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DVDO iScan Duo Video Processor

Powerful External Processing: Is this a Radiance-killer?

Anchor Bay has just released an update to their popular DVDO iScan Duo external video processor that provides it with new powerful video calibration capabilities. At an MSRP of $1299 and street prices at around $1000, this is a surprisingly affordable option for those looking for world-class video scaling, deinterlacing, processing, switching (it has eight 1.3 HDMI inputs and two HDMI outputs plus a host of analog inputs) and custom calibration controls. In this last regard, the Duo offers an 11-point gamma/grayscale adjustment and a color management system (CMS) that provides control over the saturation and hue of the primary colors. This is a particularly useful feature for displays with inaccurate color, which is to say most displays. Unfortunately, it does not currently offer independent control of the secondary colors or any control over color luminance. Nonetheless, the additional of even these calibration controls substantially adds to the value of the product and its ability to make a real, visible improvement to image quality.

Duo and the Radiance

The only other comparable product on the market is the $3499 Lumagen Radiance XS. So, to answer the question posed above "Is the iScan Duo a Radiance Killer?" I would say MAYBE. I say this as a Radiance owner and a big fan of Lumagen. Until now, it has been the only full-featured video processor that offered a full range of calibration controls. The only real problem with the Radiance has been cost. At over 3-thousand dollars this unit is more expensive than most commercial displays. As such it remains a boutique item reserved for a relatively small niche market of well-healed video enthusiasts. However, with the Duo selling on Amazon for $999, external processing and extensive calibration controls are within the reach of a much larger market.

The question is whether at this price point it can match the Radiance's performance? In at least some ways, the answer is clearly yes. As a processor/transcoder/switcher the Duo gives up nothing to the best that's available. The proprietary ABT2010 processing chip used in the Duo is arguably the best in the business. The Duo's user interface is actually significantly better to the Lumagen's rather primitive DOS-like approach. The basic image quality from both is impossible to fault, though I thought that the Duo did a somewhat better job with SD material. But to be clear, the difference is small and both pass all of the standard deinterlacing tests contained on the HQV Benchmark disc.

The one area where the Radiance clearly has a leg up on the Duo is in their respective CMS implementations. One difference between them is that the Radiance offers an RGB mixing approach to color management. The user changes the RGB values for each color as a way of changing that's color's hue, saturation, and lightness. The Duo, on the other hand, uses a more straightforward approach. Although the color calibration probably works similarly behind the scenes, the user does not directly interact with the RGB mixing. he or she simply adjusts xy color coordinates up or down to change the selected color's saturation or hue. So, for example, if a green measures x0.578, y0.679, you would adjust x up and y down to match the HD standard of x0.300, y0.600. The changes you make are reflected in real time on the screen. All the user needs is either a continuous read-out of the raw xy values (and knowledge of what the proper targets are) or a CIE chart that continuously plots the color targets and measured values. The Duo approach is unusual, but I found it very easy to use—easier in fact than the RGB controls on the Radiance.

The only problem with this, as I mentioned above, is that the Duo offers no control over the secondaries or over the brightness of any of the colors. This may or may not be a problem depending upon what type of color errors your display suffers from.

The Duo in Action

I tested the Duo's calibration controls on a Pioneer PDP-5060 Kuro plasma. First, I set the user controls at their optimum settings. Even after this, the standard Kuro's performance is limited by oversaturated reds and greens, a slightly reddish grayscale, and a gamma that is reasonably flat, but too low.

First, I used the Duo's 11-point RGB grayscale controls to correct the slightly reddish white point. Here are the results.

As you can see, the grayscale was blue-deficient before and nearly perfect post-calibration. I could have lowered the dEs even further by another round of adjustments. Like any calibration procedure, this one is reiterative. You can always get better results if you spend more time with it, but with 10 separate controls to adjust, each iteration becomes quite time-consuming. In the end, I cut the average white balance error from a small 3.8 to an invisible 1.1. What this chart doesn't show that the white balance error even at 10% was an invisible 1.4 dE.

Next, I proceeded to tackle the errors in the gamut. Here is the dE report showing the results of the effort.

Next, the same data broken out into HSL components.

Finally, a standard CIE chart.

This data sows that with the available controls, I was able to reduce the average color error by more than half. The green error was cut by nearly 90%. The remaining errors worth mentioning were in areas where you would expect—secondary hues and blue, red, and magenta lightness. Notice, though, that secondary saturation was quite good, despite the fact that the adjustments in the Duo gave me no direct control over them. This is because the secondary colors are derived from the contributing primaries. Get the primaries right and the secondaries should fall into line. It is worth noting that Lumagen's one attempt to provide a CMS in an affordable product largely failed in this regard. The now-discontinued HDP processor also lacked secondary control, but adjusting the primaries actually had a negative effect on the secondaries, substantially desaturating them beyond their intended targets. The Duo suffers from no problems of this type.

Finally, let's look at the effect on the gamma response.

The controls worked exactly as designed, although this was one area where I felt as though the Duo could improve on its user interface. The method to adjust gamma is to simply raise or lower all three of the RGB controls by the same amount. That means three adjustments at nine points. It's a lot of work. Furthermore, for some reason I had to repeat the process several times to get the desired result. The Duo could make this process much easier by offering an ALL control in addition to the individual RGB adjustments. Having such a control (the Radiance offers this) would speed up gamma adjustments substantially because now there would be only one adjustment for each of the nine points.

Conclusion

The bottom line? If you are in the market for a full-featured video processor, the iScan Duo is an excellent choice, as is the even lower-priced Edge that DVDO offers. Alternatuively, if your display has otherwise uncorrectable grayscale or gamma errors, then iScan Duo is a nearly a perfect product at an attractive price point that will completely remedy these issues. Finally, if your display has otherwise uncorrectable errors in the color gamut, but good color decoding, then the iScan will allow you to remove the great majority of those errors. The one context in which I cannot recommend the iScan Duo is for displays with color decoding errors or simple design flaws that will require adjustments of the secondaries and color luminance values (the vast majority of color decoding errors manifest themselves as errors in primary brightness and secondary hues).

Except in those special cases, I believe that the iScan Duo is a breakthrough product. It is the first fully-featured external video processor to offer such a powerful mix of calibration controls that work as they should. Will it be a Radiance killer if and when it gains additional functionality in its CMS? Absolutely.

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