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It depends on where you leave the remote."dennis@home" <dennis@killspam.kicks-ass.net> wrote in message
news:gv9ish$9d6$1@news.datemas.de...
"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:bUVRl.11637$Ec5.6994@newsfe27.ams2...
But take account of the fact that we're talking domestic television sets
here, not computer monitors. For the most part, TV sets do not display
the same type of content as a computer monitor, and do not include user
accessible colour temperature presets or adjustments, which is why I
made the point earlier that in general, LCD TVs are set correctly 'out
of the box'.
Every lcd TV I have seen has colour temp adjustments.
What, readily user accessible ?
First of all, your description ignores the compression systems used, andWilliam Sommerwerck wrote:
Mr. Mendelson has little understanding of how digital television works.
Rather than refute his points, I will urge him to find a book on the
subject
and read it.
Actually I do. Why don't you refute my points and that way I can refute
yours
instead of this becoming a pissing contest.
It depends on what you define as a color temperature adjustment. Many (ifEvery lcd TV I have seen has colour temp adjustments.
What, readily user accessible ?
Have you never seen the ones that use a blue LED and a yellow-fluorescentIs there really such a thing as a white LED? The ones I have seen have all
been red/green/blue LEDS on the same substrate to produce what appears to
the eye as a white beam, most of which are far too blue for my taste.
What?They are blue because blue LEDs have a much shorter life than red and
green
so the color will change as they age, and they start out blue before the
end up
a red green mix (yellow/orange).
NTSC does not, and never had, an inherent problem with phase stability.That may be a different story because PAL TV sets never had them. NTSC
sets needed them because the phase of the color carrier wandered and
often shifted to the green, while PAL sets reset the phase each line and
therefore were always "correct".
Because you're seeing them in "torch" mode. There are plenty of good setsI have yet to be impressed by an LCD/PLASMA TV. Every single one of them
I have seen is oversaturated and too bright.
It isn't if you want an accurate rendition of the program material.what makes you think that just one specific colour temp is 'correct'?
Real daylight is all over the place colour temp wise, and the end user
experiences those changes without any problem. Also any self
respecting monitor offers a range of colour temps, since it's nothing
but a taste matter.
I was about to jump on that, but it's basically correct. However, you'd wantMaybe we're talking at cross purposes here, or I'm
not understanding something properly, but it seems to me that the colour
temperature and CRI of the backlighting on an LCD TV, would be crucially
important to correct reproduction of colours.
It has almost nothing to do with it, because the level of each colour
channel output on the screen depends on both the light source and the
settings of the LCD R,G,B channels. Within reason, any temperature
colour backlight can produce any temperature colour picture.
Not in the slightest. Do you even understand the difference between digitalArfa Daily wrote:
I don't know what 'set-ups' this TV has, in terms of brightness, contrast,
colour saturation, tint/hue, but in my experience, most LCD TVs - which is,
after all, what this is - are set correctly 'out of the box', but I accept
that this particular one that I saw might not be a good example of the
technology.
Based on the assumption that it is a PAL set probably brightness,
contrast, and maybe color saturation. Digital TV sets are not PAL per
se, but they still use the same luminance, color, sync, signals that are
used by PAL (and slightly differently by NTSC).
They are also still 25 or 30 frames per second depending upon whether or
not thay are interlaced as in 1080i or not. An interlaced frame is still
2 fields, at 50 or (almost 60Hz) combined.
The main differences between a digital TV signal and an analog one are that
since each frame is discrete, there really is no need for a syncronization
pulse to define the begining of each frame and more importantly, there is
no color subcarrier.
If you were to look at a digital TV signal decoded as if it were a
stream of pixels, you would see something that looked a lot like an
analog TV signal.
dac to generate analog voltages for driving an analog monitor?Computer displays, BTW are red-green-blue with seperate horizontal and vertical
sync, which is very different.
That's analog. Did you never learn that video displays use a video
Actually I do. Why don't you refute my points and that way I can refute yoursMr. Mendelson has little understanding of how digital television works.
Rather than refute his points, I will urge him to find a book on the subject
and read it.
I have no idea of UK law, but in the US and here in Israel, if they useYes Geoff, I'm aware of all that. I work with the technology all the time.
Did you read the original thread from last week ? We were not discussing the
differences between transport and encoding systems, rather the moral - if
not technical - validity of Sammy advertising this new offering of theirs as
a "LED TV", which it isn't. It's an LCD TV with an alternate form of
backlighting (LEDs rather than CCFL).
In theory, yes they can. Since LCD's have very limited control over brightnessOne of the main selling points that they claim, is that because they can
control the intensity of the backlighting in individual areas, they can
deepen the blacks, effectively improving the contrast ratio.
Is there really such a thing as a white LED? The ones I have seen have allOn the example
that I saw last night, I observed no such improvement that was obvious,
compared to the sets around it. The reason that I questioned what controls
for picture setup are available on this particular set, was that given that
the backlighting is formed by RGB LED arrays, not white LEDs, then the
overall colour temperature would in theory be adjustable - sort of a grey
scale adjustment for LCDs, if you like.
That may be a different story because PAL TV sets never had them. NTSCIf this was the case, it might be
accessible to the customer via the standard controls menu, as something like
"tint" or "hue", and the reason that this particular set (they only had the
one on display) did not seem to produce good flesh tones compared to the
sets around it, might be because some sales erk had been playing with the
controls to see if he could 'improve' it ...
I have yet to be impressed by an LCD/PLASMA TV. Every single one of themSomeone - maybe William - commented last week in the original thread, that
they had seen one in Fry's in the U.S., and that they weren't especially
impressed, either.
You havent defined what you mean by a 'photographically usefulmeow2222@care2.com> wrote in message
news:1e56875d-3af4-4041-832c-c511a21147dc@n8g2000vbb.googlegroups.com...
William Sommerwerck wrote:
I guess it comes down to definitions and how 'full spectrum' is
perceived.
Rightly or wrongly, I tend to think of it as a spectrum which contains
the
same component colours in the same ratios, as natural daylight...
That's a reasonable definition for a video display, but it's not
sufficient
for source lighting. It's difficult to make a "full spectrum"
fluorescent
lamp, especially one that produces good color rendition for photograpy.
but I guess even that varies depending on filtering effects of cloud
cover and haze and so on. Even so, I'm sure that there must be some
definition of 'average spectrum daylight', and I would expect that any
display technology would aim to reproduce any colour in as closely
exact a way as it would appear if viewed directly under daylight.
The standard is D6500, a 6500K continuous spectrum from a black-body
source.
What you suggest is, indeed, the intent.
TBH I think this is overplaying the significant of daylight. Almost
any monitor is adjustable to suit preferences of anything from 5000K
to 10,000K, and some go lower. None manke any attempt to copy the
colour spectrum of daylight, they merely include the same colour temp
as daylight as one of the options. None of the major display types
have any ability to copy a daylight spectrum, as they're only RGB
displays.
I think you've missed the difference between recreating the original color
(or the illusion of same), and producing a photographically useful
illuminant. These are different.
light; prints subtract some from the reflected light. Displays makeColor transparencies which are used in pro film applications say your
are a liar.
Not really. Transparencies subtract some colours from the transmitted
fwiw my main set does, and I'm sure its not unique. Generally though ameow2222@care2.com> wrote in message
news:1e56875d-3af4-4041-832c-c511a21147dc@n8g2000vbb.googlegroups.com...
William Sommerwerck wrote:
I guess it comes down to definitions and how 'full spectrum' is
perceived.
Rightly or wrongly, I tend to think of it as a spectrum which contains
the
same component colours in the same ratios, as natural daylight...
That's a reasonable definition for a video display, but it's not
sufficient
for source lighting. It's difficult to make a "full spectrum" fluorescent
lamp, especially one that produces good color rendition for photograpy.
but I guess even that varies depending on filtering effects of cloud
cover and haze and so on. Even so, I'm sure that there must be some
definition of 'average spectrum daylight', and I would expect that any
display technology would aim to reproduce any colour in as closely
exact a way as it would appear if viewed directly under daylight.
The standard is D6500, a 6500K continuous spectrum from a black-body
source.
What you suggest is, indeed, the intent.
TBH I think this is overplaying the significant of daylight. Almost
any monitor is adjustable to suit preferences of anything from 5000K
to 10,000K, and some go lower. None manke any attempt to copy the
colour spectrum of daylight, they merely include the same colour temp
as daylight as one of the options. None of the major display types
have any ability to copy a daylight spectrum, as they're only RGB
displays.
NT
But take account of the fact that we're talking domestic television sets
here, not computer monitors. For the most part, TV sets do not display the
same type of content as a computer monitor, and do not include user
accessible colour temperature presets or adjustments,
because they can be. CRTs are more variable, and the circuits used towhich is why I made
the point earlier that in general, LCD TVs are set correctly 'out of the
box'.
what makes you think that just one specific colour temp is 'correct'?As far as overplaying the significance of daylight goes, I'm not sure that I
follow what you mean by that. If I look at my garden, and anything or
anybody in it, the illumination source will be daylight, and the colours
perceived will be directly influenced by that. If I then reproduce that
image on any kind of artificial display, and use a different reference for
the white, then no other colour will be correct either,
but thats down to historic reasons, customers never expected precisewhich was ever the
case when CRTs were set up to give whites which were either too warm or too
cold, even by a fraction.
It has almost nothing to do with it, because the level of each colourMaybe we're talking at cross purposes here, or I'm
not understanding something properly, but it seems to me that the colour
temperature and CRI of the backlighting on an LCD TV, would be crucially
important to correct reproduction of colours.
Its just a guess. In fact any desired flesh tone can be reproducedAll I know is, is that the flesh tones were poor on the example that I saw,
compared to other LCD TVs which were showing the same picture. The
fundamental difference between those sets and the Sammy, was the CCFL vs LED
backlighting, so it seems reasonable to draw from that, the inference that
the backlighting scheme may well be the cause, no ?
Arfa
What has that have to do with what I said?If you were to look at a digital TV signal decoded as if it were a
stream of pixels, you would see something that looked a lot like an
analog TV signal.
Not in the slightest. Do you even understand the difference between digital
and analog? Put a USB signal from a DMM on a scope and compare that to the
input signal and then get back to us how they are so similar.
The comment that I quoted with the ridiculously idiotic statement thatAZ Nomad wrote:
If you were to look at a digital TV signal decoded as if it were a
stream of pixels, you would see something that looked a lot like an
analog TV signal.
Not in the slightest. Do you even understand the difference between digital
and analog? Put a USB signal from a DMM on a scope and compare that to the
input signal and then get back to us how they are so similar.
What has that have to do with what I said?
If you look at the DECODED signal, which would be a stream of numbers,
Moving the goalposts? Pathetic.
thats only true if you mean you want to watch it at the same colourwhat makes you think that just one specific colour temp is 'correct'?
Real daylight is all over the place colour temp wise, and the end user
experiences those changes without any problem. Also any self
respecting monitor offers a range of colour temps, since it's nothing
but a taste matter.
It isn't if you want an accurate rendition of the program material.
.... not really. The backlight on this monitor is far removed from theMaybe we're talking at cross purposes here, or I'm
not understanding something properly, but it seems to me that the colour
temperature and CRI of the backlighting on an LCD TV, would be crucially
important to correct reproduction of colours.
It has almost nothing to do with it, because the level of each colour
channel output on the screen depends on both the light source and the
settings of the LCD R,G,B channels. Within reason, any temperature
colour backlight can produce any temperature colour picture.
I was about to jump on that, but it's basically correct. However, you'd want
the backlight to be "reasonably close", so you didn't have to push any
channel to its limits of adjustment.
That isn't the way an MPEG is encoded. It's rather more complex.If you look at the DECODED signal, which would be a stream
of numbers, one defining a luminance level and the other defining
a color, and displayed them using an appropriate method, it would
look a lot like an analog signal displayed the same way.
I have to disagree. Suppose the backlight doesn't produce sufficient blueI was about to jump on that, but it's basically correct. However,
you'd want the backlight to be "reasonably close", so you didn't
have to push any channel to its limits of adjustment.
... not really. The backlight on this monitor is far removed from the
colour temp its operating at, and all is well. When its far removed it
does affect contrast ratio a bit.
Ah, so that is why they are backlit then?The Natural Philosopher wrote:
Color transparencies which are used in pro film applications say your
are a liar.
Not really. Transparencies subtract some colours from the transmitted
light; prints subtract some from the reflected light. Displays make
their own...
In the case of an LCD display, that is correct. However, I expect hisAndy Champ wrote:
The Natural Philosopher wrote:
Color transparencies which are used in pro film applications say your
are a liar.
Not really. Transparencies subtract some colours from the transmitted
light; prints subtract some from the reflected light. Displays make
their own...
Ah, so that is why they are backlit then?
So they can 'make their own?
What a prat. An LCD display IS a color transparency.
Andy
Arfa Daily wrote:
Yes Geoff, I'm aware of all that. I work with the technology all the
time.
Did you read the original thread from last week ? We were not discussing
the
differences between transport and encoding systems, rather the moral - if
not technical - validity of Sammy advertising this new offering of theirs
as
a "LED TV", which it isn't. It's an LCD TV with an alternate form of
backlighting (LEDs rather than CCFL).
I have no idea of UK law, but in the US and here in Israel, if they use
LED's in the display, then they can call it an "LED TV". I expect the same
in the UK, I was watching a show from the first season of "The F Word"
(things
take a long time to get here) and they were discussing exactly what could
be
called a sasuage in the UK. Based on what I saw, I expect you would have
trouble fighting them calling a TV with a power on LED an LED TV. :-(
One of the main selling points that they claim, is that because they can
control the intensity of the backlighting in individual areas, they can
deepen the blacks, effectively improving the contrast ratio.
In theory, yes they can. Since LCD's have very limited control over
brightness
then a variable brightness LED behind an LCD will allow them to modulate
the
light level of that particular pixel.
With HD now, the resolution of the panels is high, and the speed of them isI don't know the resolution of the LCD array used in a TV set, but at the
actual crystal level, it's clear (on edge) or colored/transparent (face
out).
I guess if you modulated the polarizing signal you could get levels of
color
out of them, but I thought that the crystals were not fast enough for
that.
On the example
that I saw last night, I observed no such improvement that was obvious,
compared to the sets around it. The reason that I questioned what
controls
for picture setup are available on this particular set, was that given
that
the backlighting is formed by RGB LED arrays, not white LEDs, then the
overall colour temperature would in theory be adjustable - sort of a grey
scale adjustment for LCDs, if you like.
Is there really such a thing as a white LED? The ones I have seen have all
been red/green/blue LEDS on the same substrate to produce what appears to
the eye as a white beam, most of which are far too blue for my taste.
They are blue because blue LEDs have a much shorter life than red and
green
so the color will change as they age, and they start out blue before the
end up
a red green mix (yellow/orange).
Someone - maybe William - commented last week in the original thread,
that
they had seen one in Fry's in the U.S., and that they weren't especially
impressed, either.
I have yet to be impressed by an LCD/PLASMA TV. Every single one of them
I have seen is oversaturated and too bright.
Is there really such a thing as a white LED? The ones I have seen have
all
been red/green/blue LEDS on the same substrate to produce what appears to
the eye as a white beam, most of which are far too blue for my taste.
Have you never seen the ones that use a blue LED and a yellow-fluorescent
pigment?
They are blue because blue LEDs have a much shorter life than red and
green
so the color will change as they age, and they start out blue before the
end up
a red green mix (yellow/orange).
What?
I have never seen a dead LED (though I assume they exist), nor have I
heard
of LEDs becoming dimmer with age.