Television resolutions are broken down into a number and a letter. Something that a lot of people don’t realize is that 480, the “standard” definition, even has a letter after it. The letter indicates what type of “scan” the television does, or how it draws the image on the screen.
In the lettering system, “I” indicates that it is an interlaced scan. That means, simply, that the screen is drawn one line at a time, starting at the top with line number one and then going to line number 3, then 5, then 7, and so on. Once that is finished, the scan starts at the top again and goes line 2, 4, 6, 8 etc. Obviously, this is done so fast that we can’t see it, and it looks like a steady image.
The “P” indicates a progressive scan. The television starts with the line on the top and draws it, then goes on to line 2, then 3, then 4, then 5, etc…
In tube televisions, this would mean better picture quality because in an interlaced scan the television draws half, then the other half, for a total of 1 frame, every 2 passes. In the U.S., tv’s run at 60 hz, for a total of 60 passes per second, or 30 frames per second. In the U.K. and many other parts of the world, they run at 50hz, for 25 frames per second.
On a progressive scan, though, each pass is a full image so we get 60 frames per second in the U.S. and 50 frames per second in many other parts of the world.
GROOVY!
And let’s talk about those numbers – 480? 720? 1080? Is this a television or Tony Hawk’s trick list?
The number indicates the number of horizontal lines which are to be drawn. 480 = 480 lines, 720 = 720 lines and 1080 means 1080 horizontal lines of picture. Of course if the sets are the same size, you can see that there’s a lot more visual data crammed into the 1080 set than there is into the 480 or the 720. In fact there’s 2.25 times as many lines than the 480 and 1.5 times as many that the 720. That means BETTER. Better picture quality, to be precise. More crisp. Cleaner. More hi-deffer.
Back in the old days, we were all about the 480 I here in the states. We call that “standard definition”. Then someone came up with 480p, which is referred to as “enhanced definition”. From there, some wonderful person came up with 720p and then with 1080p, which are both called “high definition”. Now, we’re playing around with resolutions which are even higher! Up to 4000 horizontal lines of picture.
Wow.
And what’s this 4:3, 5:4, 16:9 crap all about? Simple. That tells us if a resolution is standard or wide-screen. In 4:3 (standard), you have 4 vertical lines of pixels (picture elements) for every 3 horizontal, resulting in a image which is almost square. In 16:9, you have 16 vertical lines of pixels for every 9 horizontal, which results in wide-screen format! For television purposes, those are the only ones we use at this point.
So the next time you go out looking for a TV, you’ll know what you want and you won’t let any pesky sales person tell you differently, right?
RIGHT!
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