1080p: A visual revolution
By The Vann’s Editorial Team
Last revised October 12th, 2009
HD forces are taking over the television world. And you’re either with the revolution or against it. Or maybe it’s more accurate to say you’re either with the revolution or without it. You definitely want to be “with it.” To be with it, you have to have a television that can accept and display HD signals. You have three options — 720p, 1080i, or 1080p. Though the first wave of HD sets were 720p or 1080i, manufacturers are now responding to consumer demand for 1080p. Why, you might ask, is there demand for 1080p? Read on, comrade, and discover the highest of high definition.
In the hierarchy of high definition digital TV formats, 1080p (p for progressive) has the highest resolution of all with 1920 x 1080 pixels at 30 frames per second. Some manufacturers of fixed-pixel displays like DLP, LCD, and plasma are upgrading their current 720p sets directly to 1080p, skipping the 1080i (i for interlaced) format, since those sets convert interlaced signals to progressive scan before the signals are displayed. Many see 1080p as the unifying widescreen HDTV format, ending the 720p/1080i controversies by combining the progressive scanning of 720p with the resolution of 1080i.
It’s important to note that HD broadcasts are transmitted in either 720p or 1080i resolution, most often 1080i. Let’s do the math. If your television displays 720p, it must convert the 1080i signal into a usable picture for its specifications. A 1080i signal has 1920 vertical lines of pixels and 1080 horizontal lines. Because the signal is interlaced, the picture is actually flashed on the screen in two parts. First, all the odd-numbered horizontal lines of pixels are flashed on screen followed 1/60th of a second later by the even-numbered lines of pixels. Together, the two flashes create the complete image. But a 720p television only has 1280 vertical and 720 horizontal lines of pixels. Somehow, the television has to take the information embedded in a 1080 signal and shrink it to fit a 720 size. To achieve this, the television chooses to combine or eliminate pixels, losing information in the process. A 720p picture does not have as good a resolution as a 1080, so the picture will not be as crisp and detailed. Comparatively, a 1080p television can accept a 1080i signal without losing any of the pixel information, maintaining a sharp, colorful image.
So if HD broadcasts are in 1080i, why not get a television with a native resolution of 1920 x 1080i? There are two reasons. First, progressive scanning gives you a better picture than interlaced scanning. Because the picture is separated into two elements, and there is a time gap between the first flash and the second (no matter how indistinguishable it seems), you may see motion artifacts or flicker on the screen. Think of a horse race, where the horses are in constant motion. Even in 1/60th of a second, they will have changed position, and the difference between the odd-numbered image and the even-numbered image can make the picture appear blurry in the spots with most action. But if all pixels are flashed on the screen at the same time, there’s no opportunity for one half of the picture to lag behind the second half.
Another reason investing in 1080p can pay off is because external video sources are moving that direction. You’ve heard of Blu-ray Disc, right? The new wave of home entertainment is generating so much excitement because it displays video in 1080p format, resulting in the best picture available for your home theater. In order to get the most out of this near-theater experience, you have to have a television that can display a 1080p signal. Trust us when we say that Blu-ray is not going away. Just like DVDs took over for VHS, eventually shelves will be filled with the newest, and best, format, and standard DVDs will eventually be impossible to buy new. Wouldn’t it be nice to have a television that can display movie content in its native resolution?
The question remains whether broadcasters will eventually offer all their programming in 1080p. It is definitely possible and even seems reasonable, though there are no current plans to take this step. When a signal is broadcast, whether it is old standard analog or new digital, it requires a certain amount of space, or bandwidth. This is a term most people associate with computers or the internet. However, bandwidth really describes the capacity of a medium to transmit data. Think of bandwidth as a road — the wider the road the more cars you can fit on it. Digital bandwidth is much wider than analog. Expanding to digital allows broadcasters to send out higher definition signals without causing a traffic jam. The 1080p signal takes the most amount of bandwidth to transmit. As bandwidth is expanded through the changeover to digital broadcasting, there will be more space available to send higher definition signals. Eventually, it may be technologically feasible to broadcast in 1080p.
But there are a couple of caveats to consider with a 1080p television. First, displaying content from external components (such as a Blu-ray player) requires an HDMI (High Definition Multimedia Interface) connection. This type of connection allows both digital video and digital audio information to be transmitted over one cable. Just like 1080p requires a considerable amount of bandwidth, it also requires this special connection. Using component (or other) connectors would result in a downconverted signal, defeating the purpose of 1080p.
Get ready to do a happy dance because we’re about to offer you a valid reason to get a bigger screen. Unlike big screens of old, you can sit closer to a 1080p screen and still see all the glorious details but not be completely overwhelmed by the picture. So go ahead, get a 70” screen for your bedroom. Be aware, though, that if you sit more than two and a half times the width of the screen away from the television, you’ll lose some of the detail offered by 1080p. So if you have a screen that’s 35 inches wide (this is the actual width of the screen, not the “size” of the screen; screen size is measured diagonally), you should sit no further than 87.5 inches, or seven feet, three inches away from the television.
So the moral of the story, fellow revolutionaries, is that a television set with a native 1080p resolution will display the more common 1080i HD signal without compressing or eliminating data, so you’ll have an improved HD picture. This is a step up from downconverting a 1080i signal to work on a 720p television. A 1080p HDTV is also a perfect match for Blu-ray since it utilizes 1080p as its standard. The 1080p HDTV will show Blu-ray materials at the highest resolution possible. And there is the possibility that future television programs will be broadcast in 1080p. Finally, televisions with 1080p native resolution work with today's standards, and afford you the best chance of future compatibility.