is one of the few controls that is truly a preference setting and, when well done, it can achieve a viewing experience you cannot attain through other settings. NEC and Philips did the best with this setting. Philips had the edge with gamma correction due to its high contrast ratio.

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5 Projector Shootout Special Features

David Colin March 5, 2004

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Each projector has some distinguishing features that help separate it from its competition. For those that like to be able to monitor video while viewing a data image, PIP (Picture-in-Picture) is available on the Philips and the BenQ. BenQ lets you position PIP virtually anywhere on the image as well as control the size of the PIP image.

NEC offers the ability to use the projector in portrait as well as landscape mode. Portrait mode is primarily aimed at the Tablet PC audience, but it is an interesting feature in that it allows you to turn the projector on its side and effectively change the projected image from landscape to portrait. Since it only turns to one side, an option to flip the image 180° is provided. Be advised that the projected image is about 50% below and above the level of the projector, the menu and screen prompts remain in their original orientation, and the keystone correction feature is not available.

PC cards enable you to store a presentation on a memory card allowing you to give a presentation without a computer. Among our test projectors, only the Mitsubishi has the built-in capability to support a PC Card and hence it is a more expensive projector than the others. HP offers a "Smart" option as an add-in that allows both the use of a PC Card and Wi-Fi 802.11 wireless support. A wireless projector allows multiple users with wireless computers to control and access the projector without a physical connection. This is a good presentation solution, but not suitable for video.

A sleep timer is a convenient way to ensure the projector is turned off when not in use. You can also use it to set the time for a presentation. Rather than a timer, NEC turns off the lamp whenever there is no source for 5 minutes.

For those that might like to use a tripod for mounting the projector, NEC and Philips both offer a solution.

Mitsubishi and HP were the only offerings that allowed you to define the startup screen with your own message. Mitsubishi allows you to use a graphic and HP allows you to use text. A slick feature for presenters as it will show your graphic or message as the projector is warming up or whenever there is no signal to the projector.

HP did a very nice job of adding some diagnostic capability including the ability to put up a red, green or blue image, and a key test for the remote control and the projector using an interactive graphic diagram.

Although all the projectors allow you to change and retain the settings on the various sources you use, NEC allows the videophile to define a custom User Setting by taking one of the predefined settings and adjusting gamma correction, contrast and brightness R, G, and B, and white peaking. Making changes at that level requires some knowledge and test patterns. Few users will find a need for that level of control.

Special Features
	BenQ PB2220	HP MP3130	Mitsubishi XD50U	NEC LT170	Philips bCool XG1
PIP	3300 positions	N/A	N/A	N/A	8 positions
Portrait Mode	No	No	No	Yes for Tablet PCs	No
PC Card	No	Yes with Smart option	Yes	No	No
Wireless	No	802.11b with Smart option	No	No	No
Sleep Timer	Up to 1 Hour	No	Up to 1 Hour	5 Minutes no Input	Up to 3 Hours
Startup Screen	No	Yes	Yes	No	No
Projector Info and Stats	Lamp Hours/Minutes Source Info	Model Version SN Current Lamp Hours Total Projector Hours	Model Number Version Factory Default Reset Lamp Timer Lamp Timer Source Resolution Source Frequency	Source Info Remaining Lamp % Lamp Usage Projector Usage Revision Level	Current Source Active Signal Format Projector Counter Lamp Counter Software Version Hardware Version
Diagostics	No	Remote Button Test Projector Button Test Color Test: red, green, blue, white, black	No	No	No
Tripod Mount	No	No	No	Yes	Yes
User Setting	No	No	No	Yes	No

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