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High Definition formats are designed to deliver better quality picture and sound. You have probably noticed that many devices now support variety of new video resolutions and audio decoding standards. In this section of our website we will try to give you a simple explanation of the main differences between the old and new technology. HIGH DEFINITION VIDEO To purchase the most suitable High Definition display you should know how to read the specifications and what to look for. The differences between resolutions are easy to understand and people often make decisions to purchase a display device based primarily on its size and resolution specifications.
You have surely noticed the "i" and "p" letters after the vertical resolution numbers, let us try to explain the difference. In "i"nterlaced format each frame of video is sent in two transmissions. Each transmission in 1080i is composed of 540 rows of pixels running from the top to the bottom of the screen. With the odd rows displayed first and the even rows displayed second, both transmissions create a full frame, made up of all 1080 pixel rows or lines, every 30th of a second. In "p"rogressive format each frame of video is sent in a single transmission. This means that both the odd and even rows (in 1080p all 1080 pixel rows) that make up the full picture are displayed progressively. This often results in a smoother looking image, with less motion artifacts. Nevertheless, if your display has excellent de-interlacing support you will not be able to see any difference between 1080i and 1080p. Please note that display’s native resolution may not be as high as the resolution of the highest format it supports. For example your display may have enough pixels to display 720 format without loss of any details, however, when you try to watch 1080 formats the display will rescale the original picture to fit its smaller native resolution in effect delivering less detailed image. It may be hard to believe but resolution is not the most important aspect of the perceived picture quality. As you already know there are 5 times more pixels in 1080 resolution than in 576 resolution, to illustrate this difference let us compare the two images below. In the first image on the left side each pixel is as large as a single pixel on your screen. In the second image on the right side we have changed the size of pixels to be 5 times larger.
We can hear you saying, the first image looks so much better! Undoubtedly, it does, but we encourage you to get up and walk away from your monitor. As the viewing distance increases you will discover that it is much harder to see the difference between these two images. This simple experiment shows why you need a fairly large screen to experience the benefits of 1080 resolution, to display a sharp and detailed image on a large screen you simply need more pixels. However, putting a lot of pixels on a small screen makes no sense if you are viewing it from a distance. Without high contrast ratio, color saturation and accuracy even the highest resolution display will perform poorly. It is not uncommon to see older generation standard definition plasma screens capable of 10000:1 contrast ratio delivering much better looking picture when compared to a newer LCD panels with significantly lower contrast ratio. We have created two more examples to illustrate the most common problems with high definition displays. The first image on the left side shows low contrast ratio (darker colours look lighter affecting the colour depth). The second image on the right side shows low contrast ratio combined with poor colour saturation and accuracy.
In summary when you are looking for a new high definition display or projector you should look for the following features:
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