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Visual "clipping"?

R

Radium

Jan 1, 1970
0
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
 
I

isw

Jan 1, 1970
0
Radium said:
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?

Clipping causes whites lose all texture -- very similar to overexposed
film.
Auditory-clipping can damage speakers. Can visual-"clipping" damage
monitors?

No. Prolonged blacks can damage television transmitters, however (video
is inverted for transmission, so black requires full power from the
transmitter).

Isaac
 
R

Radium

Jan 1, 1970
0
Clipping causes whites lose all texture -- very similar to overexposed
film.

What does this look like on a screen?
No. Prolonged blacks can damage television transmitters, however (video
is inverted for transmission, so black requires full power from the
transmitter).

Prolonged black can damage a monitor/screen? That's weird. White is
analogous to the loudest sound a loudspeaker can playback. Black is
analogous to a loudspeaker not being feed any signal.

When the power-supply of the monitor/screen is turned off, the monitor/
screen is black because it not receiving any voltage.

I would think that extremely-bright white would damage the screen
because the brightest white results from the highest voltage applied
to the Reds, Greens, and Blues [equal intensities of R, G, & B -- if
combined -- appear white to our eyes when emitted by an electronic
monitor] in a particular area of the monitor/screen. If the voltage
exceeds this for prolonged periods of time, that region of the screen
will burn out, much like forcing an extremely-high voltage audio
signal into a speaker will cause the speaker to short-circuit and the
diaphragm to pop and/or melt. Many instructions manual for speakers
give direction not to reach or go above the clipping point and
clipping damages the speakers. Wouldn't something similar happen to a
monitor/screen [whether it's a CRT, plasma, or LCD] if it was forced
to display light-intensities beyond its limits?
 
R

Richard Crowley

Jan 1, 1970
0
No. Prolonged blacks can damage television transmitters, however (video
is inverted for transmission, so black requires full power from the
transmitter).

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.
 
M

Matt Ion

Jan 1, 1970
0
Radium said:
What does this look like on a screen?

An area of just plain white.
Prolonged black can damage a monitor/screen? That's weird.

TRANSMITTERS. HE SAID TRANSMITTERS.
White is
analogous to the loudest sound a loudspeaker can playback. Black is
analogous to a loudspeaker not being feed any signal.

NOT ON A TRANSMITTER. Yeesh. Did you actually read that paragraph AT
ALL???
 
M

Matt Ion

Jan 1, 1970
0
Richard said:
...

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.

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.
 
R

Radium

Jan 1, 1970
0
Prolonged bright areas (whether clipped or not) will damage CRT
monitors.

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.
 
M

Matt Ion

Jan 1, 1970
0
Radium said:
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?

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.
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?

And how exactly would one do that, since LCDs don't actually produce
light on their own?
 
R

Ron N.

Jan 1, 1970
0
What does this look like on a screen?

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.
 
M

Martin Heffels

Jan 1, 1970
0
NOT ON A TRANSMITTER. Yeesh. Did you actually read that paragraph AT
ALL???

Usually he only reads half. Get used to the phenomenon "Radium".

-m-
 
M

Martin Heffels

Jan 1, 1970
0
Clipping causes whites lose all texture -- very similar to overexposed
film.

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.
No. Prolonged blacks can damage television transmitters, however (video
is inverted for transmission, so black requires full power from the
transmitter).

I would say the transmitters would be resistant to that. Most run below
their designed maximum power anyway.

cheers

-martin-
 
I

isw

Jan 1, 1970
0
Radium said:
What does this look like on a screen?

Just as I said: white areas with no texture.
Prolonged black can damage a monitor/screen? That's weird. White is
analogous to the loudest sound a loudspeaker can playback. Black is
analogous to a loudspeaker not being feed any signal.

I did not say "monitor"; I said "transmitter". There *is* a difference.
When the power-supply of the monitor/screen is turned off, the monitor/
screen is black because it not receiving any voltage.

It's not voltage; it's current, that determines brightness during the
normal operation of a monitor.
I would think that extremely-bright white would damage the screen
because the brightest white results from the highest voltage applied
to the Reds, Greens, and Blues [equal intensities of R, G, & B -- if
combined -- appear white to our eyes when emitted by an electronic
monitor] in a particular area of the monitor/screen.

Actually it's not voltage; it's current.

And it takes a long time for overdriving to cause damage to an ordinary
monitor.
Wouldn't something similar happen to a
monitor/screen [whether it's a CRT, plasma, or LCD] if it was forced
to display light-intensities beyond its limits?

CRT's possibly, over a long period of time. LCDs, never. The LCD part is
just a bunch of "valves"; the light source is usually a fluorescent lamp
of some sort. No possibility of "burning anything out".

I have been involved with very special CRT-based imaging devices where
an uncontrolled momentary pulse would destroy the phosphor -- and in
fact, *drill a pit in the glass of the faceplate*. But that is unlikely
to ever happen to a CRT used as a video monitor.

Isaac
 
P

Paul Mitchum

Jan 1, 1970
0
[..]
What is the visual-equivalent of "clipping"?
Blowouts.

Is there a difference between analog and digital in terms of
visual-clipping?
Yup.

If so, what is the difference?

Google is your friend.
 
M

Matt Ion

Jan 1, 1970
0
Martin said:
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.

Guess it's more of a THEORETICAL damage :)

I think the point is, the way they work, it's POSSIBLE, if unlikely.
 
M

Martin Heffels

Jan 1, 1970
0
I think the point is, the way they work, it's POSSIBLE, if unlikely.

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-
 
B

Battleax

Jan 1, 1970
0
Radium seems to be a good example of mental clipping. Brain attempting to
think far beyond it's capacity
 
G

glen herrmannsfeldt

Jan 1, 1970
0
Radium wrote:

(snip)
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?

Clipping results from the saturation of the system, analog or digital.
That should be true for audio or video.
Auditory-clipping can damage speakers. Can visual-"clipping" damage
monitors?

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
 
A

ASAAR

Jan 1, 1970
0
And how exactly would one do that, since LCDs don't actually produce
light on their own?

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". :)
 
D

Don Stauffer in Minnesota

Jan 1, 1970
0
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

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.
 
D

Don Bowey

Jan 1, 1970
0
snip

Prolonged black can damage a monitor/screen? That's weird. White is
analogous to the loudest sound a loudspeaker can playback. Black is
analogous to a loudspeaker not being feed any signal.

snip

More Trolling.

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