How can 60 frames per second be displayed with 25ms pixel ..

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

Video gurus,

I need your comments on the following:

While shoppoing for LCD TV, I saw the specs:

1. 25ms pixel response time - means (1000/25 = 40) - a
pixel can be switched on/off 40 times per second?

2. 1280x720p at 60 frames - means 60 frames per second
(progressive)

Where does extra (60 - 40 = 20 ) 20 times switching of the pixel
come from?

I appreciate your comments .... please enlighten me.
4 answers Last reply
More about frames displayed 25ms pixel
  1. Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

    reader wrote:
    > Video gurus,
    >
    > I need your comments on the following:
    >
    > While shoppoing for LCD TV, I saw the specs:
    >
    > 1. 25ms pixel response time - means (1000/25 = 40) - a
    > pixel can be switched on/off 40 times per second?
    >
    > 2. 1280x720p at 60 frames - means 60 frames per second
    > (progressive)
    >
    > Where does extra (60 - 40 = 20 ) 20 times switching of the pixel
    > come from?
    >
    > I appreciate your comments .... please enlighten me.

    It doesn't : and is why you can get tearing. Google for more.
  2. Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

    "reader" <medusamouth@yahoo.com> wrote in message
    news:92d3f983.0411171914.201135fc@posting.google.com...
    > Video gurus,
    >
    > I need your comments on the following:
    >
    > While shoppoing for LCD TV, I saw the specs:
    >
    > 1. 25ms pixel response time - means (1000/25 = 40) - a
    > pixel can be switched on/off 40 times per second?
    >
    > 2. 1280x720p at 60 frames - means 60 frames per second
    > (progressive)
    >
    > Where does extra (60 - 40 = 20 ) 20 times switching of the pixel
    > come from?
    >
    > I appreciate your comments .... please enlighten me.
  3. Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

    "reader" <medusamouth@yahoo.com> wrote in message
    news:92d3f983.0411171914.201135fc@posting.google.com...
    > Video gurus,
    >
    > I need your comments on the following:
    >
    > While shoppoing for LCD TV, I saw the specs:
    >
    > 1. 25ms pixel response time - means (1000/25 = 40) - a
    > pixel can be switched on/off 40 times per second?

    No, not really. It depends on just what definition of
    "response time" is being used. Very often, the quoted
    response time spec is actually the sum of the turn-on and
    turn-off times. It also, in any case, may be the time required
    to turn from full-on to full-off, which can be considerably
    different from the time required to transition between
    intermediate "gray levels." (That time might be shorter, or
    it might be longer - considerably longer! - that the full
    white/black transition time.) And most LC technologies
    require a longer transition time in one direction that the other.
    So the bottom line is that these specs, at least as published
    in a good deal of the information/advertising aimed at the
    end user, may be difficult to compare or to translate
    directly into frame-rate capability.

    >
    > 2. 1280x720p at 60 frames - means 60 frames per second
    > (progressive)

    Right.

    >
    > Where does extra (60 - 40 = 20 ) 20 times switching of the pixel
    > come from?

    Nowhere, and in fact a good number of panels spec'ed at
    "25 ms" response times will show smearing or other artifacts
    when operated at these rates with rapidly moving imagery.
    However, note that the response time does NOT restrict the
    rate at which new frames can be written into the panel. Most
    LCDs these days are run at at LEAST a 60 FPS rate; whether
    or not moving objects appear as you'd like them to is another
    matter altogether.

    Look at it this way - let's say I can throw baseballs to you
    at the rate of one per second, and you can catch them that
    fast. That doesn't mean, though, that you'll have time to
    read the labels on each one.

    Bob M.
  4. Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

    "Bob Myers" <nospamplease@address.invalid> wrote in message
    news:lIdnd.3199$bP4.1795@news.cpqcorp.net...
    >
    > "reader" <medusamouth@yahoo.com> wrote in message
    > news:92d3f983.0411171914.201135fc@posting.google.com...
    > > Video gurus,
    > >
    > > I need your comments on the following:
    > >
    > > While shoppoing for LCD TV, I saw the specs:
    > >
    > > 1. 25ms pixel response time - means (1000/25 = 40) - a
    > > pixel can be switched on/off 40 times per second?
    >
    > No, not really. It depends on just what definition of
    > "response time" is being used. Very often, the quoted
    > response time spec is actually the sum of the turn-on and
    > turn-off times. It also, in any case, may be the time required
    > to turn from full-on to full-off, which can be considerably
    > different from the time required to transition between
    > intermediate "gray levels." (That time might be shorter, or
    > it might be longer - considerably longer! - that the full
    > white/black transition time.) And most LC technologies
    > require a longer transition time in one direction that the other.
    > So the bottom line is that these specs, at least as published
    > in a good deal of the information/advertising aimed at the
    > end user, may be difficult to compare or to translate
    > directly into frame-rate capability.
    >
    > >
    > > 2. 1280x720p at 60 frames - means 60 frames per second
    > > (progressive)
    >
    > Right.
    >
    > >
    > > Where does extra (60 - 40 = 20 ) 20 times switching of the pixel
    > > come from?
    >
    > Nowhere, and in fact a good number of panels spec'ed at
    > "25 ms" response times will show smearing or other artifacts
    > when operated at these rates with rapidly moving imagery.
    > However, note that the response time does NOT restrict the
    > rate at which new frames can be written into the panel. Most
    > LCDs these days are run at at LEAST a 60 FPS rate; whether
    > or not moving objects appear as you'd like them to is another
    > matter altogether.
    >
    > Look at it this way - let's say I can throw baseballs to you
    > at the rate of one per second, and you can catch them that
    > fast. That doesn't mean, though, that you'll have time to
    > read the labels on each one.
    >
    > Bob M.
    >
    Here is an analogy I like better, FWIW
    Your car suspension has a parallel connection of spring
    and "damper" (shock absorber) at every wheel (typically).
    If I take an assembly of that combination and test it on
    an impact machine, I discover that it takes about 100 mS
    (not a real #) for it to go from full compression to full extension.
    I can hit that combination with a "hammer" every 100 mS and
    it will transition the full range of extension.
    But if I hit it more frequently (higher frequency = less time
    between hits), say every 80 mS, then it will not have reached its
    full extension before I hit it again.
    In that condition, I may actually measure the amplitude of
    the motion and say it is (X)% of "full scale". The assembly
    still works, but does not reach "full performance".
    In a LCD display (or any type) that has a response time
    (the time it takes to do a full transition) slower than the refresh
    time (the TIME between each "impact"), the result is less than
    full amplitude "intensity". It is necessary in this case to think
    about time, instead of frequency.

    Help?

    NGA
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