Are resolution specs misleading? What is true resolution requirement for 1080i?

Discussion in 'Beginners, General Questions' started by Lee Shankman, Sep 23, 2004.

  1. Lee Shankman

    Lee Shankman Extra

    Joined:
    Nov 1, 2000
    Messages:
    21
    Likes Received:
    0
    Hello

    I have a question that I've had a hard time answering. I am assuming that 1080i, with its 1080 lines of vertical resolution, implies that there are 1080 pixels of information vertically in a frame (after the interlacing of course). And 480p frames would have 480 pixels of resolution vertically.

    It seems that there are no flat screen displays available that actually have a vertical resolution of 1080 pixels, yet most of them advertise their ability to accept 1080i signals. I understand that these units downsample the signal. But would I not be losing a significant amount of information by doing this? Wouldn't I want to have a display that has 1080 vertical pixels of resolution? I noticed that it can even be difficult to find out the exact resolution of some televisions on their websites -- they emphasize the formats it's capable of displaying but not the true native resolution.

    Thanks...

    Lee
     
  2. ChrisWiggles

    ChrisWiggles Producer

    Joined:
    Aug 19, 2002
    Messages:
    4,791
    Likes Received:
    1
    Yes. There are very few displays that can resolve 1080i, which to resolve technically correctly requires 1080p capabilities.

    I posted an explanation here, which is a little bit of a ramble, but maybe it'll straighten things out a bit for you. IT's a confusing topic because with digital FP displays, the native panel resolution defines what is resolvable.

    With CRTs, there is no native resolution, so it's difficult to describe, and it varies depending on setup.

    Furthermore, there are DLPs out that use a shifting method to approximate more data than is physically available on the chip, so that's another difficult thing to measure that is surfacing in the digital (previously) fixed-pixel world.

    http://www.hometheaterforum.com/htfo...hlight=resolve
     
  3. John S

    John S Producer

    Joined:
    Nov 4, 2003
    Messages:
    5,460
    Likes Received:
    0
    And raw even real resolution numbers don't tell the entire story either, so you can only make it a factor in what ever display model / display technology you end up going with.

    It can be particularly difficult to get any sort of real resolution number for CRT based displays indeed.
     
  4. Jeff Gatie

    Jeff Gatie Lead Actor

    Joined:
    Aug 19, 2002
    Messages:
    6,531
    Likes Received:
    15
    Remember also that just becasue a TV that can display a 1080i signal does not mean that TV has a resolution of 1080 vertical lines/pixels. Displaying a signal does not mean it actually resolves a signal. There are plenty of pocket televisions that can display NTSC signals, but they certainly lack 480 vertical lines of resolution.
     
  5. ChrisWiggles

    ChrisWiggles Producer

    Joined:
    Aug 19, 2002
    Messages:
    4,791
    Likes Received:
    1
    Yes, the issues of input resolutions, displayed resolutions, and resolved resolutions are covered in that linked thread, recommend you read it. If you are focused on one particular display type, you can focus on those explanations, to minimize confusion. But this is a confusing arena, and keep in mind that the final resolvable resolution is just one part of the PQ. There are many other aspects, such as on/off CR, ANSI CR, SDE visibility, rainbow effect, etc that will vary among different displays, and other subjective preferences that are difficult to describe other than with experience. I find this is especially the case with CRT based displays.
     
  6. Lee Shankman

    Lee Shankman Extra

    Joined:
    Nov 1, 2000
    Messages:
    21
    Likes Received:
    0
    Thanks! I'll read the link now. I came up with another interesting question regarding DLPs but I think I'll start a new thread for it.
     

Share This Page