Bit of a Con Really - Follow-up ...

[Dave Plowman (News)]

In article <Z_8Sl.165924$A85.12428@newsfe03.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:

I think that I would have to contest your point of "very limited
control". All of the (recent) half-way decent LCD screens that I have
seen to date, have a perfectly adequate contrast ratio. Certainly, the
one in my kitchen produces deep enough blacks and bright enough whites
to be absolutely fine under the pretty intense flourescent light that I
have in there. This is one of the reasons that I question the
requirement to extinguish areas of the backlighting in order to
'improve' the rendition of blacks.

If you're just watching casually under high ambient lighting, the quality
of the blacks is pretty irrelevant. It's when you're doing some serious
viewing under subdued lighting that it matters. And this is exactly where
ordinary backlit LCD falls over against CRT.

--
*Who is this General Failure chap anyway - and why is he reading my HD? *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[Andy Champ]

The Natural Philosopher wrote:

Andy 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.

Dear me. Got out of bed the wrong side today? You do seem to be

getting a little impolite lately! Anyway...

Unlike a slide (usually shown with a halogen lamp) or a print (usually
shown under whatever ambient light is about) most LCD displays have a
backlight specially chosen by the manufacturer to meet some compromise
of (good colour, cheap, low power, probably something else I can't think
of) when operating with the particular LCD filters in front of them.

A slide has a pretty good match to the colours of the real scene. It
has to, because the slide manufacturer didn't make the projector.

There's no such requirement for a display - it's the light emitted by
the entire combination of backlight and filters that matters.

OK?

Andy

 

[Arfa Daily]

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:50606967f5dave@davenoise.co.uk...

In article <Z_8Sl.165924$A85.12428@newsfe03.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:
I think that I would have to contest your point of "very limited
control". All of the (recent) half-way decent LCD screens that I have
seen to date, have a perfectly adequate contrast ratio. Certainly, the
one in my kitchen produces deep enough blacks and bright enough whites
to be absolutely fine under the pretty intense flourescent light that I
have in there. This is one of the reasons that I question the
requirement to extinguish areas of the backlighting in order to
'improve' the rendition of blacks.

If you're just watching casually under high ambient lighting, the quality
of the blacks is pretty irrelevant. It's when you're doing some serious
viewing under subdued lighting that it matters. And this is exactly where
ordinary backlit LCD falls over against CRT.

--
*Who is this General Failure chap anyway - and why is he reading my HD? *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

Granted, but this is a general entertainment device. When does anyone do any
'serious' viewing on a TV set, especially a not-very-special 32" LCD ? These
things are designed to have Coronation Street watched on them in normal,
averagely lit lounges really. I've seen some of the Sony offerings that are
intended as 'serious' home cinema displays, displayed in subdued lighting
demo rooms. One that I was particulary impressed by, was in a Sony store in
Vegas. That set had standard constant intensity CCFL backlighting, and I
don't recall thinking that there was any problem at all with the way it
rendered blacks. Have you had a look at one of these LED backlit Sammys yet
Dave ? As you are involved with the broadcast business - allbeit on the
sound side rather than the vision - I would be interested to know what you
make the picture compared to others. Waitrose have them, so I guess John
Lewis would as well, as well as the Currys barns, probably.

Arfa

 

[William Sommerwerck]

a pretty good match to the colours of the real scene.
It has to, because the slide manufacturer didn't make the projector.

That's not really right...

The color rendition of a transparency -- or print -- is intended to be
"correct" under a specific illuminant, usually one with a continous
spectrum, at a specific color temperature.

For the colors in a print or transparency to be "correct" in any absolute
sense -- that is, to actually "match" the colors of the original scene --
they would have to have the same spectral characteristics. They rarely do.
And they don't have to, if the way the eye is stimulated is close.

There's no such requirement for a display -- it's the light emitted
by the entire combination of backlight and filters that matters.

Exactly the same thing applies to prints and transparencies. What the eye &
brain think they see is all that matters.

OK?

Nope. See preceding.

 

[Dave Plowman (News)]

In article <s0eSl.201349$Oi7.155136@newsfe23.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:

If you're just watching casually under high ambient lighting, the
quality of the blacks is pretty irrelevant. It's when you're doing
some serious viewing under subdued lighting that it matters. And this
is exactly where ordinary backlit LCD falls over against CRT.

Granted, but this is a general entertainment device. When does anyone do
any 'serious' viewing on a TV set, especially a not-very-special 32" LCD
?

Me, for one. Some things I like to watch properly - not just glance at.
And it's not so very long ago a 28" CRT was pretty well top of the range.
But when I do sit down to watch TV I do it under controlled lighting
conditions - and through a good stereo sound system too. I want to see it
at its best.

These things are designed to have Coronation Street watched on them in
normal, averagely lit lounges really.

Maybe, but then so was every TV ever made.

I've seen some of the Sony
offerings that are intended as 'serious' home cinema displays, displayed
in subdued lighting demo rooms. One that I was particulary impressed by,
was in a Sony store in Vegas. That set had standard constant intensity
CCFL backlighting, and I don't recall thinking that there was any
problem at all with the way it rendered blacks. Have you had a look at
one of these LED backlit Sammys yet Dave

No - I'm not in the market for a new TV yet.

? As you are involved with the
broadcast business - allbeit on the sound side rather than the vision -
I would be interested to know what you make the picture compared to
others. Waitrose have them, so I guess John Lewis would as well, as well
as the Currys barns, probably.

All I do know was I worked on an HD TV shoot recently where the monitors
were all LCD HD (and Pro ones so I assume state of the art). And on the
numerous night scenes the LD was relying totally on his scope to set black
level rather than the monitor. Which was displaying various shades of grey
where it should have been black. Quite a 'contrast' from the Grade 1 CRT
location monitors which were used for SD.

--
*Oh, what a tangled website we weave when first we practice *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[dennis@home]

"The Natural Philosopher" <tnp@invalid.invalid> wrote in message
news:gvaos7$gug$2@news.albasani.net...

Andy 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.

No it is not!

A transparency is a subtractive process.
An lcd is additive.

Each pixel in a film transparency has three filter layers each of which can
absorb a colour.

Each pixel on an lcd is made from three different colour subpixels.
The subpixels each have a colour filter behind them to make them RGorB.

Andy

 

[Dave Plowman (News)]

In article <9dWdnXC6QOx494TXnZ2dnUVZ8iSdnZ2d@eclipse.net.uk>,
Andy Champ <no.way@nospam.invalid> wrote:

So they can 'make their own?
What a prat. An LCD display IS a color transparency.

Dear me. Got out of bed the wrong side today? You do seem to be
getting a little impolite lately! Anyway...

It's not a bad analogy.

Unlike a slide (usually shown with a halogen lamp) or a print (usually
shown under whatever ambient light is about) most LCD displays have a
backlight specially chosen by the manufacturer to meet some compromise
of (good colour, cheap, low power, probably something else I can't think
of) when operating with the particular LCD filters in front of them.

LCD backlights are usually chosen to have a pretty good spectral response.

A slide has a pretty good match to the colours of the real scene. It
has to, because the slide manufacturer didn't make the projector.

But then different makes of transparencies give different results...

There's no such requirement for a display - it's the light emitted by
the entire combination of backlight and filters that matters.

How about LCD projectors?

--
*Why is it that to stop Windows 95, you have to click on "Start"?

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[tony sayer]

All I do know was I worked on an HD TV shoot recently where the monitors
were all LCD HD (and Pro ones so I assume state of the art). And on the
numerous night scenes the LD was relying totally on his scope to set black
level rather than the monitor. Which was displaying various shades of grey
where it should have been black. Quite a 'contrast' from the Grade 1 CRT
location monitors which were used for SD.

Is anyone making grade one CRT monitors or hi spec CRT's still?...
--
Tony Sayer

 

[William Sommerwerck]

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".

NTSC does not, and never had, an inherent problem with phase stability.

I cant conclude anything, but I know 2 things:
1. NTSC is widely known as Never The Same Color twice
2. The PAL system includes measures to counter phase shift causing
colour issues, so I can only conclude that the system engineers
thought this was a problem with NTSC.

I don't have the time to discuss this at length, but NTSC's unfortunate
reverse-acronym was the result of poor studio standards, and is not inherent
in the system. PAL incorporated phase alternation to partly compensate for
transmission problems (non-linear group delay) in Europe.

And fwiw, IIUC PAL rendered colours are designed to alternate the
error line after line rather than get each line colour correct, so
like many such measures it usually solves the problem, but not always.

Correct. That's why color errors roughly cancelled out, at the expense of
loss of satruation.

 

[tony sayer]

In article <gvcars$tjr$1@news.eternal-september.org>, William
Sommerwerck <grizzledgeezer@comcast.net> scribeth thus

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".

NTSC does not, and never had, an inherent problem with phase stability.

I cant conclude anything, but I know 2 things:
1. NTSC is widely known as Never The Same Color twice
2. The PAL system includes measures to counter phase shift causing
colour issues, so I can only conclude that the system engineers
thought this was a problem with NTSC.

I don't have the time to discuss this at length, but NTSC's unfortunate
reverse-acronym was the result of poor studio standards, and is not inherent
in the system. PAL incorporated phase alternation to partly compensate for
transmission problems (non-linear group delay) in Europe.

Wasn't something done to either the NTSC transmission spec or the sets
that largely alleviated that .. sometime after the original system
started?..

And fwiw, IIUC PAL rendered colours are designed to alternate the
error line after line rather than get each line colour correct, so
like many such measures it usually solves the problem, but not always.

Correct. That's why color errors roughly cancelled out, at the expense of
loss of satruation.

Simple PAL and de luxe PAL IIRC but it was a long time ago now..
--
Tony Sayer

 

[The Natural Philosopher]

Andy Champ wrote:

The Natural Philosopher wrote:
Andy 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.

Dear me. Got out of bed the wrong side today? You do seem to be
getting a little impolite lately! Anyway...

Unlike a slide (usually shown with a halogen lamp) or a print (usually
shown under whatever ambient light is about) most LCD displays have a
backlight specially chosen by the manufacturer to meet some compromise
of (good colour, cheap, low power, probably something else I can't think
of) when operating with the particular LCD filters in front of them.

A slide has a pretty good match to the colours of the real scene. It
has to, because the slide manufacturer didn't make the projector.

There's no such requirement for a display - it's the light emitted by
the entire combination of backlight and filters that matters.

OK?

Andy

No transparency can show a spectral section that isn't in the spectrum
of the illuminant.

Which is why monochromatic backlights or projector light sources are not
used.

I challenge you to e.g. produce a natural colour with a sodium lamp..no
matter how you tweak the color dyes.

 

[The Natural Philosopher]

dennis@home wrote:

"The Natural Philosopher" <tnp@invalid.invalid> wrote in message
news:gvaos7$gug$2@news.albasani.net...
Andy 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.

No it is not!

A transparency is a subtractive process.
An lcd is additive.

Think again.

Each pixel in a film transparency has three filter layers each of which
can absorb a colour.

I've not heard of pixels with respect to film before. Make it up as we
go along?

Each pixel on an lcd is made from three different colour subpixels.
The subpixels each have a colour filter behind them to make them RGorB.

Which amounts to the same thing in practice.

50% on two colors and 0 on another in film = LCD primary.

As far as the eye is concerned. The issue being that the colours in all
cases are relatively broad spectrum colours. You cant get monochromatic
colour with either system if you want overall balance. You are not
mixing pure red, pure blue and pure green any more than you are notching
out everything BUT pure magenta pure cyan or pure yellow..

Andy

 

[The Natural Philosopher]

Dave Plowman (News) wrote:

In article <9dWdnXC6QOx494TXnZ2dnUVZ8iSdnZ2d@eclipse.net.uk>,
Andy Champ <no.way@nospam.invalid> wrote:
So they can 'make their own?
What a prat. An LCD display IS a color transparency.

Dear me. Got out of bed the wrong side today? You do seem to be
getting a little impolite lately! Anyway...

It's not a bad analogy.

Unlike a slide (usually shown with a halogen lamp) or a print (usually
shown under whatever ambient light is about) most LCD displays have a
backlight specially chosen by the manufacturer to meet some compromise
of (good colour, cheap, low power, probably something else I can't think
of) when operating with the particular LCD filters in front of them.

LCD backlights are usually chosen to have a pretty good spectral response.

A slide has a pretty good match to the colours of the real scene. It
has to, because the slide manufacturer didn't make the projector.

But then different makes of transparencies give different results...

And transparencies are usually used for top quality magazine prints not

'projected onto a screen' anyway.

There's no such requirement for a display - it's the light emitted by
the entire combination of backlight and filters that matters.

How about LCD projectors?

 

[The Natural Philosopher]

William Sommerwerck wrote:

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".

NTSC does not, and never had, an inherent problem with phase stability.

I cant conclude anything, but I know 2 things:
1. NTSC is widely known as Never The Same Color twice
2. The PAL system includes measures to counter phase shift causing
colour issues, so I can only conclude that the system engineers
thought this was a problem with NTSC.

I don't have the time to discuss this at length, but NTSC's unfortunate
reverse-acronym was the result of poor studio standards, and is not inherent
in the system.

It is. Multipath effects caused unacceptable phase and color shifts.

NTSC worked fine on cable, but never as a medium for over air
transmissin with any HINT of multipath.

PAL incorporated phase alternation to partly compensate for

transmission problems (non-linear group delay) in Europe.

sorry, that's a factor of ANY RF tranmission where more than one path to

teh receiver exists.

And fwiw, IIUC PAL rendered colours are designed to alternate the
error line after line rather than get each line colour correct, so
like many such measures it usually solves the problem, but not always.

Correct. That's why color errors roughly cancelled out, at the expense of
loss of satruation.

? huh?

 

William Sommerwerck wrote:

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.

... 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.

I have to disagree. Suppose the backlight doesn't produce sufficient blue
for the desired color temperature. You can compensate by displaying the blue
pixels at a higher luminance level. But you can't go higher than 100% -- the
lightest (highest) level the LCD can transmit. That level might not be
enough to match the green and red levels.

indeed, but you'd have to have a huge mismatch between backlight CCT
and displayed image CCT for that problem to occur. A 15,000K backlight
with a 5000K display works just fine.

A roughly similar situation occurs with color-negative film. If you expose
daylight-balanced film at 2800K, the blue layer might be unacceptably
underexposed, and no amount of additional blue-layer exposure during
printing will restore the lost shadow detail. Ditto for exposing 3200K film
under daylight, except the error is on the side of overexposure.

yes that happens with film, but nothing like it happens with an LCD
display. What happens is that if your image is far removed from the
backlight in terms of CCT, then one of the RGB LCD colour channels
operates over part of its potential range, not the full range. So for
example on this display the B pixels might never exceed 50% light
transmission. It doesnt cause a problem.

Simply stated, neither an LCD nor photographic film can display or record an
infinite brightness range.

of course


NT

 

[dennis@home]

"The Natural Philosopher" <tnp@invalid.invalid> wrote in message
news:gvcdq8$oon$1@news.albasani.net...

dennis@home wrote:


"The Natural Philosopher" <tnp@invalid.invalid> wrote in message
news:gvaos7$gug$2@news.albasani.net...
Andy 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.

No it is not!

A transparency is a subtractive process.
An lcd is additive.

Think again.

I have, you are still wrong.

Each pixel in a film transparency has three filter layers each of which
can absorb a colour.


I've not heard of pixels with respect to film before. Make it up as we go
along?

Each pixel on an lcd is made from three different colour subpixels.
The subpixels each have a colour filter behind them to make them RGorB.

Which amounts to the same thing in practice.

No it does not.

You need different spectra for an additive system and a subtractive system.

 

[Dave Plowman (News)]

In article <bpNlUMBU3XGKFwzo@bancom.co.uk>,
tony sayer <tony@bancom.co.uk> wrote:

All I do know was I worked on an HD TV shoot recently where the
monitors were all LCD HD (and Pro ones so I assume state of the art).
And on the numerous night scenes the LD was relying totally on his
scope to set black level rather than the monitor. Which was displaying
various shades of grey where it should have been black. Quite a
'contrast' from the Grade 1 CRT location monitors which were used for
SD.


Is anyone making grade one CRT monitors or hi spec CRT's still?...

I'm told they are - but not the small sizes which also run off batteries
for location use.

--
*One nice thing about egotists: they don't talk about other people.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[Dave Plowman (News)]

In article <gvcds3$oon$2@news.albasani.net>,
The Natural Philosopher <tnp@invalid.invalid> wrote:

But then different makes of transparencies give different results...

And transparencies are usually used for top quality magazine prints not
'projected onto a screen' anyway.

And are adjusted as part of the printing process.

--
*If love is blind, why is lingerie so popular? *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

William Sommerwerck wrote:

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".

NTSC does not, and never had, an inherent problem with phase stability.

I cant conclude anything, but I know 2 things:
1. NTSC is widely known as Never The Same Color twice
2. The PAL system includes measures to counter phase shift causing
colour issues, so I can only conclude that the system engineers
thought this was a problem with NTSC.

And fwiw, IIUC PAL rendered colours are designed to alternate the
error line after line rather than get each line colour correct, so
like many such measures it usually solves the problem, but not always.

I have yet to be impressed by an LCD/PLASMA TV. Every single one of them
I have seen is oversaturated and too bright.

isnt that just an adjustment thing? And yes, I agree many wont go dim
enough, but some do.


NT

 

[Dave Plowman (News)]

In article <gvcars$tjr$1@news.eternal-september.org>,
William Sommerwerck <grizzledgeezer@comcast.net> wrote:

I don't have the time to discuss this at length, but NTSC's unfortunate
reverse-acronym was the result of poor studio standards, and is not
inherent in the system. PAL incorporated phase alternation to partly
compensate for transmission problems (non-linear group delay) in Europe.

IIRC, nowt to do with studios, but the transmission process. Hence the
tint control on NTSC sets which is absent on PAL ones.

If I remember my BBC training correctly, NTSC gives theoretically better
'studio' pictures than PAL. Obviously ignoring line and frame frequency.
PAL best for VTR recording, and SECAM the best for transmission.

--
*Pentium wise, pen and paper foolish *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.