I am considering the purchase of an LED television. However, before I do, I
would like to know what the difference is between 120 & 240hz; other than
the numbers. I've done some research, but there seems to be a wide array of
conflicting opinions. I know that it has to do with refresh rate, jitter,
and blur. So, if anyone has some straightforward input on the matter, I'm
all (grateful) ears.

Thanks

On 26/02/2010 9:51 AM, Chris wrote:
I am considering the purchase of an LED television. However, before I
do, I would like to know what the difference is between 120 & 240hz;
other than the numbers. I've done some research, but there seems to be a
wide array of conflicting opinions. I know that it has to do with
refresh rate, jitter, and blur. So, if anyone has some straightforward
input on the matter, I'm all (grateful) ears.

Thanks

An alien with 240Hz eyes might appreciate[*] the higher frequency
version, but unless you're such an alien living on Earth incognito,
don't waste your money.

Sylvia.
[*] Ignoring the fact that colour displays are finely tuned to the way
that human colour vision works, and an alien would likely wonder what
we'd been smoking.

First, the only televisions that use LEDs use OLEDs. There are none using
conventional LEDs.

Second, there are no strict definitions of what these refresh rates mean. In
some cases, the set generates an interpolated image at that rate, in others,
a blank (black) raster is inserted. Some sets combine both.

I don't like this enhancement (which was one of the reasons I bought a
plasma set). It has a nasty side-effect -- it makes motion pictures look
like video. This might be fine for a TV show; it isn't when you're watching
movies. Be sure that whatever set you purchase has some way of defeating it
the enhancement.

You need to actually look at the sets you're considering with program
material you're familiar with.

Ignoring the fact that colour displays are finely tuned
to the way that human colour vision works, and an alien
would likely wonder what we'd been smoking.

This has nothing whatever to do with color rendition.

Who is Sylvia, anyway?

On 25/02/2010 23:46, William Sommerwerck wrote:
First, the only televisions that use LEDs use OLEDs. There are none using
conventional LEDs.

none ??

--
Adrian C

First, the only televisions that use LEDs use OLEDs.
There is none using conventional LEDs.

None ??

Nope. The only sets available use LCDs, plasma, and OLEDs.

"William Sommer****** IDIOT "
"Sylvia Else"

Ignoring the fact that colour displays are finely tuned
to the way that human colour vision works, and an alien
would likely wonder what we'd been smoking.

This has nothing whatever to do with color rendition.


** And if you put the remark back into its context - what it IS relevant
to becomes obvious.;

****WIT !!



... Phil




Who is Sylvia, anyway?

On Fri, 26 Feb 2010 00:07:43 +0000, Adrian C wrote:
On 25/02/2010 23:46, William Sommerwerck wrote:
First, the only televisions that use LEDs use OLEDs. There are none using
conventional LEDs.

none ??

I think when they refer to LEDs, it is LEDs used for backlighting
probably for an LCD.

"William Sommer****** IDIOT "

First, the only televisions that use LEDs use OLEDs. There are none using
conventional LEDs.


** Fraid " LED TVs " are on sale all over the world right now.

****WIT !!

http://en.wikipedia.org/wiki/LED-backlit_LCD_television



..... Phil

On 26/02/2010 10:47 AM, William Sommerwerck wrote:
Ignoring the fact that colour displays are finely tuned
to the way that human colour vision works, and an alien
would likely wonder what we'd been smoking.

This has nothing whatever to do with color rendition.

Did I say it had? I was attaching a caveat to the word "appreciate".

Who is Sylvia, anyway?


Sylvia is Sylvia Else.

Sylvia (Else).

"Phil Allison" wrote in message
...

"William Sommer****** IDIOT "

First, the only televisions that use LEDs use OLEDs. There are none using
conventional LEDs.


** Fraid " LED TVs " are on sale all over the world right now.

****WIT !!

http://en.wikipedia.org/wiki/LED-backlit_LCD_television



.... Phil



Your Wiki reference says it all. These are NOT LED televisions, as we
discussed on here a few weeks back, no matter what misleading crap the
manufacturers use to try to convince dumb punters otherwise. These so-called
LED TVs are conventional LCD sets, with all the drawbacks of that
technology, but backlit with LEDs instead of CCFLs.

Arfa

"William Sommerwerck" wrote in message
...
First, the only televisions that use LEDs use OLEDs. There are none using
conventional LEDs.

Second, there are no strict definitions of what these refresh rates mean.
In
some cases, the set generates an interpolated image at that rate, in
others,
a blank (black) raster is inserted. Some sets combine both.

I don't like this enhancement (which was one of the reasons I bought a
plasma set). It has a nasty side-effect -- it makes motion pictures look
like video. This might be fine for a TV show; it isn't when you're
watching
movies. Be sure that whatever set you purchase has some way of defeating
it
the enhancement.

You need to actually look at the sets you're considering with program
material you're familiar with.



Seconded on all counts, and also the reason that I recently bought a plasma
TV (Panasonic, 50" full HD panel, 400Hz). I have not seen a single thing
about this TV that I don't like so far, unlike the LCD TVs that I have in
the house, and the LCDs that cross my bench for repair, all of which suffer
from motion artifacts, scaling artifacts, and motion blur ...

This plasma TV has produced absolutely stunning HD pictures from the Winter
Olymics, with not the slightest sign of motion artifacts of any description,
even on the fastest content like downhill skiing, and bobsleigh etc. In
contrast, the same content that I have seen on LCDs, has been perfectly
dreadful.

Arfa

"Arfa Daily"
"Phil Allison"
"William Sommer****** IDIOT "

First, the only televisions that use LEDs use OLEDs. There are none
using
conventional LEDs.


** Fraid " LED TVs " are on sale all over the world right now.

****WIT !!

http://en.wikipedia.org/wiki/LED-backlit_LCD_television



Your Wiki reference says it all. These are NOT LED televisions,

** But they are called " LED TVs " by their makers and so are

*KNOWN BY THAT NAME* to members of the public.


Fools like YOU and Sommer****** would complain that a bottle of "Steak
Sauce" contained no steak.



..... Phil

Fools like YOU and Sommer****** would complain
that a bottle of "Steak Sauce" contained no steak.

And, as we all know, Girl Scout Cookies are not made from Girl Scouts.

On 2/25/2010 5:55 PM Sylvia Else spake thus:

On 26/02/2010 10:47 AM, William Sommerwerck wrote:

Ignoring the fact that colour displays are finely tuned
to the way that human colour vision works, and an alien
would likely wonder what we'd been smoking.

This has nothing whatever to do with color rendition.

Did I say it had? I was attaching a caveat to the word "appreciate".

Who is Sylvia, anyway?

Sylvia is Sylvia Else.

Sylvia (Else).

Since the subject's been broached, may I ask: are you a woman? I ask
because, well, 99.9% of the other posters here aren't, and it's unusual
to see a woman posting in such a newsgroup (actually pretty much on
Usenet in general, a few newsgroups excepted).

None of my business, I know, but I'm curious.


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

On 26/02/2010 3:31 PM, David Nebenzahl wrote:
On 2/25/2010 5:55 PM Sylvia Else spake thus:

On 26/02/2010 10:47 AM, William Sommerwerck wrote:

Ignoring the fact that colour displays are finely tuned
to the way that human colour vision works, and an alien
would likely wonder what we'd been smoking.

This has nothing whatever to do with color rendition.

Did I say it had? I was attaching a caveat to the word "appreciate".

Who is Sylvia, anyway?

Sylvia is Sylvia Else.

Sylvia (Else).

Since the subject's been broached, may I ask: are you a woman? I ask
because, well, 99.9% of the other posters here aren't, and it's unusual
to see a woman posting in such a newsgroup (actually pretty much on
Usenet in general, a few newsgroups excepted).

None of my business, I know, but I'm curious.



Yes, I am.

Sylvia.

Sylvia Else wrote in message
...
On 26/02/2010 9:51 AM, Chris wrote:
I am considering the purchase of an LED television. However, before I
do, I would like to know what the difference is between 120 & 240hz;
other than the numbers. I've done some research, but there seems to be a
wide array of conflicting opinions. I know that it has to do with
refresh rate, jitter, and blur. So, if anyone has some straightforward
input on the matter, I'm all (grateful) ears.

Thanks

An alien with 240Hz eyes might appreciate[*] the higher frequency
version, but unless you're such an alien living on Earth incognito,
don't waste your money.

Sylvia.

[*] Ignoring the fact that colour displays are finely tuned to the way
that human colour vision works, and an alien would likely wonder what
we'd been smoking.


Ah that explains why I cannot watch these things for more than a few
minutes, I'm an alien. Would anyone know what the equivalent refresh rate is
for good old CRT technology ? As far as fast movement across the image is
concerned, motion jitter or judder or whatever the term is. What refresh
rate would have to be there before I cannot tell the difference between that
part of the technologies?

"Phil Allison" wrote in message
...

"Arfa Daily"
"Phil Allison"
"William Sommer****** IDIOT "

First, the only televisions that use LEDs use OLEDs. There are none
using
conventional LEDs.


** Fraid " LED TVs " are on sale all over the world right now.

****WIT !!

http://en.wikipedia.org/wiki/LED-backlit_LCD_television



Your Wiki reference says it all. These are NOT LED televisions,

** But they are called " LED TVs " by their makers and so are

*KNOWN BY THAT NAME* to members of the public.


And it's time something was done about that. The manufacturers are
relentlessly plugging this as though it's some new and wonderful display
technology, and it's not (although I have to say that the TV ad campaign
that was running here seems to have stopped now). It is misleading nonsense,
and although all civilised countries have laws against misleading
advertising, for some reason, they seem to be letting this one go,
presumably because like you, they don't have any understanding of what is
actually *meant* by the term, rather than *implied* by it.

By the way the OP was talking, he doesn't understand either, and is in the
process of *being* misled by it and, since he asked, it is up to those of us
who *do* understand, to help him out with his question, and stop him
potentially wasting his hard-earned on something that is not exactly what he
thought it was.

Now if you have anything sensible and informative to say on the issue, go
right ahead Philip. Otherwise, if it's just more of your normal anger and
abuse that's festering ready for you to unleash, go have a beer or whatever
instead, and chill ...

Arfa




Fools like YOU and Sommer****** would complain that a bottle of "Steak
Sauce" contained no steak.



.... Phil

In article ,
Phil Allison wrote:
Your Wiki reference says it all. These are NOT LED televisions,

** But they are called " LED TVs " by their makers and so are

*KNOWN BY THAT NAME* to members of the public.

Wonder what name they'll invent for proper LED TVs when they arrive?

And why aren't all LCD sets known by the name of the backlight?

--
*Some people are only alive because it is illegal to kill.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Arfa Daily wrote:
Now if you have anything sensible and informative to say on the issue,
go right ahead Philip. Otherwise, if it's just more of your normal
anger and abuse that's festering ready for you to unleash, go have a
beer or whatever instead, and chill ...

If he's like this sober, imagine what he'd be like drunk...

--
*If you don't pay your exorcist you can get repossessed*

Dave Plowman London SW
To e-mail, change noise into sound.

On 26/02/2010 01:14, AZ Nomad wrote:
On Fri, 26 Feb 2010 00:07:43 +0000, Adrian wrote:
On 25/02/2010 23:46, William Sommerwerck wrote:
First, the only televisions that use LEDs use OLEDs. There are none using
conventional LEDs.

none ??

I think when they refer to LEDs, it is LEDs used for backlighting
probably for an LCD.

Yup :-)

Don't know in the US, but over here when folks speak of an LED
television, it's now accepted it's an LCD with a LED backlight.

Besides I've read that Sony have dropped their plans to go to large
scale manufacture with OLED for the moment.

--
Adrian C

"Dave Plowman (News)" wrote in message
...
In article ,
Phil Allison wrote:
Your Wiki reference says it all. These are NOT LED televisions,

** But they are called " LED TVs " by their makers and so are

*KNOWN BY THAT NAME* to members of the public.

Wonder what name they'll invent for proper LED TVs when they arrive?

And why aren't all LCD sets known by the name of the backlight?

--
*Some people are only alive because it is illegal to kill.

Dave Plowman London SW
To e-mail, change noise into sound.


Yes, quite.

To the OP

If you are seriously considering the purchase of a flatscreen TV of any
description, the best advice I can give you is to know what you're asking
and seeing in the showroom. Setting aside technical sales mumbo jumbo about
refresh rates and so on, you need to understand what you're looking at.
There are two basic competing technologies - LCD and plasma. LCD are in
general cheaper, but the panel has a slower reponse, which tends to lead to
motion blur, so if you are into sports, then you need to see any TVs that
you are interested in, displaying this sort of content. Plasma TVs suffer
little or no motion blur due to the extremely high switching speed
capability of the individual plasma cells in the screen. Plasma panels also
do not suffer from any viewing angle issues, which can be a problem with
LCDs, particularly if you are thinking of wall-mounting, as most will then
need to be angled down towards your sitting position.

You should also be aware that there are several 'resolutions' of screen and
drive to take into consideration. Almost all TV showrooms both here and in
the US, tend to have the sets running on at least an HD picture, and often a
BluRay picture. This makes them look very good at first glance. Problem is
that in normal day to day use when you get it back home, you are going to be
watching standard resolution terrestrial broadcasts on it, and on many sets,
these look pretty dreadful, and it is the reason that so many people are
disappointed with their purchase when they get it home, and think that it is
not what they saw in the store.

The reason for this is that the actual display panel has a 'native
resolution', which is likely to be at least broadcast HD. When you then
apply a standard resolution signal to the TV, this has to be 'scaled up' to
match its low resolution to the panel's high resolution. This often results
in scaling artifacts which may well be much more noticeable as motion
artifacts, with fast moving (and sometimes not-so-fast) objects on the
screen.

BluRay is a full HD source. This is handled fine by most sets, but be aware
that if the TV is just HD compatible rather than "Full HD", then the native
resolution of the actual display panel, will again not match the resolution
of the signal, and downscaling will take place within the TV to make them
match.

So, if you are a film buff, and likely to watch stuff on BluRay, you should
consider a set with a full HD panel resolution (1920 x 1080). If it's a
large screen you are wanting, consider a plasma over an LCD. Whilst these
are still more expensive than LCD, world recession has caused the prices of
them to tumble over the last 12 months, and Panasonic give very long
warranties with them. When you go into stores to look at them, make sure
that you grab an erk to demo properly, any that you are interested in. Make
sure that you see a 'standard' definition picture, an HD picture -
preferably from a broadcast source rather than from an HD DVD player - and a
BluRay picture. If the store claims that it can't show you a standard res
picture because they don't have any antenna distribution around the showroom
floor (a common claim because they know that a lot of the sets would produce
a crap picture on such a source), consider looking elsewhere.

Do as much research as you can before committing and parting with your cash.
It really is a much more complex buying exercise, if you don't want to be
disappointed, than it was when you were buying a CRT TV set a few years
back.

Arfa

On 26/02/2010 7:41 PM, N_Cook wrote:
Sylvia wrote in message
...
On 26/02/2010 9:51 AM, Chris wrote:
I am considering the purchase of an LED television. However, before I
do, I would like to know what the difference is between 120& 240hz;
other than the numbers. I've done some research, but there seems to be a
wide array of conflicting opinions. I know that it has to do with
refresh rate, jitter, and blur. So, if anyone has some straightforward
input on the matter, I'm all (grateful) ears.

Thanks

An alien with 240Hz eyes might appreciate[*] the higher frequency
version, but unless you're such an alien living on Earth incognito,
don't waste your money.

Sylvia.

[*] Ignoring the fact that colour displays are finely tuned to the way
that human colour vision works, and an alien would likely wonder what
we'd been smoking.


Ah that explains why I cannot watch these things for more than a few
minutes, I'm an alien. Would anyone know what the equivalent refresh rate is
for good old CRT technology ? As far as fast movement across the image is
concerned, motion jitter or judder or whatever the term is. What refresh
rate would have to be there before I cannot tell the difference between that
part of the technologies?





CRT TVs refresh at 50Hz or 60Hz (near enough) depending on region.

Since a TV program will only contain images (interlaced) at that rate -
or frequently less - a TV that purports to offer a higher refresh rate
will have to create the extra images by some kind of interpolation. If
it does a bad job, then the result will be unwatchable regardless of how
high the refresh rate is.

Sylvia.

On 26/02/2010 8:31 PM, Arfa Daily wrote:
"Phil wrote in message
...

"Arfa Daily"
"Phil Allison"
"William Sommer****** IDIOT"

First, the only televisions that use LEDs use OLEDs. There are none
using
conventional LEDs.


** Fraid " LED TVs " are on sale all over the world right now.

****WIT !!

http://en.wikipedia.org/wiki/LED-backlit_LCD_television



Your Wiki reference says it all. These are NOT LED televisions,

** But they are called " LED TVs " by their makers and so are

*KNOWN BY THAT NAME* to members of the public.


And it's time something was done about that. The manufacturers are
relentlessly plugging this as though it's some new and wonderful display
technology, and it's not (although I have to say that the TV ad campaign
that was running here seems to have stopped now). It is misleading nonsense,
and although all civilised countries have laws against misleading
advertising, for some reason, they seem to be letting this one go,
presumably because like you, they don't have any understanding of what is
actually *meant* by the term, rather than *implied* by it.

But the terms don't have a clearly defined meaning. Indeed, even if they
did, the typical consumer probably wouldn't know what they meant. If
people buy stuff based on not particularly meaningful, but good
sounding, hype, they really have only themselves to blame.

Sylvia.

Sylvia Else wrote in message
...
On 26/02/2010 7:41 PM, N_Cook wrote:
Sylvia wrote in message
...
On 26/02/2010 9:51 AM, Chris wrote:
I am considering the purchase of an LED television. However, before I
do, I would like to know what the difference is between 120& 240hz;
other than the numbers. I've done some research, but there seems to be
a
wide array of conflicting opinions. I know that it has to do with
refresh rate, jitter, and blur. So, if anyone has some straightforward
input on the matter, I'm all (grateful) ears.

Thanks

An alien with 240Hz eyes might appreciate[*] the higher frequency
version, but unless you're such an alien living on Earth incognito,
don't waste your money.

Sylvia.

[*] Ignoring the fact that colour displays are finely tuned to the way
that human colour vision works, and an alien would likely wonder what
we'd been smoking.


Ah that explains why I cannot watch these things for more than a few
minutes, I'm an alien. Would anyone know what the equivalent refresh
rate is
for good old CRT technology ? As far as fast movement across the image
is
concerned, motion jitter or judder or whatever the term is. What refresh
rate would have to be there before I cannot tell the difference between
that
part of the technologies?





CRT TVs refresh at 50Hz or 60Hz (near enough) depending on region.

Since a TV program will only contain images (interlaced) at that rate -
or frequently less - a TV that purports to offer a higher refresh rate
will have to create the extra images by some kind of interpolation. If
it does a bad job, then the result will be unwatchable regardless of how
high the refresh rate is.

Sylvia.

Perhaps its a PAL/NTSC thing. Whatever it is all the LCD TVs I've looked at
with plenty of action/movement on the screen ,I find as irritating as those
digital overlain adverts on hoardings around the sides of TV coverage of
football/soccer viewed on CRT TV. But I don't watch soccer so thats no
problem to me

To the OP , my advice.
Never buy a TV that the seller will only display cartoons on. Try viewing a
source showing plenty of greens and dark sections of images and of course
fast cross-screen mobvement examples.

And why aren't all LCD sets known by the name of the backlight?

Exactly. At least in plasma TVs, the thing producing the light also produces
the image.

And if you really want to get picky... I'm not sure it's really plasma. It's
ionized gas, and the degree of ionization isn't high enough to be considered
a true plasma. I think.

If you are seriously considering the purchase of a flatscreen TV of any
description, the best advice I can give you is to know what you're asking
and seeing in the showroom.

Yes, yes, yes, yes, yes.


Plasma panels also
do not suffer from any viewing angle issues, which can be a problem with
LCDs, particularly if you are thinking of wall-mounting, as most will then
need to be angled down towards your sitting position.

Yes, but... I'm surprised at the wide viewing angles of many LCDs, even
close to the screen. It no longer seems to be a problem, unless the
mishpoche has gathered to watch.


You should also be aware that there are several 'resolutions' of screen
and
drive to take into consideration. Almost all TV showrooms both here and in
the US, tend to have the sets running on at least an HD picture, and often
a
BluRay picture. This makes them look very good at first glance. Problem is
that in normal day to day use when you get it back home, you are going to
be
watching standard resolution terrestrial broadcasts on it, and on many
sets,
these look pretty dreadful, and it is the reason that so many people are
disappointed with their purchase when they get it home, and think that it
is
not what they saw in the store.

Yes and no. Most sets do a poor job upconverting 480i to 1080p, and the
result can be smeary. The solution is to get cable, with many programs
available at native resolutions of 720p or 1080i. The image quality can
equal Blu-ray.


BluRay is a full HD source. This is handled fine by most sets, but be
aware
that if the TV is just HD compatible rather than "Full HD", then the
native
resolution of the actual display panel, will again not match the
resolution
of the signal, and downscaling will take place within the TV to make them
match.

It depends. I have a 32" 720p set in my den, and it has no trouble with
1080i signals.


So, if you are a film buff, and likely to watch stuff on BluRay, you
should
consider a set with a full HD panel resolution (1920 x 1080). If it's a
large screen you are wanting...

....and wanting it you will be...

...consider a plasma over an LCD. Whilst these are still more expensive
than
LCD, world recession has caused the prices of them to tumble over the last
12 months, and Panasonic gives very long warranties with them.

"Home Entertainment" magazine gave a near-frothing-at-the-mouth review to a
48" Panasonic plasma that goes for $1500.

One final point -- don't be overly impressed by the brightest set. Look
critically at the image, with a variety of material.

By the way, I've seen the Samsung "LED" set repeatedly at Fry's. I don't
like it. I can't quite put my finger on it, but it looks "garish". This
might be the way the sample was set up, or it might be inherent. If I were
buying an LCD set, it would probably be a Sony.

Sylvia Else wrote:

CRT TVs refresh at 50Hz or 60Hz (near enough) depending on region.

FYI, Computer CRT screens refresh at 60 to 85 Hz.

The main difference between CRT's and LED's or LCD's is persistance.
The CRT's have long persistance phosphors, when they are illuminated, they
stay lit for a relatively long time. That's why the interlacing system
works, the odd lines are still lit when the even ones are illuminated.

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
New word I coined 12/13/09, "Sub-Wikipedia" adj, describing knowledge or
understanding, as in he has a sub-wikipedia understanding of the situation.
i.e possessing less facts or information than can be found in the Wikipedia.

On 27/02/2010 12:09 AM, Geoffrey S. Mendelson wrote:
Sylvia Else wrote:

CRT TVs refresh at 50Hz or 60Hz (near enough) depending on region.

FYI, Computer CRT screens refresh at 60 to 85 Hz.

The main difference between CRT's and LED's or LCD's is persistance.
The CRT's have long persistance phosphors, when they are illuminated, they
stay lit for a relatively long time. That's why the interlacing system
works, the odd lines are still lit when the even ones are illuminated.

It's not that long, which is why photographs of television pictures look
so awful. Interlacing is used to avoid flicker without having to
transmit 50 or 60 full frames per second.

LCDs don't flicker anyway, regardless of their framerate. The frame rate
issue relates to addressing the judder you get as a result of the image
consisting of a sequence of discrete images, rather than one that
continously varies.

It doesn't help that much TV material that was recorded on film is
transmitted with with odd and even interlaced frames that are scans of
the same underlying image (or some variation thereon), so that the
effective refresh rate considerably lower that the interlaced rate.

Sylvia.

LCDs don't flicker anyway, regardless of their framerate. The frame
rate issue relates to addressing the judder you get as a result of
the image consisting of a sequence of discrete images, rather than
one that continously varies.

Not quite, otherwise the issue would occur with plasma displays. Indeed, it
would with any moving-image recording system.

The problem is that LCDs don't respond "instantaneously". They take a finite
time to go from opaque to the desired transmission level, and then back
again. The result is that the image can lag and "smear". (25 years ago, the
first pocket LCD color TVs from Casio had terrible smear, which added an
oddly "artistic" quality to sports.)

For reasons not clear to me, adding interpolated images reduces the smear.
This makes absolutely no sense whatever, as the LCD now has /less/ time to
switch. I've never gotten an answer on this.


It doesn't help that much TV material that was recorded on film is
transmitted with with odd and even interlaced frames that are scans of
the same underlying image (or some variation thereon), so that the
effective refresh rate considerably lower that the interlaced rate.

Interlaced images can be de-interlaced. Note that most product reviews test
displays for how well they do this.

Dolby has a new thing -- HDR LCD that
modulates the LED backlights on-the-fly.

This is neither new, nor was it invented by Dolby.

CRT TVs refresh at 50Hz or 60Hz (near enough) depending on region.

Since a TV program will only contain images (interlaced) at that rate -
or frequently less - a TV that purports to offer a higher refresh rate
will have to create the extra images by some kind of interpolation. If
it does a bad job, then the result will be unwatchable regardless of how
high the refresh rate is.

Sylvia.

It can get more complicated than that. Dolby has a new thing out HDR LCD
that on the fly modulates the LED backlights for brightness in groups.
that was not possible with CFL LCD backlights.

http://www.dolby.com/uploadedFiles/z...l-overview.pdf


bob

"AZ Nomad" wrote in message
...
On Fri, 26 Feb 2010 00:07:43 +0000, Adrian C wrote:
On 25/02/2010 23:46, William Sommerwerck wrote:
First, the only televisions that use LEDs use OLEDs. There are none
using
conventional LEDs.

none ??

I think when they refer to LEDs, it is LEDs used for backlighting
probably for an LCD.

Yes, that is how it was explained to me from a salesman as well as what I
gathered from online info. So, apparently, it is still an LCD screen. Also,
somehow the refresh rate of the LEDs create some sort of multiplier effect
with the LCDs; thus the higher hz. It sure would be nice to know if this is
correct, and also why/how it enhances the picture.
Although I am far from an expert in this area (hence my original post), I
have the ability to understand just about anything that is explained
correctly. When information is presented in an ambiguous way, which is what
I have seen so far on internet research, that is definitely a red flag that
the author probably is not knowledgable in the subject matter.

In article ,
bob urz wrote:
It can get more complicated than that. Dolby has a new thing out HDR LCD
that on the fly modulates the LED backlights for brightness in groups.
that was not possible with CFL LCD backlights.

Which would be fine if the LEDs corresponded exactly to the pixels. But
they don't.

--
*A plateau is a high form of flattery*

Dave Plowman London SW
To e-mail, change noise into sound.

Dolby has a new thing -- HDR LCD that on the fly
modulates the LED backlights for brightness in groups.

Which would be fine if the LEDs corresponded exactly
to the pixels. But they don't.

I've seen at least one review that complained that local dimming produced
"halos" around objects in darker scenes. I would never, ever buy a set with
such a feature, unless it could be shut off.

"William Sommerwerck" wrote in message
...
If you are seriously considering the purchase of a flatscreen TV of any
description, the best advice I can give you is to know what you're asking
and seeing in the showroom.

Yes, yes, yes, yes, yes.


Plasma panels also
do not suffer from any viewing angle issues, which can be a problem with
LCDs, particularly if you are thinking of wall-mounting, as most will
then
need to be angled down towards your sitting position.

Yes, but... I'm surprised at the wide viewing angles of many LCDs, even
close to the screen. It no longer seems to be a problem, unless the
mishpoche has gathered to watch.


Yes, agreed in general, but it does seem to depend a lot on how much you are
prepared to pay. The point I was making was that LCD screens tend to be
optimised for horizontal viewing angle, and with the supposition that you
will be looking directly at the screen, or even slightly down on it, when it
is sitting on a conventional lounge stand. When it is mounted on a wall, you
will be looking at it from below, and some LCDs - the one I have in my
kitchen, for instance - are not terribly good when viewed from such an
angle. I had to tilt mine down perhaps 10 degrees, after which, it was fine,
so I was just making the point that it's something else to consider *if* the
OP was going for an LCD, and *if* he had any intention of wall mounting it.




You should also be aware that there are several 'resolutions' of screen
and
drive to take into consideration. Almost all TV showrooms both here and
in
the US, tend to have the sets running on at least an HD picture, and
often
a
BluRay picture. This makes them look very good at first glance. Problem
is
that in normal day to day use when you get it back home, you are going to
be
watching standard resolution terrestrial broadcasts on it, and on many
sets,
these look pretty dreadful, and it is the reason that so many people are
disappointed with their purchase when they get it home, and think that it
is
not what they saw in the store.

Yes and no. Most sets do a poor job upconverting 480i to 1080p, and the
result can be smeary. The solution is to get cable, with many programs
available at native resolutions of 720p or 1080i. The image quality can
equal Blu-ray.

Again, yes in principle. But not all sets are equal in this respect, and not
everyone has access to cable, so it was just one more aspect of the
purchasing problem, for the OP to be aware of. I have to say that the 480
upscaling on the Pan plas that I recently bought, is exceptionally good.
Although I have satellite here, with a good few genuine HD channels, I also
watch many SD sat channels, and SD terrestrial digital channels, and the
upscaling to display them on the full HD 1080 panel, is nothing short of
excellent.




BluRay is a full HD source. This is handled fine by most sets, but be
aware
that if the TV is just HD compatible rather than "Full HD", then the
native
resolution of the actual display panel, will again not match the
resolution
of the signal, and downscaling will take place within the TV to make them
match.

It depends. I have a 32" 720p set in my den, and it has no trouble with
1080i signals.

Again, yes. Downscaling seems to be better handled than upscaling in terms
of artifact generation, even on the cheap-end TVs. Again, I was only making
the point in an effort to allow the OP to better understand what he needs to
be looking for, and asking about, to avoid disappointment with his purchase.



So, if you are a film buff, and likely to watch stuff on BluRay, you
should
consider a set with a full HD panel resolution (1920 x 1080). If it's a
large screen you are wanting...

...and wanting it you will be...

...consider a plasma over an LCD. Whilst these are still more expensive
than
LCD, world recession has caused the prices of them to tumble over the
last
12 months, and Panasonic gives very long warranties with them.

"Home Entertainment" magazine gave a near-frothing-at-the-mouth review to
a
48" Panasonic plasma that goes for $1500.

I paid 699 UKP for my 50" Pan plas, so I guess that it's either the same or
a similar spec model to the one they reviewed. There are several variants
depending on features such as how many HDMI ports, and whether or not they
have a built-in sat tuner and so on, but all based on the same basic design.
I have to say that I would give it the same "frothing at the mouth" review
as your Home Entertainment mag. I spent a long long time looking into this,
as I knew that I was going to have a hard job replacing my large-screen Tosh
CRT - which produced superb pictures from all sources -with anything
flat-screen. I knew all along that it was a plas that I wanted really, but
didn't think that I was going to be able to afford one. Now that I've had it
a couple of months, there is absolutely nothing - and I really mean
nothing - that I could pick fault with, so if you are prepared to look long
and hard enough, it is possible to get what you want from this technology.

One other thing that the OP might consider, when he has arrived at a few
models that he might be interested in, is to see what he can find out about
those models by Googling them, and then looking to see what is being said
about them on forums. Many forums have contributors that are hyper-critical
and quite brutal with their comments, and I think that there is a lot to be
learned from trawling these forums. FWIW, before I actually bought my Pan, I
did exactly this, and to my utter surprise, there was barely a single
adverse comment world-wide. The only thing that was commented on by a few
people was that they thought that SD sources displayed on this set, were
perhaps a little 'soft' in terms of contrast, but personally, I didn't find
this either on the showroom model that was demo'd to me, or on the one that
I now actually have. This sort of thing is another reason to understand what
you are asking, and making sure that all these sources and features are
shown to you.



One final point -- don't be overly impressed by the brightest set. Look
critically at the image, with a variety of material.

Yes, 100% agreed



By the way, I've seen the Samsung "LED" set repeatedly at Fry's. I don't
like it. I can't quite put my finger on it, but it looks "garish". This
might be the way the sample was set up, or it might be inherent. If I were
buying an LCD set, it would probably be a Sony.


Yes, agreed on the LED backlit Sammy. I don't like it either, and like you,
can't quite put my finger on exactly why ... My mother owned a 37" Tosh
for a few months before she recently passed on, and that was as good as I
have seen in LCD. I think that if an LCD is the chosen route, it is better
to stick to the big far east names

Arfa

Hi!

Yes, that is how it was explained to me from a salesman as
well as what I gathered from online info. So, apparently, it is
still an LCD screen.

Yes, I'm sure it is. The only thing that's changed is the way the
panel is illuminated so you can see a picture. It used to be that
practically all LCD panels were backlight by a fluorescent tube (or a
set of tubes).

For a variety of reasons, this has changed. (These reasons would be
mercury in fluorescent tubes, lifetime of said tubes as compared to
LEDs, complexity of the driving electronics and energy efficiency.)

The "120Hz" refresh rate would not be hard to achieve. An interlaced
scanning method produces a picture that (in many cases) appears to
flicker much less than a non-interlaced one.

(IBM used to use a similar trick with their 8514 display. It used a
44Hz interlaced vertical scan rate that IBM called an "88Hz" scan
rate. It worked reasonably well, as long as you used an IBM monitor
with longer persistence phosphors and didn't have anything like a
fluorescent light fixture illuminating the room. If you did, the two
tended to "beat" against one another and the effect is annoying. And
if you didn't use an IBM monitor with the special phosphors, that
increased the apparent "flicker" level.)

I don't know how a 240Hz "scan rate" would be achieved. It's probably
a sort of trick that the set's electronics use to make the picture
seem just that much more stable.

William

** And if you put the remark back into its context --
what it IS relevant to becomes obvious.

No it doesn't.

Agreed. It seemed unrelated, even out of left field. I suspect Sylvia didn't
properly express what she wanted to say.

I don't know how a 240Hz "scan rate" would be achieved.
It's probably a sort of trick that the set's electronics use
to make the picture seem just that much more stable.

Actually, it's a frame rate. It can be done by interpolation, by inserting
blank frames, or a combination of the two.

On Fri, 26 Feb 2010 10:20:29 -0800, William Sommerwerck wrote:
I don't know how a 240Hz "scan rate" would be achieved.
It's probably a sort of trick that the set's electronics use
to make the picture seem just that much more stable.

Actually, it's a frame rate. It can be done by interpolation, by inserting
blank frames, or a combination of the two.


or perhaps it's just a flash rate, the pulses powering the LED backlight