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1080i vs. 720p

Discussion in 'Displays' started by Adam Krogul, Mar 3, 2003.

  1. Adam Krogul

    Adam Krogul Well-Known Member

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    ive been out of the loop for a little while and did a search trying to explain the diferences but came up with no luck. (i didnt look to hard) at anyrate, i wanted to know what displays a better picture and why? my first thought was 1080i but for some reason im second guessing myself... any thoughts would be greatly appreciated.

    l8rz,
    adam
     
  2. Erik_C

    Erik_C Well-Known Member

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    I prefer 1080i. The greatest comparison was between the Super Bowl (720p) and the week's prior playoff games on CBS (1080i). The 1080i had more detail, seemed crisper, and just more realistic. Still, if I'm stuck with 720p, I'm not going to complain. It's excellent.
    -Erik
     
  3. Allan Jayne

    Allan Jayne Well-Known Member

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    1080i gives a more detailed picture of stationary subjects, 720p looks more crisp for moving subjects. For moving objects, very thin details are more likely to want to be reproduced by an odd scan line when the even scan lines are being drawn, or vice versa, we get added flicker or even omission of these small details.

    720p is more sensitive to shortcomings in the electronics, horizontal resolution suffers first. 720p has 1280 pixels all the way across, 1080i has 1920. Both require a "bandwidth" of 37 MHz.

    If the bandwidth of the equipment happens to be half of that required (19 rather than 37 MHz) which is not unusual, the horizontal resolution is halved. 1080i still has about 1000 dots across but 720 has now been cut to 640 dots across (a dot comes out no smaller than 1/640'th the screen width)
     
  4. Adam Krogul

    Adam Krogul Well-Known Member

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    thanks guys... thats what i thought
     
  5. Dean Wette

    Dean Wette Well-Known Member

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  6. RandyMathis

    RandyMathis Well-Known Member

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    Nice article. Thank you!
     
  7. MichaelFusick

    MichaelFusick Well-Known Member

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    http://www.hometheaterforum.com/htfo...hreadid=119696

    Read this thread

     
  8. MichaelFusick

    MichaelFusick Well-Known Member

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    Anyone try the new D-VHS in 720p?

    How does it look?

    Anyone compare it to 1080i?
     
  9. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    Mike, your math is flawed on the 720P calculation. It is always shown one frame at a time. It is always 921,600. Never double.

    1,231,200 form 1080i is still higher based on your reasoning.

    Regards
     
  10. MichaelFusick

    MichaelFusick Well-Known Member

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    I was looking at the "time" of 1 field, not one frame, for which 720p contains more information.

    For 1 frame- 1080i in theory could provide more picture elements, but after the interlaced artifacts- probably won't look as good unless it's a still image.

    Too bad most HDTV is 1080i and most TV's do 1080i and not 720p- which for most ordinary people with TV's makes the whole point a non-issue because their tv supports only one scan rate, and most of the programing is in that scan rate anyways.

    Now for front projection, and D-VHS of HDTV-DVD sources.... I am sure 720p holds many advantages, not only in compression and realstate on disc, but in lack of interlaced and motion artifacts and color.

    Progressive scan typically has better color and contrast I have found... than interlaced.
     
  11. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    What good is 1 field if the eye simply puts two half fields together to form one complete frame of information? It's called temporal resolution ... and its always been that. If you interlace two half fields fast enough ... the eye can't tell anyway.

    It's kinda the same concept as why DVD's are encoded in the 480i format and not 480p.

    Regards
     
  12. MichaelFusick

    MichaelFusick Well-Known Member

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    True- but Progressive scan still promotes or provides better contrast, color, lower noise foor, lower interlaced artifacts, and takes less room on a DVD, Tape, or to broadcast.

    720p is also better for sports, movement, or fast motion.
     
  13. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    Where did you get the idea that progressive scan takes up less space?

    Both formats have their proponents and detractors ... so ultimately ... what is your point? Are you trying to convince us that an orange is better than an apple?

    Regards
     
  14. MikeMcNertney

    MikeMcNertney Well-Known Member

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    Michael, you mention that a single frame of 720p has less information than a single frame of 1080i, even at the reduced horizontal resolution. However, isn't it true that in the same time 1080i shows a single frame (ie, two fields), the 720p shows two full frames (hence the doubling)? So in fact if you are calculating the number of pixels displayed in a certain amount of time the 720p would come out on top (assuming 1080i has a reduced horizontal resolution as mentioned).

    Or are the two 720p frames just duplicates or something?
     
  15. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    The point of interlacing an image is that if you do it fast enough, the eye only sees one complete frame and not a field. This way you can save space since the end result is the same thing. The person sees the same thing. This is why it is called temporal resolution.

    Ideally, we'd all like 1080P ...

    Extra resolution is good if you can see it. If the human eye cannot see it, then the benefit of the extra resolution is lost.

    It's not too different from the DTS / DD arguments that persist ... one uses 12:1 compression and the other ... 3:1 ... though now 6:1 ...

    DD's argument has been that most people cannot hear the difference between music compression rates like these ... so if that is the case, why not save space and use 12:1 instead.

    Ditto for JPEG formats versus TIFF and RAW. If a Fine JPEG compression yields a image virtually indistinguishable from an uncompressed TIFF image, but only takes up 1.5 MB rather than 7 MB ... isn't the JPEG more efficient in terms of space?

    If it's optimal quality with no limitations ... then I want 1080p ...

    Note that I am not anti-720P ... I just want the argument presented properly ...

    Regards
     

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