Leonard Caillouet wrote:
Again, while it is true that you can make any color within a given gamut
with some combination of R,G, & B, it is NOT true that you will get the
CORRECT color for ALL colors if the decoding matrix is not correct (very
common in many consumer sets over the years, if the gamut is wrong, if the
gray scale is wrong, or if the spectrum is wrong. To get the right mix of
colors for all colors in a given system, you have to play by the rules for
that system. If you change them, such as is the case when you deviate in
spectral response from the CIE curves, you have to make it up somewhere
else. This gets very complicated and is precisely why some people who are
sensitive to color reproduction have noticed that LED based displays have
had trouble with some colors.

I think that the important point is that the CIE standards are a subset
of colors, not the millions of colors people think they are getting from
a computer display.

Geoff.


--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM

The Natural Philosopher wrote:
wrote:
The Natural Philosopher wrote:

You would think so really, but going back to film photography, there are
reasons why portraits were always shot on e.g. Konica, landscapes on
Agfa or Fuji, , and no one used Kodak at all professionally - Except for
Kodachrome..

NT

Film is a whole nother business. You've got a lot less control over
its 'colour settings' than you have with a display screen, and ditto
re optical linearity. The issues with an LCD screen are quite
different.

well in the sense that they all use combinations of RGB (or CYMK) to
produce a 'full colour spectrum'and none succeed perfectly for all
applications, they are considerably identical, actually.

You can't tweak the colour response of film, you can with CRTs or LCDs.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

The Natural Philosopher wrote:
wrote:
Schrodinger's cat wrote:
"The Natural Philosopher" wrote in message
...
wrote:
The Natural Philosopher wrote:
You would think so really, but going back to film photography,
there are
reasons why portraits were always shot on e.g. Konica, landscapes on
Agfa or Fuji, , and no one used Kodak at all professionally -
Except for
Kodachrome..

NT
Film is a whole nother business. You've got a lot less control over
its 'colour settings' than you have with a display screen, and ditto
re optical linearity. The issues with an LCD screen are quite
different.

well in the sense that they all use combinations of RGB (or CYMK) to
produce a 'full colour spectrum'and none succeed perfectly for all
applications, they are considerably identical, actually.

No, they aren't.

Very basically, you have to understand that:

A printed image is sending reflected light to your eye. It can only
reflect
some portion of the spectrum of light it has absorbed.

A screen is is sending transmitted light to your eye, which has no
reflective element to speak of.

Put even more simply, a printed image varies dramatically under
different
lighting conditions, unlike a screen.

They could hardly be less identical and the analogy with different
brands of
film is not applicable at all.

HTH

issues very different.
Proof by assertion.

Go read some textbooks on the subject of colour management for screen &
print. The topic is far too complex to sum up from first principles in a
newsgroup post.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

wrote:
The Natural Philosopher wrote:
wrote:
Schrodinger's cat wrote:
"The Natural Philosopher" wrote in message
...
wrote:
The Natural Philosopher wrote:
You would think so really, but going back to film photography, there are
reasons why portraits were always shot on e.g. Konica, landscapes on
Agfa or Fuji, , and no one used Kodak at all professionally - Except for
Kodachrome..

NT
Film is a whole nother business. You've got a lot less control over
its 'colour settings' than you have with a display screen, and ditto
re optical linearity. The issues with an LCD screen are quite
different.

well in the sense that they all use combinations of RGB (or CYMK) to
produce a 'full colour spectrum'and none succeed perfectly for all
applications, they are considerably identical, actually.

No, they aren't.

Very basically, you have to understand that:

A printed image is sending reflected light to your eye. It can only reflect
some portion of the spectrum of light it has absorbed.

A screen is is sending transmitted light to your eye, which has no
reflective element to speak of.

Put even more simply, a printed image varies dramatically under different
lighting conditions, unlike a screen.

They could hardly be less identical and the analogy with different brands of
film is not applicable at all.

HTH
issues very different.
Proof by assertion.

I find it hard to believe that anyone could think the same controls
were available to them with a paper/transparency process as with a
computer monitor. I cant think of any possible motivation to prove
whats quite obvious to anyone's that done photographic printing.

Indeed.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

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...

And LCDs use a matrix of RGB filters over a backlight, which makes them
behave similarly to a transparency in a projector, with the exception
that you can tweak the RGB values to change the colour balance - which
you *can't* do with film transparencies.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

In article ,
Bob Larter wrote:
You can't tweak the colour response of film,

You can during processing.

--
*All those who believe in psychokinesis, raise my hand *

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

Dave Plowman (News) wrote:
In article ,
The Natural Philosopher 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.

Which process is an entire art & science of its own. It is *not* easy to
do a good job of converting an RGB light image into CMYK pigments.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

dennis@home wrote:


"The Natural Philosopher" wrote in message
...
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.

Um, this sounds a little confused. The important distinction is between
*additive* colour (eg; RGB) vs *subtractive* colour (eg; CMYK).
With RGB, you're *filtering* a full spectrum illuminant, with CMYK,
you're *absorbing* part of a full spectrum illuminant.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

wrote:
John wrote:
"Archie" wrote in message
...
wrote in message
...
Arfa Daily wrote:
"Geoffrey S. Mendelson" wrote in message
...
Arfa Daily wrote:

Well, I saw one of these LED backlit TV sets from Sammy in a store last
night, and I have to say that I was not particularly impressed with the
picture quality. Comparing to conventionally backlit (CCFL) Sony and
Panasonic offerings in immediate proximity to the Sammy, it was my
opinion
that the rendition of skin tones, which we previously agreed was a good
test
of a colour display's performance, was actually nothing like as good.
Both
the Pan and the Sony had a near identical 'tone' to the skin of a
newsreader's face. On the Sammy, that same face was rather pink and
florid
looking. I also did not think that the black level was any better than
on
the other two sets, which is a point that they are making a lot of,
claiming
that it substantially increases the contrast ratio.

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

P'raps it needs degausing - or the convergence tweaking!

Ahh - my old Dynatron with 27 pots on a hinged panel to play with.

thats one thing I DON'T miss. I thanked god for inline guns.

Ayup. When I was a kid, our first colour set was a 27" Baird, which had
a huge, hinged PCB with a kazillion pots on it, & an acetate overlay
covering the whole thing, with diagrams printed on it to show what each
pot adjusted. *Lots* of fun!

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Leonard Caillouet wrote:
wrote in message
...
William Sommerwerck wrote:
The LCD only filters light from the backlight. If you don't have a
full
spectrum white in the first place the you can't expect decent colour.

Not so. All you have to do is hit the defined points in CIE diagram. The
Pioneer plasma sets hit them dead-on.

Indeed. None of the major display techologies deliver full spectrum,
nor do they need to.


NT


This is true only if you have custom LUTs or decoding algorithms for a
display based on the relationship between the spectra of the lighting
and the CIE standard observer functions that cameras are generally
aligned to approximate. The other thing that no one mentions is that
trying to make up for spectral shortcomings with different filters and
decoding reduces the efficiency of the lighting system.

Of course.

There is usually a "rest of the story" beyond the naive assumptions that
get thrown around about reproducing color. This thread is full of
examples.

Those of us who take colour reproduction seriously use colourimeters to
calibrate the screen & display card LUTs.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Bob Larter wrote:
You can't tweak the colour response of film, you can with CRTs or LCDs.

People have been known to do it with Ektachrome type film (Ektachrome,
Fijuchrome, AgfaChrome, Ilfochrome, etc) with varying success by tweaking
the exposure and development.

At one time you could get Kodachrome developed to spec, which was
intended to correct for mistakes in exposure, but it certainly would
change color response.

In the printing process, either to film (used in movies) or paper, you
could do all sorts of things.

Standard C-41 color film has an exposure latitude of less than one stop
underexposure, but 4-5 stops of overexposure. As the exposure increases,
color response, contrast and graniness change. If you like fine grained over
saturated colors, try shooting a roll of ISO 100 color negative film and
have it processed normally.

Technicolor which is actually a black and white negative process (producing
seperate red, green and blue negatives on black and white film) could very
easily be manipulated and often was. Look at the recent prints (or the
DVD from them) of The Wizard of Oz.

The original intention was to produce a movie that was almost cartoon
like in its color, later prints were much more subdued, almost "normal"
in color as well as the video tapes made from them.

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM

Leonard Caillouet wrote:
wrote in message
...
Leonard Caillouet wrote:
wrote in message
...
William Sommerwerck wrote:
The LCD only filters light from the backlight. If you don't have a
full
spectrum white in the first place the you can't expect decent
colour.

Not so. All you have to do is hit the defined points in CIE diagram.
The
Pioneer plasma sets hit them dead-on.

Indeed. None of the major display techologies deliver full spectrum,
nor do they need to.


NT


This is true only if you have custom LUTs or decoding algorithms for a
display based on the relationship between the spectra of the lighting and
the CIE standard observer functions that cameras are generally aligned to
approximate.

What that has to do with it I dont know. If you find an RGB display
with violet output, I'm all ears.


NT


It has everything to do with accurate reproduction of color in video.

What you seem to miss is that the underlying assumption in color
reproduction in video is that the display and the camera both approximate
the CIE standard observer curves for red, green, and blue spectral response.
If this is the case, and you encode properly, you can use a standard
decoding matrix on the display end and get a reasonable reproduction of what
was recorded. If you have a very narrow spectrum on either end, some colors
will be reproduced with less energy than with the proper spectrum. This can
be compensated for using a customized matrix or LUTs.

Again, while it is true that you can make any color within a given gamut
with some combination of R,G, & B, it is NOT true that you will get the
CORRECT color for ALL colors if the decoding matrix is not correct (very
common in many consumer sets over the years, if the gamut is wrong, if the
gray scale is wrong, or if the spectrum is wrong. To get the right mix of
colors for all colors in a given system, you have to play by the rules for
that system. If you change them, such as is the case when you deviate in
spectral response from the CIE curves, you have to make it up somewhere
else. This gets very complicated and is precisely why some people who are
sensitive to color reproduction have noticed that LED based displays have
had trouble with some colors.

Leonard

I agree with what you're saying, it just wasnt the point I was
addressing.


NT

Bob Larter wrote:
The Natural Philosopher wrote:
wrote:
The Natural Philosopher wrote:

You would think so really, but going back to film photography, there
are
reasons why portraits were always shot on e.g. Konica, landscapes on
Agfa or Fuji, , and no one used Kodak at all professionally - Except
for
Kodachrome..

NT

Film is a whole nother business. You've got a lot less control over
its 'colour settings' than you have with a display screen, and ditto
re optical linearity. The issues with an LCD screen are quite
different.

well in the sense that they all use combinations of RGB (or CYMK) to
produce a 'full colour spectrum'and none succeed perfectly for all
applications, they are considerably identical, actually.

You can't tweak the colour response of film, you can with CRTs or LCDs.

You can actually.

Bob Larter 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...

And LCDs use a matrix of RGB filters over a backlight, which makes them
behave similarly to a transparency in a projector, with the exception
that you can tweak the RGB values to change the colour balance - which
you *can't* do with film transparencies.

Why do color enlargers come equipped with color filters then?

This is simply not true. Every display has a color gamut that is
limited by the maximum saturation of its primaries. You can
produce any color within that gamut but not any outside.

Correct.


Even if every flesh tone is in that gamut, that does not mean that
you will get the right flesh tones for a given combination of RGB.
In order to do so, you must have the same spectrum in the
primaries that you have in the camera filters...

This bothers me. It might be true in a practical sense, but it's always
struck me as being theoretically wrong (mostly because of the extreme
overlap of the eye's blue and green receptors). I won't start an argument,
though, because, even if my intuition is correct, I don't have the "science"
to back it up.

You can during processing.

How? The film's color response is basically set by the choice of
sensitizers.

You can adjust the balance, but that's not the same thing.

Arfa Daily wrote:
"William Sommerwerck" wrote in message
...
The LCD only filters light from the backlight. If you don't have a full
spectrum white in the first place the you can't expect decent colour.
White LEDs aren't quite there yet are they?
Absolutely true, except that this particular TV doesn't use white LEDs in
its 'revolutionary' backlighting scheme. It uses small RGB arrays, which
is
why I was questioning whether there was any control over the individual
elements in each array, such that the colour temperature of the nominally
white light that they produce, could be varied. Which would then, of
course,
have a corresponding effect on the displayed colour balance. It just
seemed
to me that given they have gone to the trouble of using RGB arrays,
rather
than white LEDs, the reason for that might have been to get a full(er)
spectrum white.
In a very broad sense, the last thing you want is a "full-spectrum" light.
The standard primaries are diluted with too much white as it is.



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, but I guess
even that varies depending on filtering effects of cloud cover and haze and
so on.

It does. One specifies that with colour temperature. Eg; direct sunlight
is about 5000K, while shade is up around 6500K, & tungsten light bulbs
are down around 2400K. Higher temperatures are biased towards blue,
lower are biased towards red. The white balance of a screen or an image
is specified in the same way.


Even so, I'm sure that there must be some definition of 'average
spectrum daylight',

There is: 6500K, which is what I have my monitors calibrated to.
Traditionally, the print (CMYK) media use 5500K.

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.

In general, that's true, although it's common for LCD monitors to have a
factory WB of as much as 8000K, as it makes the image zappier.



--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

"Bob Larter" wrote in message
...
dennis@home wrote:


"The Natural Philosopher" wrote in message
...
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.

Um, this sounds a little confused. The important distinction is between
*additive* colour (eg; RGB) vs *subtractive* colour (eg; CMYK).
With RGB, you're *filtering* a full spectrum illuminant, with CMYK, you're
*absorbing* part of a full spectrum illuminant.

Its only confusing to people that don't understand that backlit LCDs, like
CRTs, add three primary colours together to make a colour image.
The source (phosphors or white light tubes/LEDs with colour filters) of the
primary colours may vary but the process is the same.

It is not the same as a slide which filters each pixel (that's picture
element to the one who claimed slides don't have pixels) through several
coloured layers or prints that do it with inks of various shades.

The Natural Philosopher wrote:
Schrodinger's cat wrote:


"The Natural Philosopher" wrote in message
...
wrote:
The Natural Philosopher wrote:

You would think so really, but going back to film photography,
there are
reasons why portraits were always shot on e.g. Konica, landscapes on
Agfa or Fuji, , and no one used Kodak at all professionally -
Except for
Kodachrome..

NT

Film is a whole nother business. You've got a lot less control over
its 'colour settings' than you have with a display screen, and ditto
re optical linearity. The issues with an LCD screen are quite
different.

well in the sense that they all use combinations of RGB (or CYMK) to
produce a 'full colour spectrum'and none succeed perfectly for all
applications, they are considerably identical, actually.

No, they aren't.

Very basically, you have to understand that:

A printed image is sending reflected light to your eye. It can only
reflect some portion of the spectrum of light it has absorbed.

Color transparencies which are used in pro film applications say your
are a liar.

Colour transparencies aren't printed images.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

The Natural Philosopher wrote:
Bob Larter 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...

And LCDs use a matrix of RGB filters over a backlight, which makes
them behave similarly to a transparency in a projector, with the
exception that you can tweak the RGB values to change the colour
balance - which you *can't* do with film transparencies.

Why do color enlargers come equipped with color filters then?

You're completely missing the point. Once again, projected colour
transparencies are nothing like printed images.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Dave Plowman (News) wrote:
In article ,
Bob Larter wrote:
You can't tweak the colour response of film,

You can during processing.

Yeah, okay, you can, but it's rarely done.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Geoffrey S. Mendelson wrote:
Bob Larter wrote:
You can't tweak the colour response of film, you can with CRTs or LCDs.

People have been known to do it with Ektachrome type film (Ektachrome,
Fijuchrome, AgfaChrome, Ilfochrome, etc) with varying success by tweaking
the exposure and development.

That's true, but it's a joke compared to being able to directly tune the
black level & amptitude of RGB levels on an LCD panel or CRT.



--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

The Natural Philosopher wrote:
Bob Larter wrote:
The Natural Philosopher wrote:
wrote:
The Natural Philosopher wrote:

You would think so really, but going back to film photography,
there are
reasons why portraits were always shot on e.g. Konica, landscapes on
Agfa or Fuji, , and no one used Kodak at all professionally -
Except for
Kodachrome..

NT

Film is a whole nother business. You've got a lot less control over
its 'colour settings' than you have with a display screen, and ditto
re optical linearity. The issues with an LCD screen are quite
different.

well in the sense that they all use combinations of RGB (or CYMK) to
produce a 'full colour spectrum'and none succeed perfectly for all
applications, they are considerably identical, actually.

You can't tweak the colour response of film, you can with CRTs or LCDs.

You can actually.

Nothing like to the degree that you can with CRTs or LCDs.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

wrote:
William Sommerwerck wrote:
wrote in message
...
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.

You havent defined what you mean by a 'photographically useful
illuminant'

One of 5500-6500K, typically.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Arfa Daily wrote:
wrote in message
...
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, which is why I made
the point earlier that in general, LCD TVs are set correctly 'out of the
box'.

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, which was ever the
case when CRTs were set up to give whites which were either too warm or too
cold, even by a fraction. Maybe 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.

That's exactly correct. The colour temperature of the reference white
(ie; the WB) is vitally important for correct colour rendition. The eye
will adjust to an incorrect WB, but it will still be incorrect.

All 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 ?

It's just as likely that, as you said, a salesbunny wound up the colour
control to make the image "look better". Go knows that it's common
practice in showrooms.


--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

William Sommerwerck wrote:
The ability of most consumers to do more than make a mess is
very unlikely. Even someone like myself, having calibrated displays
for 30 years, can't do much to align a color management system
without a GOOD meter. I can get gray scale improved, but not really
accurate.

Does anyone make cheap-but-good instrumentation? I could justify a $500
investment.

(I can hear you laughing now.)

Not at all:
http://spyder.datacolor.com/product-mc-s2e.php

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

"Bob Larter" wrote in message
...
William Sommerwerck wrote:

The ability of most consumers to do more than make a mess is
very unlikely. Even someone like myself, having calibrated displays
for 30 years, can't do much to align a color management system
without a GOOD meter. I can get gray scale improved, but not really
accurate.

Does anyone make cheap-but-good instrumentation? I could justify
a $500 investment. (I can hear you laughing now.)

Not at all: http://spyder.datacolor.com/product-mc-s2e.php


And the Spyder will let me set up my Pioneer Kuro correctly? Because that's
what we were discussing.

I already have a huey, which did a decent job on my computer monitor.

"William Sommerwerck" wrote in message
...
This is simply not true. Every display has a color gamut that is
limited by the maximum saturation of its primaries. You can
produce any color within that gamut but not any outside.

Correct.


Even if every flesh tone is in that gamut, that does not mean that
you will get the right flesh tones for a given combination of RGB.
In order to do so, you must have the same spectrum in the
primaries that you have in the camera filters...

This bothers me. It might be true in a practical sense, but it's always
struck me as being theoretically wrong (mostly because of the extreme
overlap of the eye's blue and green receptors). I won't start an argument,
though, because, even if my intuition is correct, I don't have the
"science"
to back it up.




The overlap is caused by the shape of the standard observer curves and is
part of the very reason that using a narrow band RGB device may not produce
color properly. The CIE standard observer curves are precisely attempts at
modeling the response of the human visual system. For decades, cameras have
been calibrated to match them, and phosphors designed to do the same, to the
degree possible. Now, with narrow spectrum devices, we have to consider the
implications of those assumptions. It may be that in the future, we should
simplify the system and use a narrow band response in cameras and reproduce
the RGB in the same manner at the display. Then we can more easily predict
the output of RGB systems using a standard matrix.

Leonard

"William Sommerwerck" wrote in message
...
"Bob Larter" wrote in message
...
William Sommerwerck wrote:

The ability of most consumers to do more than make a mess is
very unlikely. Even someone like myself, having calibrated displays
for 30 years, can't do much to align a color management system
without a GOOD meter. I can get gray scale improved, but not really
accurate.

Does anyone make cheap-but-good instrumentation? I could justify
a $500 investment. (I can hear you laughing now.)

Not at all: http://spyder.datacolor.com/product-mc-s2e.php


And the Spyder will let me set up my Pioneer Kuro correctly? Because
that's
what we were discussing.

I already have a huey, which did a decent job on my computer monitor.



My experience with the spyder products and other tristimulus colorimeters
such as those from xrite and sencore (really just a version of the xrite
products) is that they are a poor choice for anything other than gray scale.
If you want to adjust a CMS properly, you need a spectrophotometer. The
minimum useful would be the i1 pro.

Leonard

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.

Thinking about this offline leads me to realise that there is a
fundamental difference between the operation of a slide and the
operation of an LCD display.

A slide consists of a series of coloured dots (CMY) mixed together in
such a way that they filter out some of the colour, and leave the rest.
A red dot will be produced where the G and B have been filtered out,
and only the R left.

An LCD consists of ADJACENT (not overlaid) coloured filters. So a red
dot is produced by having the B and G pixels opaque, and only the R one
(which always has no G or B) letting light through.

Andy

William Sommerwerck wrote:
"Bob Larter" wrote in message
...
William Sommerwerck wrote:

The ability of most consumers to do more than make a mess is
very unlikely. Even someone like myself, having calibrated displays
for 30 years, can't do much to align a color management system
without a GOOD meter. I can get gray scale improved, but not really
accurate.

Does anyone make cheap-but-good instrumentation? I could justify
a $500 investment. (I can hear you laughing now.)

Not at all: http://spyder.datacolor.com/product-mc-s2e.php


And the Spyder will let me set up my Pioneer Kuro correctly? Because that's
what we were discussing.

I already have a huey, which did a decent job on my computer monitor.

In that case, you might be able to rig up some way of using it on your
Pioneer.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

wrote:
Leonard Caillouet wrote:
wrote in message
...
Arfa Daily wrote:
wrote in message
...
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,
fwiw my main set does, and I'm sure its not unique. Generally though a
TV is a much lower quality animal than a monitor, and displays much
lower quality data.


which is why I made
the point earlier that in general, LCD TVs are set correctly 'out of the
box'.
because they can be. CRTs are more variable, and the circuits used to
drive them a lot less precise, partly because CRT sets are generally
older, and the sort of standards expected in monitors have only begun
crossing over to tvs in recent years.


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,
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 its nothing
but a taste matter


which was ever the
case when CRTs were set up to give whites which were either too warm or
too
cold, even by a fraction.
but thats down to historic reasons, customers never expected precise
colour temp, and screens were routinely set up by eye. The circuits
involved couldnt set themselves up the way a modern LCD set can, there
was normally no feedback on colour channels, just open loop CRT gun
drive on top of a massive dc offset, so the systems were inherently
variable. Plus the fact that CRT gamma was often way off from the real
world made it hard, or should I say impossible, to set such sets to
give a faithful reproduction in other respects anyway.


Maybe 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.


All 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
Its just a guess. In fact any desired flesh tone can be reproduced
using almost any colour temp backlight, certainly anything from 3,000K
to 10,000K. Think about the process, you've got 3 colour channels,
each of which has a given level of light from the backlight, which is
then attenuated to any desired degree by the LCD pixel.


NT

While this is true, it would be virtually impossible to get all colors right
with some arbitrary color backlight. You could get a subset right and get
all the others completely wrong.

Leonard

With each colour channel you've got everything available from
backlight output x LCD max down to backlight output x LCD minimum.
AFAIK that covers every flesh tone on this planet, unless one goes
down to 2000K backlight or some other very extreme value.

The problem with LCD monitors is they typically only have 6 bits (64
levels) of resolution for each colour channel, so you don't have a lot
of scope for tweaking the WB via the LUTs. Do it that way, & you'll lose
tonal detail, resulting in posterisation.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

And the Spyder will let me set up my Pioneer Kuro correctly?
Because that's what we were discussing.
I already have a huey, which did a decent job on my computer monitor.

In that case, you might be able to rig up some way of using it on your
Pioneer.

Uh-huh.

wrote:
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.

There's no such thing as a 5000K LCD display, sans backlight. Until you
put light through it, an LCD doesn't have a colour temperature at all.

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.

Yes, it does. It drastically reduces the number of transmission levels
available to the pixels of that colour, causing posterisation & colour
distortion. The more out of whack the colour temperature of the
backlight is in comparison to the desired colour temperature of the
image, the worse the problem will get.
Unlike CRTs, the transmission value of an LCD pixel isn't infinitely
variable, they only work in steps.


--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Dave Plowman (News) wrote:
In article ,
Arfa Daily 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.

Exactly. It's why CRTs are better than LCDs for editing photos, for example.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------