Manufacturer's Report - The Whole Picture on Pioneer's Aspect Ratio - March, 1995

By Albert Margolis


When we are accustomed to a standard unit of measurement, it may become quite unsettling when someone decides to change it for any reason. Certainly this would hold true if the National Bureau of Standards decided to lengthen the inch as we know it. After all, this change could be easily supported by the fact that the inch, when originally standardized, was alleged to be the average distance from the tip of one's thumb to the first joint. Since the time of this standardization, humans have progressively become larger. This would result in an increase of this average if the N.B.S. were to take a census of this measurement today.

Imagine the amount of anxiety this change of standard would cause. All distance, while remaining the same in the absolute sense, would measure shorter. Claims by automobile manufacturers would reflect a perceived "down-sizing" in terms of MPG ratings, engine sizes, etc. All the road mile markers would have to be moved to accommodate this new inch. It would be a nightmare to retrofit society and its' mindset to think of distance in a new way.

Perhaps it is human nature to resist change of any kind that causes us to have to alter our habits. This is what happened when Pioneer adopted a new approach to accommodating the NTSC standard to meet the needs of the home theater consumer. For years, American televisions have utilized a standard aspect ratio of 4:3 (ratio of width to height). This was the ratio originally used in cinematic presentations and subsequently was adopted by the NTSC when television was developed. Growing up with this aspect ratio, I personally assumed that my television picture reflected all the information that the TV station was broadcasting. As it turned out, on average, 10% of the information is masked out of the TV picture tube by a process called overscanning. Using this method, the portion of the picture that is typically out of focus along the edges is hidden. The edges of the picture are particularly difficult to keep in focus because this region of the CRT is where the electron gun is at its maximum point of arc with respect to scanning the image across the surface of the picture tube. These extremes of angular shift correspond to voltage swings which are regulated by the TV's power supply. The better the power supply, the more in focus the edges of the picture can be. In a projection TV, this effect is exacerbated since there are three CRTs in which these voltage shifts need to be regulated. This boils down to the fact that it is easier, and less expensive, to manufacture a television with a lower quality power supply and simply overscan the out of focus edges.

Pioneer has taken a different course. Because of its history as an audio manufacturer, Pioneer designs projection monitors from an audio perspective. Just as good power regulation is imperative to good audio performance, it is equally important to video performance. High quality power supplies have allowed the Pioneer projection monitors to reveal more of the edges of the picture because less of the edges are out of focus, and thus, less overscan is used. Proper lens, mirror, and focus circuitry are also involved in obtaining these results. This is not a new practice for Pioneer; indeed, we have been doing it for almost 10 years, beginning with the model SD-P40.

These technologies were further advanced by Pioneer in 1993 with the development of the "Cinema Wide" projection monitor line. With a new larger aperture lens, even more of the overscan is brought into focus. This was coupled with a continuously variable expansion circuit to provide the new aspect ratio of 16:10.7.

When factored, the traditional aspect ratio of 4:3 is equivalent to 16:12. Therefore, the new screen dimension of 16:10.7 is relatively wider than conventional NTSC. This new ratio approximates the 16:9 ratio of wide screen TVs (and the forthcoming HDTV) while maintaining the positive attributes of the NTSC standard of filling the screen when reproducing the full image of NTSC material. The continuously variable expansion circuit expands program material in a parabolic fashion. Thus, the degree of expansion is greater at the edges and gradually lessens towards the center where there is no expansion. This works on the premise that most of the action in program material is centered on the screen and is not affected by the circuit. The amount of expansion at the edges has been determined by using a level that would not be perceptible by the viewer, but would yield a pleasing cinematic presentation of NTSC material. The 16:10.7 aspect ratio has been incorporated into the entire Pioneer high resolution projection monitor line. This may not be a purist approach, but we have found that movie enthusiasts particularly appreciate the wide screen look that even standard NTSC material has, plus there is less overscan which provides the viewer with more of the broadcast, VCR, and laserdisc image that is sent to the monitor.

The concept was to put as much of the theater into the home to produce the most advanced and enjoyable home theater experience possible. Pioneer's Cinema Wide high resolution projection monitors do just that.

Albert Margolis
Pioneer Electronics Corporation

© Copyright 1995, 1996, 1997 Secrets of Home Theater & High Fidelity
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