720p vs. 1080i

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I have heard people giving reasons left and right why they should have things equiped at 1080i or 720p. I want to give a simple breakdown whats good for what. The main assumption when viewing either format is that your screen has a ratio of 16:9 which is optimal for either resoltuion. This is less of techinical breakdown and more for practical usage.

720P:
It has 720 lines progressivly scanned to the frame, so you see a total of 720 lines from the picture in front of you. Most sports broadcasts which are in HD are set at 720P because it shows fast moving motion very clearly. So for sports events, games, and high paced action games your better off at setting your machine to output at 720P.

1080i:
It is 1080 lines interlaced to produce a very beautiful image. The slight issue with 1080i is that HDTV sets must de-interlace the input to put it to screen. It all depends how well your screen can handle that process to produce the right image. For slow movies, and images 1080i is superior to 720P, but it may not be the best choice for movies with too much motion.

Now that 1080P is slowly becoming standard on the new LCD and Plasma screens all you have to make sure is that your DVD player and other electronic products output at that level. Even for DVDs which aren’t outputing at 1080P the screen resolution will look better overall.

Link: 720P Wikipedia
Link: 1080i Wikipedia

A guy who is just trying to enjoy life!

5 Comments

  1. Gregory Solman

    Since 720p is effectively 1440i, how can 1080i make a superior picture for movies? Wouldn’t the apparent resolution and color rendition be better in 720p (just as 480p is infinitely superior to 480i for watching SD or upconverted DVDs)?

  2. Juan Gamboa

    Greg,

    1080i means that a total of 1080 lines are drawn to per frame, but the frame is split into two passes on the screen: 540 odd and then 540 even for a total of 1080 lines. On 720p there 720 lines drawn, progessively on each pass, 2 passes to make one frame, so there is not a total of 1440 lines. The interlace or progressive is key to looking at the problem. For example 480i and 480p are exactly the same resolution, but in “i”mode the 480 are split to 240 lines in each pass, 2 to make a frame, and in “p” 480 lines in each pass, and still 2 to make a frame. More lines drawn in each pass making the picture clearer.

  3. Matt

    I’m trying to figure out how the de-interlacing process works for 1080i.

    The way I understand it, in a 480i signal (NTSC over the air TV for instance), the interlaced fields don’t exactly line up perfectly to produce one frame. Each field is shifted in time slightly so that the motion of the subject in the image would cause each successive field to move slightly. Each field is half the full 480 lines, but the frame rate effectively stays high.

    Does a 1080i signal simply take a single 1080p frame and send it in two fields? If so, the de-interlacing process would simply be to combine the two into a 1080p image at half the frame rate.

    Or, does 1080i shift each field in time the same way that 480i did? If this is the case, the de-interlacing process is much more involved. Each de-interlaced frame would contain motion tearing that would also have to be smoothed out somehow.

    -M

  4. Gadget

    Enough of the confusion..Any HD signal that is PROGRESSIVE SCAN is superior then “I” or interlaced..720P is far and away better then 1080I…

  5. Matt

    If only it were that simple.

    I have done a significant amount of research since my previous comment.

    The type of content, and the format in which the content was originally recorded play a huge roll in determining which format is superior.

    720p is superior for sports and other fast motion video because of it’s higher frame rate. 1080i (depending on the situation) can produce a better picture than 720p when displaying images that do not require high frame rates.

    There is no question that progressive is superior to interlaced when comparing the two at the same resolution (1080i vs 1080p), but to say categorically that 720p is always superior to 1080i? That’s simply not true.

    Truth will end the confusion, not broad generalizations.

    -M

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