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720i vs. 720p vs. 1080i vs. 1080p

Read “resolution” to get some background.

You are looking to buy a new HDTV and you see designations such as 720i, 720p, 1080i and 1080p. Before I explain what the letters of “i” and “p” mean, it is important that you understand the concept of frames and frames per second (fps).

Have you ever gone to someone’s house and they have shown you pictures from their vacation? And right after that they have shown you few video clips? Well, ultimately all they have shown you really are pictures. Just one set of pictures was moving at faster rate that other set. Care to guess which one?

Every video clip and movie that you see is ultimately bunch of pictures changing from one to next and to next very fast giving you an illusion of “motion picture”.  In TV/movie industry lingo a picture is a frame. Here is where the term “flames a second” comes in. The number of frames per second designated how many frames (pictures) are being seen per one second. TV broadcast, movies and video clips can be shown in as little as 15fps, through 30fps, 60fps and even more. (Read “how many Hz?” article for more info).

Now that you understand what frames are, let’s find out what “i” and “p” stand for. Remember seeing your friend’s vacation photos? The pictures were full, uninterrupted with no lines or gaps in it; just one solid picture. And since TV’s display pictures, you would assume that you see those types of uninterrupted pictures X many times per second. Well, yes and no. The letter “p” stands for “progressive”. In other word you see the entire picture X many times per second every second. That was the yes and now the no. The letter “i” stands for “interlaced” and in other words it means that the picture (frame) that you see X many times per second is put together from 2 pictures (frames).

p for progresive scan

The example above depicts how the images (frames) look as they progress from one frame to another to another. Each image that you see is a nice whole sharp picture with no missing data or colors.

i for interlanced scan

This example however, shows how interlaced images work. As you can see each frame gives you only half of the data while other gives you other half. Together they will give you one frame, but what took progressive only one frame to display, interlaced took two frames thus twice as long; if they both run same frame rate (fps). Why that matters so much, well watch the following video and then I will explain…

video coming soon…

Is there a big difference between 1080p and 720p?

There are more than few TV’s that are offered in both 720p and 1080p standards, in same size.  But can you really see the difference between 1080p and 720p on same size TV?

If the TV you are buying is 32” or smaller you will not see any difference between 720p and 1080p. There is just not enough of picture area to go around for 1080p to do anything special. If however you are considering buying 37” TV or bigger, you might want to go with 1080p as there will be cases where the benefits of 1080p resolution will become noticeable. If you are buying TV that is 50” or bigger it will be a mistake to buy it in 720p as there is too much screen area and not enough picture quality to go around. Benefits of 1080p 50” or larger TV’s will definitely be noticeable.

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