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Visual "clipping"?

Discussion in 'Electronic Basics' started by Radium, Sep 4, 2007.

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  1. Radium

    Radium Guest

    Hi:

    Clipping in an audio signal results when an audio device receives a
    signal that is too loud. The audio signal distorts into square-waves
    because the "tops" of the signal are flattened. The device cannot
    handle power levels over a certain level. When this level is exceeded,
    clipping occurs. Clipping is usually harsher in digital devices than
    in analog devices. Analog clipping tends to be fuzzy and soft compared
    to digital clipping.

    What is the visual-equivalent of "clipping"? Is there a difference
    between analog and digital in terms of visual-clipping? If so, what is
    the difference?

    Auditory-clipping can damage speakers. Can visual-"clipping" damage
    monitors?


    Thanks,

    Radium
     
  2. isw

    isw Guest

    Clipping causes whites lose all texture -- very similar to overexposed
    film.
    No. Prolonged blacks can damage television transmitters, however (video
    is inverted for transmission, so black requires full power from the
    transmitter).

    Isaac
     
  3. Radium

    Radium Guest

     
  4. Prolonged bright areas (whether clipped or not) will damage CRT
    monitors. I have two on the bench right now to have their CRTs
    replaced because the image is burned-in. They came from a
    security/survelience application and you can somewhat see the
    hallway and the doors they were monitoring.
     
  5. Matt Ion

    Matt Ion Guest

     
  6. Matt Ion

    Matt Ion Guest

    ANY static image for a prolonged time will cause burn-in on a CRT or
    plasma display. The brighter it is, the less time it takes, but it
    doesn't have to be pure white for burn to occur. Simply displaying 100%
    white won't cause instant death of a monitor, however, the way a clipped
    signal can damage a speaker.
     
  7. Radium

    Radium Guest

    Can damage occur to a CRT/Plasma/LCD monitor from an area that is
    extremely-bright for an extremely short time? Let's say one attempts
    to force 2400 lumens of light-intensity out of an area of the monitor
    for around 5 seconds. What damage would affect that region of the
    screen?

    Warning! Crazy scenarios are presented below. None-the-less I still
    find them interesting:

    Try to force 100,000,000 lumens out of a square-shaped, pinky-finger-
    sized area of an LCD monitor. Now what would happen? Would the organic
    material present in that area catch fire?

    For an acoustic-analogy, let's say one tries to force a 400,000 Hz,
    144 dB sine-wave tone out of a Bose loudspeaker. The result: a very
    expensive fire. The plastics/paper in the speaker would likely ignite.
     
  8. Matt Ion

    Matt Ion Guest

    Ummm, probably none, as the output would be limited by the drive systems
    of the display. The only thing you could "force" into it would be a
    high-voltage video signal, which would fry the input circuitry, but
    probably not a lot else.

    To extend the analogy to audio, your speaker would have its own built-in
    amp with limited output power; you can't "force" it to output more power
    into the speaker.
    And how exactly would one do that, since LCDs don't actually produce
    light on their own?
     
  9. Ron N.

    Ron N. Guest

    If you can find an old analog TV or monitor, just turn up the contrast
    control way too high. All the greys darker than a certain level
    become black, all the greys lighter than a certain level become
    white. Information is lost.
     
  10. Usually he only reads half. Get used to the phenomenon "Radium".

    -m-
     
  11. White clipping makes you loose the texture, and some other interesting
    things occur, like the clipped area turning yellowish (solarization).
    But it's not only white which can clip, with colour-correction you can
    easily clip one of the three colour-channels. And of course you can clip
    black as well, loosing shadow detail.
    I would say the transmitters would be resistant to that. Most run below
    their designed maximum power anyway.

    cheers

    -martin-
     
  12. isw

    isw Guest

     
  13. Paul Mitchum

    Paul Mitchum Guest

    [..]
    Google is your friend.
     
  14. Matt Ion

    Matt Ion Guest

    Guess it's more of a THEORETICAL damage :)

    I think the point is, the way they work, it's POSSIBLE, if unlikely.
     
  15. Yes of course :) They would switch off with all the protections in place.
    But it must have happened at one stage, otherwise it wouldn't be known.

    -m-
     
  16. Battleax

    Battleax Guest

    Radium seems to be a good example of mental clipping. Brain attempting to
    think far beyond it's capacity
     
  17. Radium wrote:

    (snip)
    Clipping results from the saturation of the system, analog or digital.
    That should be true for audio or video.
    In general, audio clipping does not damage speakers. The usual
    case that causes damage is the combination of a few things:

    Using multiple drivers to cover a large frequency range, with
    a crossover network to divide up the signal.

    Musical audio has much more power at lower frequencies than higher
    frequencies, so speakers are designed appropriately.

    Clipping generates a lot of power at the higher harmonics of the
    input frequencies that goes to drivers not designed for
    those power levels.

    In most video systems this combination doesn't exist. It might
    in future video reproduction systems, though.

    -- glen
     
  18. ASAAR

    ASAAR Guest

    You and I couldn't, but an engineer/technician working for a
    company such as GE, Westinghouse, Philips or Osram might go mad and
    try something like that. If we suffered that same fate we might try
    applying 240V A.C. to a 2.6v PR2 bulb to see "what would happen". :)
     
  19. Yes, there IS a difference between analog and digital processing. The
    analog effect depends on the stability of the analog signal
    processing. This effect would appear on the horizontal trace of a TV
    signal (part of the video path on today's TVs are still analog, even
    with a "digital tuner". It can cause a ringing after the saturation,
    and "artifacts" beyond the clipped area.

    If certain types of processing are used, especially sharpening, in
    digital signal processing, such artifacts can also end up surrounding
    (in both directions) a clipped area.
     
  20. Don Bowey

    Don Bowey Guest

    snip

    More Trolling.

    Exactly where did he say prolonged black can damage a monitor/screen
     
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