By Oliver Merk – Principal Consultant
I get asked this question a lot. From clients wishing to display their Flex applications on a wide screen display to friends and family looking to purchase a new LCD television for the livingroom.
The short answer is that it all has to do with resolution.
Video resolution is like sandpaper; the more little grains you pack together, the smoother the surface. It’s the same with your TV screen or computer monitor. The more pixels that can be packed into each inch of the screen, the smoother and clearer images, video and text will appear.
You probably already know that a 1600×1200 computer monitor is subjectively “better” than a 640×480 screen.
Take a typical large sporting venue as an example. You’ve seen jumbo-sized screens attempt to display images and video. In years past, the picture quality was terrible; you could actually see the red, green and blue dots that made up the picture. If you squinted and used your imagination, you could possibly make out the was being displayed, especially if it involved text.
Nowadays, these large screens are a lot better. Why? Because the technology has evolved to allow the pixels (picture elements) to be packed closer together. Therefore, more pixels per inch; therefore higher resolution and image quality.
So what’s this got to do with the big signs at Fred’s Bargain TVs & Food Emporium advertising 1080p televisions?
Well, television screens work the same way as the screens in the large sports arenas. In the old days (the early 1990s), you’d be lucky to get a television to display more than more than a couple of hundred pixels in height.
Why hi-def is so cool
With the introduction of DVDs came the first wave of high definition television screens, which could display 480 pixels vertically. Wow! I remember being blown away at the clarity of these first attempts to improve our viewing pleasure.
But television manufacturers never stand still. A few years later, we were introduced to televisions with 720 pixels vertically. But if DVDs were only 480, why would you need a 720 set? Because the broadcasters were also getting into the game and allowing viewers to receive their shows at 720.
And of course, everything evolved again to where we now have televisions capable of displaying broadcast-quality video at 1080 pixels vertically and 1920 pixels horizontally. Broadcast-quality because the broadcasters now deliver at this resolution.
But what about that p and i thing?
To this point, I haven’t used the infamous “p” or “i” after these vertical pixel counts.
These letters, after the vertical resolution, such as 480i, 720p, 1080i or 1080p, refer to the way the television signal is drawn upon the screen.
Traditional television sets would fill odd-numbered lines of the screen (1, 3, 5, etc.) and then go back to the top and fill in the even-numbered lines (2, 4, 6, etc.). This happened quickly enough to fool your brain into thinking you were seeing smooth motion; around 30 frames per second.
This technique is known as interlacing the signal. The “i” for interlaced in 1080i.
With the advent of faster displays, this trick is no longer necessary; screens can now draw each line onto the screen progressively (1, 2, 3, 4, 5, etc.). So the “p” is for progressive.
The only times you may notice the difference between an interlaced and progressive display is during a fast-moving sporting event or a horizontal pan across a landscape. An interlaced signal will likely appear to stutter, skip or leave short motion trails; a progressive one will look a lot smoother.
At this point, the best display you can get at your typical electronics store is 1080p. But the screen sizes could be 40” and higher. So a 40” 1080p is going to look a lot sharper up close than a larger screen, simply because of how tightly packed the pixels are. The larger screen still look great, especially from a bit farther away.
So if you’re purchasing a new television for the livingroom, you may find that you get a better viewing experience from a 46” than a 72” (although your neighbors won’t be as jealous).
I hope that clears things up a bit. Now go and explain it to your friends and family.
Tags: resolution, Video
