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Silicon Image iScan Pro Progressive Scan Video Converter  Print E-mail
Home Theater Video Processors & Switchers Video Processors
Written by Bryan Southard   
Saturday, 01 September 2001

Introduction
The iScan Pro is a progressive scan video converter, a product better known in the industry as a "line doubler." Line doublers are devices designed to improve the visual appearance of video displays and projectors, limited to those that can accept the higher scan rates found on many front video projectors, high-definition rear-projection televisions, plasma TVs and computer monitors. This improvement consists of increasing the scan rate, which creates a smoother and more film-like video presentation.

To comprehend how the iScan Pro works, you should first understand some basics behind what makes televisions and video projectors tick. Until recent years, all televisions, even front video projectors, were cathode ray tube (CRT) based. This technology has been a part of our lives since the invention of the television some 50 years ago. This technology works by projecting horizontal lines in front of the picture tube.

CRTs are capable of presenting 480 visible scanned lines, a number that the NTSC, the governing body, had determined to be plenty good in order to produce a great picture. The problem is that this standard was decided upon back when televisions were quite small, most often no more than 12 inches, measured diagonally. The NTSC was right in its day. The technology did produce a solid picture, but as the size of televisions increased to 27 inches and larger, horizontal scan lines became very apparent.

In recent years, both front and rear-projection video have become very popular. Screen size has grown to 100 inches and more, with the use of big gun CRT front projection. At these larger sizes, the spaces between the horizontal scan lines are not only apparent, but become an object of focus. This condition is only exacerbated by the near-screen viewing positions that many of us live with due to the layouts of our home theatre environments. In addition to the presence of black spaces between the horizontal scan lines, diagonal lines have by default become stair-stepped and jagged.

CRTs, which includes rear-projection or "big screen" sets, have an interlaced signal with a scan rate of 15.734 kHz, which represents the number of scan lines reproduced per second, i.e., 15,734 lines per second. Today’s newer video appliances, such as front video projectors, rear-projection HDTV-compatible sets and plasma screens, are capable of accepting much higher scan rates, which means they can accept the progressive signal minimum of twice the standard 15.734 kHz rate, or 31.5 kHz signals.

A 15.734 kHz display scans 240 active lines per pass, taking two passes to regenerate 480 lines of information. What a "doubler" does is double the frequency to 31.5 kHz, converting the signal from interlaced to a progressive computer signal, thus scanning 480 lines per pass. What this does when implemented correctly is smooth out images, removing much of the stair-stepping of diagonal lines and making video look considerably more like film.

The Silicon Image iScan Pro is a pint-size enclosure measuring approximately five-and-three-quarters inches wide, one-and-a-half inches tall and eight-and-three-eights inches deep, weighing just over one pound. This piece is as small and light as your average paperback book. The iScan Pro outputs its video signal through a 15-pin d-sub connector, exactly like the video monitor connector on the back of your home or work computer. To connect it to your video device, unless your set accepts this connection as many newer sets will, you will need to purchase an adapter which will convert this 15-pin connector to RGB or Component Video connections, depending on your systems requirements. For source inputs, the iScan Pro has Component Video, S-Video and Composite Video connections. The face of the unit has an input selector switch for selecting your source connection method, an RGB or YpbPr switch to select the method of connection to your set, and a normal or squeezed selector switch for correcting older 16x9 rear-projection sets. Today, most video devices that will accept a progressive signal do not require this correction. There are image adjustment knobs for brightness, contrast, color saturation, hue and sharpness control. The unit comes in an attractive black wrinkle-finished enclosure with rubber feet and retails for $899.

Today, with the emergence of many high-end TVs, line-doubling progressive scan converters are becoming much more commonplace. In years past, these devices were limited to the extremely affluent who could afford $50,000-plus video systems. In the present, you can purchase a DVD players with a progressive output, a product that was once very expensive but is now available for as little as $400. There are also higher-end DVD units with licensed 480P technology that are available at a much higher price.

The considerable advantage of running a separate progressive scan converter, such as the iScan Pro, rather than a DVD player with a progressive output, is that the outboard unit allows you to connect multiple devices, such as satellite or cable television, DVD and Laserdisc players, VCRs and even a Sony PlayStation 2. This makes outboard devices considerably more appealing to me.

After I connected the iScan Pro via its separable wall plug power supply, my projector needed a complete re-setup. This will be the case with all older video projectors, due to their inability to automatically compensate for the increased scan rate. Set-up consists of adjusting the picture limits, convergence and all other aspects of the screen image. For those who need this, it may be a challenging adventure but also a worthy learning experience. Others may want to consider hiring a professional to perform this detailed and specialized task. If you plan to perform this job yourself, I recommend the Avia "Guide to Home Theater" set-up disc (Ovation Software). This disc has a step-by-step tutorial for the set-up of your video gear, as well as every other aspect of your theater and audio system.

I am currently running an older Sony 1270Q CRT front projector, projecting onto an 84-inch diagonal screen, a number that once meant something as it refers to the diagonal dimension across a 4:3 screen, but now means very little with the emergence of 16x9 and anamorphic formats. I prefer to describe the size as 67 inches, which is the horizontal dimension across the screen.

I view my screen from a distance of approximately nine feet away. Scan lines, or black spaces between the scanned lines, are very apparent with the interlaced or un-doubled video signal. Diagonal lines appeared jagged and distorted, making DVD movies appear more like video than film.

The Movies
After connecting and adjusting the iScan Pro, I was excited sit down with some movies and evaluate the performance of the equipment. The special edition release of Platoon (Orion Pictures) landed in my DVD player. I had taken this emotional journey through the jungles of Vietnam just before connecting the iScan Pro without the aid of a line doubler connected to my video projector in order to reference the untreated interlaced presentation. With the iScan Pro, images such as the darker treks through the jungle marsh became much improved. Typically, dark distant scenes are much more susceptible to poor video quality than those filmed in broad daylight. In the scene where Elias is emerging from the woods to be confronted by the murderous Sergeant Barnes, what had appeared fragmented with edge motion artifacts had now become smoother and much more film-like. Rather than focusing on the flickering of light caught in between the scan lines, I could focus on the content of the movie – a vast improvement.

In the Eagles' musical presentation Hell Freezes Over (Geffen - DTS), video images that I had considered to be frustratingly poor, when viewed with the untreated interlaced signal, were now considerably improved. In the opening number "Hotel California," scenes that were filmed from afar had previously looked jagged and unclear due to the fact that the smaller images had fewer horizontal lines, with the black scan spaces consuming much of the image. With the iScan Pro, this effect was very much reduced. Diagonal lines were not perfect, but were improved enough to for me to enjoy the video presentation. Without the iScan Pro, these diagonal lines would capture light or, more accurately, the presence of blackness between the scan lines would cause the light surrounding the images to become intermittent and appear unnatural. This was again much improved with the iScan in place. Close-ups continued to reveal some motion- and edge-related artifacts, but overall the picture was vastly improved.

Will this product work for me?
In order to run the iScan Pro, your equipment must have a minimum frequency acceptance of 31.5 kHz. This includes most new HDTV-compatible sets and virtually all front-projection systems, including CRT, LCD, DLP and the emerging D-ILA technology. If you are unsure whether your set is compatible, you can visit the Silicon Image webpage listed at the bottom of this review for a complete listing. Nearly all DLP and LCD projectors come with built-in 480P converters, but these are for the most part very low-quality processors, whichh can cause undesirable image artifacts. In many cases, you will find considerable improvement with the use of an outboard progressive scan converter. This product also works with computer video monitors. In some cases, a computer monitor can be used in your video system to cue a movie prior to turning on your video projector or, in other cases, the iScan Pro can be used to supply video images to your work or home computer monitor.
Downside

The iScan Pro is a relatively inexpensive high-performing progressive scan converter and consequently provides a minimum of input connections. This may be adequate for many users, but for others, it won't be enough. In situations where more is required, you will need to consider outboard switchers and or adapter cables, which in some cases will negatively affect the performance of the product.

Almost anyone who owns a television or monitor that is compatible with the iScan Pro will want to run RGB cables in order to get the best possible picture, but the Iscan Pro does not provide this input, or for that matter, even an adapter. You will need to understand your set’s requirements and purchase an adaptor that will work for your application.

Although many may like the diminutive size of the iScan Pro, I found it to be something of a nuisance. Because most quality RGB and Component Video cables are very rigid -- I have the hose-like Premium RGB from Transparent -- I had to place a sandbag on top of the unit to keep it from being pulled off the rack shelf where I had placed it.

Conclusion
The iScan Pro is a device that will improve most compatible video sets. It will provide smoother and much more appealing video images. If you are running a CRT front projection system without a doubler, you will be pleasantly surprised with what this little box can do for you at a relatively inexpensive price. There are many other progressive scan converters that cost more -- in some cases, as much 20 times more -- and are capable of supplying video processing that is superior to that of the iScan Pro. However, it is absolutely fantastic for the iScan Pro to provide such a high level for such a relatively minimal cost. I won’t insult you with the standard line, "You might want to audition this product before you lay down your hard-earned dollars on the purchase price." But I will say that if you want improved performance from your compatible television or projector, and you either don’t have mega-dollars for today’s best or have decided not to spend it, here is you’re alternative option, and it's a damn good one.

Video processing technology is on the move, but for that matter, so is every other aspect of home entertainment. The current trend for video processing is moving towards Scalers, such as my personal reference, the Faroudja NR Series Scaler (ranging in price between $4,000 and $5,000, depending on configuration) which can optimize to the best possible resolution (i.e., the native rate) that your video system can handle. This is specifically of value for D-ILA and DLP digital video projectors.

If you have a compatible front- or rear-projection television, a plasma display, or a home- or work-oriented DLP or LCD projector, and you are not running an outboard 480P converter, take a look at the iScan Pro. Great video is addicting and this product just may be your fix.
Manufacturer Silicon Image
Model iScan Pro Progressive Scan Video Converter
Reviewer Bryan Southard





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