Progessive scan

Discussion in 'Playback Devices' started by Andy Stocker, Oct 15, 2003.

  1. Andy Stocker

    Andy Stocker Stunt Coordinator

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    I've been doing a lot of research into the realm of picture resolution and scan rates of TV's (probably not enough!) Now, I've been a computer geek for a long time and I've read alot of discussion about progressive scan and it still confuses me somewhat. Ok, is comparing 480p to 480i like comparing 60 frames per second to 30 frames per second?
    Or am I WAY off base there? I know, I know someone will say "do a search on this discussion and you will find your answer", I'm just trying to find an easy way to explain progressive scan to myself!

    Thanks,

    Andy
     
  2. Sean^M

    Sean^M Stunt Coordinator

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    480i is an interlaced image.
    the guns have to scan the field twice per frame.
    odd lines first, then even lines to complete one full frame.
    480P (progressive) is a non-interlaced, single pass scan of the field. That's the difference between the two.
    a progressive scan should yield a better picture quality, with a good chipset at least. Your ability to pick up the differences is mostly a matter of your eyes, the equipment you have, and knowing what to look for.

    in regards to computers, look at an interlaced JPG compared to a non interlaced JPG as they each load on a slower PC. You'll notice some differences as they load. (lacking a slow PC, try loading one of each, with high res images, on a dialup net connection)

    I'm sure others will give you a better explanation. I'm an engineer. My descriptive skills aren't that polished.
     
  3. Don_Berg

    Don_Berg Supporting Actor

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    480i has 60 interlaced fields/sec (each field is 720x240) while 480p has 60 progressive frames/sec (each frame is 720x480). The horizontal scan rate required for 480p is double that of 480i.
     

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