External Video Processors

These great little devices, also known as "scalers", offer videophiles a relatively simple (though not cheap) way to improve the performance and simplify the connections of an existing home theater without requiring any changes to an existing installation.

These devices improve performance in four ways:

• Scaling: A processor will take the output of your existing device, typically 720x480 or 1920x1080, and then scale the signal to the native rate of your display, 1280x720, 1366x768, or 1920x1080. For this to work your display must have a setting that allows you to bypass its own internal scaling. This option is often called "Native" or something like this. This doesn't really apply to analog displays that have no native scan rate, though CRTs will often perform best when fed a specific resolution. With the recent proliferation of 1080I/P sources and 1080P displays, scaling is less important than it once was.
• Deinterlacing: This is the area where an external processor can make a significant difference to your image quality, especially for high-definition signals. Very few displays have circuitry built into them that properly deinterlace 1080i sources. If you have a digital 720p or 1080p display, you can significantly improve your picture quality by using a processor that takes a 1080i signal and deinterlaces this source into a progressive format while retaining all of the resolution of the original. This is less important for 480i sources because there are many existing progressive scan DVD players that perform an excellent job deinterlacing 480i.
• Calibration: Many displays include the ability to adjust gray scale, color decoding, and geometry. A few even offer color management. However, most do not. For those displays who lacks built-in calibration controls, an external processor can be an invaluable tool for helping the display to achieve optimal performance. In fact, the calibration tools of a processor can often have a much bigger impact on the perceived image quality than their core scaling and deinterlacing.
• Switching and transcoding : Many home theaters, especially those that use front projection, can be difficult to install when you have several sources you wish to connect to a ceiling-mounted device. An external scaler solves these problems, because you connect all of your analog and digital sources to it, and then run just one HDMI cable from the processor to your projector.

As you can probably tell, I'm a huge fan of external processors. Their only downside is that, because they serve a relatively small high-end market, they are generally quite expensive, typically in the range of $1500-$4500. However, if you can afford it, I've never seen an installation that didn't benefit from the addition of such a device.

So, you are probably wondering, what do I recommend? I can recommend the following external video processors:

Lumagen VisionHDP ($1199): This unit offers true 1080i deinterlacing and includes extensive calibration adjustments. These include an impressive 11-point gamma and grayscale tool, and recently Lumagen added Color management as well. However, this does not work nearly as well as what's offered in the radiance (see below). Its weaknesses are that it offers no HDMI inputs (DVI only, though you can use an adaptor), and its user interface is a very clunky (text-based, almost DOS-like).

Calibre Vantage HD ($2799): This unit is based on the Realta HQV processor. It offers true 1080i deinterlacing and includes modest calibration adjustments. Of all the processors I have seen this one puts up the best HD images. HD cable is noticeably improved, and HD DVD looks breathtaking (though it looks really good even without the processor). Its weaknesses are that its film-based 480i performance is not as good as other units (video-based material looks great). Indeed, I prefer running a 480p signal from a good progressive scan DVD player into this device.

Optoma HD3000 ($2999): This processor is based on the Gennum VXP processor. It offers a really nifty user interface, true 1080i deinterlacing, and includes extensive calibration tools. This unit's weakness is that its HD performance is not quite at the level of the Realta-based Vantage.

PixelWorks Crystalio II ($4500): This is another Gennum-based VXP processor. It offers true 1080i deinterlacing and includes extensive calibration adjustments, second only to the Radiance. These adjustments include a color management system that, while not quite in the league of the Radiance, can greatly improve the display's color performance. This unit has a very sophisticated user interface and offers good performance. It's biggest weakness is price. However, Pixelworks offers another unit, the VSP3100, that costs about the same as the Vantage and Optoma . It achieves this cost reduction by leaving off the analog output. If your display needs only digital inputs, this is an excellent choice.

DVDO VP50Pro ($3499): The VP50Pro is DVDO's flagship video processor. It supports inverse telecine and motion adaptive deinterlacing for 1080i sources making its core processing fully competitive with the Realta and Gennum-based units. It also offers sophisticated noise reduction circuitry for substandard sources. Its core deinterlacing, scaling, transcoding, and switching are first rate. Its biggest weakness is the fact that it has virtually no calibration capability.

Lumagen Radiance XD ($4495): This is a breakthrough product, though an expensive one. It is based on a newer version of the Gennum processor that drives the Optoma and PixelWorks processors. For scaling it uses an in-house solution. Its feature set is so vast that I cannot do it justice here. Suffice to say that it incorporates just about every option one is likely to need in an external video processor. Furthermore, it receives regular firmware updates, so the product is always improving. However, what sets the Radiance apart from its competitors is that it is the first to offer a fully functional 3-D Color Management System that allows a calibrator to adjust the primary and secondary color points of a display to match a target gamut. It also includes an excellent grayscale/gamma adjustment tool, which offers 11 points of adjustment much like the line of Vision processors (see above). This means that you can dial in a nearly perfect gamma curve and grayscale response through the entire visible range. The only criticism I have of the Radiance (other than cost) is that, like the Vision series, the user interface is the same DOS-like approach they have offered for years. The human interface for the CMS is also a littler harder to use than I would like. However, these are nitpicks. The image you can get with the Radiance in the chain justifies the investment for videophiles who can afford the best.

DVDO Edge ($799): This is also something of a breakthrough product, but in a different way than the Radiance. It offers an unparalleled price-to-performance ratio. The Edge is essentially the VP50Pro without custom resolutions, analog output, and a few other bells and whistles. Its core scaling, deinterlacing, and noise reduction are the same. It is interesting to see how Lumagen and DVDO's market strategies differ. With the Edge, DVDO is clearly trying to capture the low-end, which I suspect they will do. Lumagen, on the other hand, is aiming for the high-end enthusiast market. Indications are that the Radiance has taken this (much smaller) market by storm and for good reason. The Edge is a truly great buy, so long as you can live without any calibration capabilities.

The bottom line? If you can afford it, the Radiance is definitely the processor against which others will be judged. If you are on a budget and don't need an analog output, I think that the DVDO Edge is the best choice. If you find yourself somewhere in the middle and also don't need an analog output, you might want to check out the Crystalio VSP3100. If you do need an analog output, then the Vantage HD is an excellent choice. I can no longer recommend the Optoma or the Lumagen Vision. The Optoma also lacks analog outputs and offers a smaller feature set than the VSP3100 at the same price. The street price of the Vision processors compete with the Edge, but they lack the Edge's superior core processing and slick user interface.