Projecting An Image: LCD vs. DLP

LCD (liquid crystal display) projectors contain three LCD panels for red, green and blue video, which are combined to project a color image. As light passes through the LCD panels, individual pixels can control whether light is passed or blocked to construct the image. The light itself is provided by an ultra-bright lamp in the projector.

DLP (digital light processing) technology was developed by Texas Instruments and works very differently from LCD. DLP technology uses a reflective surface made up of thousands of tiny mirrors. Each mirror represents a single pixel, and light is bounced off the mirrors. The reflected light then travels through a color wheel that consists of red, green and blue filters. The spinning color wheel directs colored light to the DLP chip, which then reflects the light into the lens to project an image. The individual mirrors tilt away from or into the light path and control how much of each color is projected.

Each of the technologies offers advantages and disadvantages. Until recently, LCD technology reigned supreme when it came to color saturation, but advances in DLP technology have narrowed that gap. However, LCD still offers better color saturation than DLP when compared at equal lighting levels. On the other hand, DLP projectors can be designed to cast a brighter image, but at the expense of color saturation.

With equal lamp wattage, LCD will provide a brighter, sharper image than an equivalent DLP projector, although it really takes a keen eye to notice the LCD upper hand.

LCD-based units have their weaknesses, one of which is pixilation, or the ability to see the individual pixels on the screen. Another weakness is often referred to as the “screen-door” effect, which is the result of blank spaces between pixels (called the inter-pixel gap), thus making the image look as if it’s being viewed through a mesh screen. Although those problems have become less noticeable as resolutions have increased, DLP, for the most part, still holds an advantage over LCD with reduced pixilation at any resolution. DLP also offers superior contrast ratios with DLP projectors, often exceeding contrast ratios of 1,500:1, while LCDs tend to achieve half that ratio.

One more problem associated with LCD technology is age-related image degradation. Over time, LCDs have the propensity to lose contrast and color saturation. Typically, DLP proves to be economical and portable—great for the traveler—while LCD offers better light output per pound and improved color saturation, making the technology ideal for larger venues.

With this debate in mind, the CRN Test Center took a look at two projectors, a PJ452 LCD projector from ViewSonic and a XD460U DLP from Mitsubishi. At first blush, both of these units appear quite different. The PJ452 is clearly designed as a lightweight portable unit, which is rare for an LCD-based unit. The XD460U proves to be a bit larger and heavier, which seems rare for a DLP unit.

The ViewSonic PJ452 is 4.2 pounds and boasts a bright image of 1,500 lumens. Native resolution is 1,024 x 768 (XGA standards) and pull down is 3:2 for compatibility with HD wide-screen formats. A contrast ratio of 300:1 proves to be adequate for most viewing circumstances, and its advanced design eliminates screen-door and pixilation effects. Test Center engineers found that at an MSRP of $999, the unit offers excellent balance between image quality, portability and affordability.

The Mitsubishi XD460U, on the other hand, has an MSRP of $5,495 and features that are clearly aimed at the home-theater market. The XD460U proves to be blindingly bright, with an ANSI lumens rating of 2,500 and a crisp 2,500:1 contrast ratio. That combination of brightness and contrast makes the unit ideal for viewing live-action, high-definition video. The unit’s native resolution of 1,024 x 768 (XGA) and image ratio of 4:3 is somewhat of an oddity for a theater-style unit; Mitsubishi eschews the wide-screen format (16:9) that is commonly used for theater-type broadcasts. Even so, Test Center engineers were impressed with the brightness and overall image quality offered by the unit.

Is the XD460U worth five times the price of the PJ452? In a single word, no. It all comes down to where the projector is to be used and how. For ultra-bright high-contrast images, the PJ452 can’t hold a candle to the XD460U, and for value and portability, the XD460U can’t compete with the PJ452. So, in summation, just like in the cola wars, the choice simply comes down to a matter of personal preference.