Origins of PAL: 1956 radio engeenering airticle from UK mag -- phase alternations (and effects) considered...

In article ,
(Alan) writes:

Indeed. Four years ago in the U.K., I had the amusement of watching
an old episode of Quincy M.E. -- a U.S. program.

The very saddest possibility would be seeing CSI without even the
POSSIBILITY of seeing it in HDTV. In that specific case, I believe
that CSI (the original version) is actually made to be a better
show because of HDTV and the nature of the graphics on the show.

Also, all too often, I had seen (this last week) that even shows
that are 16:9 in the US aren't provided as 16:9 in the UK.

Frankly, with a new 100Hz TV set, the perceivable detail and image
quality does appear to seem better than on a 50Hz TV set...

John

In article [email protected],
"Sal M. Onella" writes:

"Paul Ratcliffe" wrote in message
...



Indeed, and it is uncorrectable if it's a differential phase errro, which
is why NTSC is so crap.

"The pioneers take all the arrows."

Actually, in my recent visit to the UK, I saw more inaccurate color
in faces than I have recently seen in the US.

John

John S. Dyson wrote:

Also, all too often, I had seen (this last week) that even shows
that are 16:9 in the US aren't provided as 16:9 in the UK.

Frankly, with a new 100Hz TV set, the perceivable detail and image
quality does appear to seem better than on a 50Hz TV set...

It's not even as good, because interlace artifacts are exacerbated (I
had the opportunity to make side-by-side comparisons at The Sony Store
in Milan a few months ago). The only benefit is reduction of flicker
associated with 50hz.

However, even the 50hz flicker problem is minimal if a set is properly
calibrated and the white level kept low.

It would be much better in PAL countries to sell high-end TVs with
Faroudja circuits to convert the signal to 576p and then show the image
at 75hz -- which would eliminate both flicker and interlace artifacts.








C.

John S. Dyson wrote:

Like we had quadriphonic radio broadcasts in the seventies. I would guess
that more than 99% of broadcast TV in the US is 525 line.

Nowhere near 99%. Prime time is about half true HDTV. Prime time
is 1/8 of the day, so 1/2 of 1/8 is 1/16, which is 6%. There
are also HDTV broadcasts outside prime time, including much sports,
including at some time on Sunday as many as 10 different
HDTV broadcasts, one afternoon soap opera (yes, I know),
and Jay Leno, soon Letterman too.

During my recent visit to the UK (just returned today), I realized
that even our HDTV (16:9) shows are NOT necessarily shown in 16:9 and/or
PALPlus in UK.

Come to you senses, come to America, and look at our HDTV.

Your jaw will fall off.

PALPlus looks okay (on 100Hz TV), but it is far far far from HD. I had
also noticed that the 100Hz TV showed obtrusive scanlines (even small
screen, Loewe TV), yet I don't see a visible scanline on my own TV,
even displaying NTSC on the HDTV. Any kind of artifacting, including
visible scanlines, helps to confuse or distract the human vision system.

This would be because 576i (even at 100hz) is considerably fewer scan
lines than 1080i or 720p at 60hz.

OTOH, with Faroudja DCDi deinterlacing even 480p from NTSC sources
completely blows away anything I've seen from a PAL source.

The flicker still persists (on 50Hz TV sets), but the 100Hz display
(perhaps imperfect, however) makes the PAL video look generally better.
My travelling companion (a co-worker) initially thought I was very
wrong about the 'flickerfest' problem until I informed him that our
hotel (Aztec in Bristol) seemed to provide each of us with 100Hz TV sets.
Initially, I was somewhat worried about my reputation when I looked at my
first true UK TV set in 21yrs, and it took a few minutes (1-2minutes) for me
to realize that it was a 100Hz TV. Star Trek, Next Generation (even with
NTSC composite 60i post production), didn't really look bad. Apparently,
they took advantage of NTSC 3D combing to remove the NTSC artifacting,
and did a good quality conversion. To me, the TNG broadcasts looked
little different from pristine NTSC reception of the same thing using
my HDTV.

Perhaps the worst case that I saw was a transcoded King of Queens. It
looked horrendous, perhaps even worse than the early Dr Who looked
here. (Given that show is done in 24p, and that looked like a moderatly
current episode, then there is NO excuse for artifacting other than doing
something silly like
24p(original) -- 60i(US submaster) -- 50(i/p) (broadcast)-- 100i (tv)
There is almost NO excuse for using a 60i scan in the process.

Also, some morning news shows are done in PAL, and the conversion
to digital is done without 3D comb (there aren't any commodity PAL
3D combs, however a few SPECIALTY devices.) The color flashing even
on non moving subjects still persisted, even on the digital version.
In the US, the concept of providing a moderately high end, composite
`video analog capable TV set without a 3D comb would result in almost
a totally failed product.

Were you able to compare Sony and Loewe 100hz sets?







C.

John S. Dyson wrote:

PAL TV sets just cannot give an accurate green (period.) Claiming that
NTSC is perfect would be wrong, but it is amazing when you do an a-b
with a closer-to-NTSC phosphor gamut. On phosphor based displays, the gamut
issue is problematical with practical, safe, low cost phosphors. On
filter based designs, I suspect that there is more freedom.

Can you enlighten me as to which specific aspect of PAL encoding is
responsible for providing 'inaccurate color' ?

Actually, the fact that PAL isn't as completely decoded as NTSC
kind-of makes those color flashes more likely (which even appeared on
some apparently digital broadcasts due to BBC not using their cool
3D comb and/or not using component instead of composite in critical
parts of the infrastructure.) That kind of color flashing artifact
provides an essentially TOTAL FAILURE on the section of the scene.

Perception-wise, color on NORMAL scenes, assuming non-3D comb solvable
situations, NTSC and PAL aren't that different. As technology is improved
(e.g. motion prediction or equivalent is included to allow 3D combing
to work on PAL50), then NTSC decoding will also be improved. The
major hole in coming with 3D combs on NTSC is that the decoding drops
to the level of 2D comb on the portions of the scene that change too
much.

(The advantage of 3D comb isn't just related to color, but
the luma detail is also higher because of the elimination of the diagonal
detail problem -- essentially chopping off the diagonal detail at around
the chroma subcarrier frequency. Other, non color aspects of 3D combs is
off topic, however.)

It's no coincidence that the first NTSC consumer set with a 3D comb
filter, Sony's XBR100 (introduced nine years ago), was widely hailed as
the best consumer TV in history.

3D combs now are pretty well standard in America for higher end TVs.
I'd say they are mandatory if NTSC sources are to be rescaled
effectively to 480p, or higher.







C.

"Sal M. Onella" wrote in message
news:[email protected]

"J.Michael Davison" wrote in message
...

"Doug McDonald" wrote in message
...
But, of course, PAL was simply infeasible as a consumer
technology in 1950-1953 when color TV was developed ...
and we note, NOT developed by Europeans, who simply
adapted the ideas of the Americans (even, of course, SECAM,
which used a subcarrier and split luma-chroma rather than
actual RGB).
Eh !
ALL monochrome compatible colour TV systems use split luma-chroma with
the
chroma carried by a sub-carrier system.
Monochrome compatibility was the cornerstone of NTSC, PAL and SECAM so
black
and white TV owners were not denied a TV service. Frame sequential RGB
systems were not deemed to be compatible or practicable for that matter.
Mike Davison.

Trivial, perhaps: The US NASA used a color-wheel system for some of the
Apollo TV transmissions from the moon. I don't know if it was frame
sequential
or field sequential -- I thought field-sequential.

Correct. It was a sequential system on those later moonshots - you could see
that when there was significant movement. The single tube colour camera was
still in development so rotating filters in front of a vidicon type of tube
was the only way for size and weight if colour pictures from the moon were
wanted.
Mike D.

"John S. Dyson" wrote in message
...
snip
PAL TV sets just cannot give an accurate green (period.)
That must be bunk.
The mathematics for deriving the luminance and colour difference signals for
both the NTSC and PAL systems is the same only the onward encoding for
broadcast is different.

Can you enlighten me as to which specific aspect of PAL encoding is
responsible for providing 'inaccurate color' ?

I'd like an answer there as well.

Actually, the fact that PAL isn't as completely decoded as NTSC
kind-of makes those color flashes more likely (which even appeared on
some apparently digital broadcasts due to BBC not using their cool
3D comb and/or not using component instead of composite in critical
parts of the infrastructure.) That kind of color flashing artifact
provides an essentially TOTAL FAILURE on the section of the scene.

Perception-wise, color on NORMAL scenes, assuming non-3D comb solvable
situations, NTSC and PAL aren't that different. As technology is
improved
(e.g. motion prediction or equivalent is included to allow 3D combing
to work on PAL50), then NTSC decoding will also be improved. The
major hole in coming with 3D combs on NTSC is that the decoding drops
to the level of 2D comb on the portions of the scene that change too
much.

(The advantage of 3D comb isn't just related to color, but
the luma detail is also higher because of the elimination of the diagonal
detail problem -- essentially chopping off the diagonal detail at around
the chroma subcarrier frequency. Other, non color aspects of 3D combs is
off topic, however.)

No there's no answer there just a lot of waffle. Is there no deficiency
observed on off-air NTSC signals due to the unequal bandwidths of the I and
Q suppressed subcarriers in the NTSC transmission specification ? At least
in the UK PAL system I transmissions the U and V bandwidths are the same.
Mike D.

In article , John S. Dyson wrote:
PAL TV sets just cannot give an accurate green (period.)

Can you explain why not? I've seen plenty of colour bar signals encoded
and decoded through PAL and NTSC equipment, and there is nothing
special about the green one. The system treats green just as accurateky
as anything else. I've also watched plenty of programmes containing
green objects on a variety of professional monitors and domestic TV
sets using both PAL and NTSC encoding, and have never seen any
differences corresponding to the encoding system used.

Rod.

In article , John S. Dyson wrote:
Actually, in my recent visit to the UK, I saw more inaccurate color
in faces than I have recently seen in the US.

This has probably more to do with the way the pictures were lit and
shot, and the way the camera was adjusted, than anything to do with the
encoding system.

Rod.

In article ,
Roderick Stewart writes:
In article , John S. Dyson wrote:
PAL TV sets just cannot give an accurate green (period.)

Can you explain why not?

Look up the color gamut, and then recognize that 'grass green' is
much better reproduced with the original NTSC gamut.

Color bars are NOT an indicator of gamut, but are used to "tune-up"
a system.

John