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when is 720p not 720p?

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Anonymous
May 2, 2005 7:42:40 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

According to this slashdot thread, it's when your 720p LCD/DLP/LCOS TV
displays a 1080i signal by taking a single 540 line field from each 1080i
frame, ignoring the other field, and scaling it up to 720p. Apparently,
it takes less processor power to do this than to convert 1080i to 1080p
then scale that down to 720p.

So, when watching 1080i material on such a 720p HDTV, you're actually
watching it in SD.

http://hardware.slashdot.org/hardware/05/05/02/120227.s...

-- Mark --

http://staff.washington.edu/mrc
Science does not emerge from voting, party politics, or public debate.
Si vis pacem, para bellum.

More about : 720p 720p

Anonymous
May 3, 2005 2:12:49 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

Mark Crispin wrote:
> According to this slashdot thread, it's when your 720p LCD/DLP/LCOS TV
> displays a 1080i signal by taking a single 540 line field from each
> 1080i frame, ignoring the other field, and scaling it up to 720p.
> Apparently, it takes less processor power to do this than to convert
> 1080i to 1080p then scale that down to 720p.
>
> So, when watching 1080i material on such a 720p HDTV, you're actually
> watching it in SD.
>
> http://hardware.slashdot.org/hardware/05/05/02/120227.s...


So, someone makes an assertion, with absolutely no corroborating
evidence and it is taken as the gospel. Let hemos post some proof before
you take his assertion seriously. It just doesn't take all that much
computer power to properly rescale 1080i to 720p. That's not to say that
some display might do this conversion badly.

I presented this issue to someone who did image rescaling for a startup.
His reaction was "1080i to 720p is a yawn, try going the other way if
you want a challenge".

Matthew

--
Thermodynamics and/or Golf for dummies: There is a game
You can't win
You can't break even
You can't get out of the game
May 3, 2005 2:38:39 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

The source for this information is Tom Norton on the Guide To Home Theater
website. No matter how much we may hem and haw about it, the method for
converting 1080I transmissions to 720P is to capture only 540 lines of
resolution and "upgrade" to 720P. It was decided that it takes too much
horsepower to de-interlace 1080I and downconvert to 720P. The result is an
"upgraded" standard definition picture on a 720P television set.

Anybody ready to take the gaspipe?


"Matthew L. Martin" <nothere@notnow.never> wrote in message
news:117dnh6r4k6m5f@corp.supernews.com...
> Mark Crispin wrote:
> > According to this slashdot thread, it's when your 720p LCD/DLP/LCOS TV
> > displays a 1080i signal by taking a single 540 line field from each
> > 1080i frame, ignoring the other field, and scaling it up to 720p.
> > Apparently, it takes less processor power to do this than to convert
> > 1080i to 1080p then scale that down to 720p.
> >
> > So, when watching 1080i material on such a 720p HDTV, you're actually
> > watching it in SD.
> >
> >
http://hardware.slashdot.org/hardware/05/05/02/120227.s...
>
>
> So, someone makes an assertion, with absolutely no corroborating
> evidence and it is taken as the gospel. Let hemos post some proof before
> you take his assertion seriously. It just doesn't take all that much
> computer power to properly rescale 1080i to 720p. That's not to say that
> some display might do this conversion badly.
>
> I presented this issue to someone who did image rescaling for a startup.
> His reaction was "1080i to 720p is a yawn, try going the other way if
> you want a challenge".
>
> Matthew
>
> --
> Thermodynamics and/or Golf for dummies: There is a game
> You can't win
> You can't break even
> You can't get out of the game
Related resources
May 3, 2005 5:05:28 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

"Mark Crispin" <MRC@CAC.Washington.EDU> wrote in message
news:p ine.WNT.4.63.0505021538190.2240@Tomobiki-Cho.CAC.Washington.EDU...
> According to this slashdot thread, it's when your 720p LCD/DLP/LCOS TV
> displays a 1080i signal by taking a single 540 line field from each 1080i
> frame, ignoring the other field, and scaling it up to 720p. Apparently,
> it takes less processor power to do this than to convert 1080i to 1080p
> then scale that down to 720p.
>
> So, when watching 1080i material on such a 720p HDTV, you're actually
> watching it in SD.
>
> http://hardware.slashdot.org/hardware/05/05/02/120227.s...
>
> -- Mark --
>
Well, even if correct, you are still getting full 720p horizontal
resolution.

Richard.
Anonymous
May 3, 2005 11:09:59 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

So everyone does it this way? "The" method? Funny, I have never heard that
from any of the tech reps or training courses that I have attended. I'll
have to check it out, but de-interlacing has been a subject of much effort
in recent years and the "horsepower" is pretty common now. I suspect that
what we have here is someone who found that a particular manufacturer is
using only one field and discussed it as if every set does so. You might
want to check out your info before assuming that everything you read on the
internet is fact, or before applying it so broadly. My bet is that we find
few sets actually do so, and most of those are likely to be cheap ED sets
anyway.

Take that gaspipe, please, or learn to check things out before posting such
assumptions.

Leonard

"Stan" <ssum9160@adelphia.net> wrote in message
news:3LudnasttuqpeevfRVn-qA@adelphia.com...
> The source for this information is Tom Norton on the Guide To Home Theater
> website. No matter how much we may hem and haw about it, the method for
> converting 1080I transmissions to 720P is to capture only 540 lines of
> resolution and "upgrade" to 720P. It was decided that it takes too much
> horsepower to de-interlace 1080I and downconvert to 720P. The result is
an
> "upgraded" standard definition picture on a 720P television set.
>
> Anybody ready to take the gaspipe?
>
>
> "Matthew L. Martin" <nothere@notnow.never> wrote in message
> news:117dnh6r4k6m5f@corp.supernews.com...
> > Mark Crispin wrote:
> > > According to this slashdot thread, it's when your 720p LCD/DLP/LCOS TV
> > > displays a 1080i signal by taking a single 540 line field from each
> > > 1080i frame, ignoring the other field, and scaling it up to 720p.
> > > Apparently, it takes less processor power to do this than to convert
> > > 1080i to 1080p then scale that down to 720p.
> > >
> > > So, when watching 1080i material on such a 720p HDTV, you're actually
> > > watching it in SD.
> > >
> > >
>
http://hardware.slashdot.org/hardware/05/05/02/120227.s...
> >
> >
> > So, someone makes an assertion, with absolutely no corroborating
> > evidence and it is taken as the gospel. Let hemos post some proof before
> > you take his assertion seriously. It just doesn't take all that much
> > computer power to properly rescale 1080i to 720p. That's not to say that
> > some display might do this conversion badly.
> >
> > I presented this issue to someone who did image rescaling for a startup.
> > His reaction was "1080i to 720p is a yawn, try going the other way if
> > you want a challenge".
> >
> > Matthew
> >
> > --
> > Thermodynamics and/or Golf for dummies: There is a game
> > You can't win
> > You can't break even
> > You can't get out of the game
>
>
Anonymous
May 3, 2005 2:41:55 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Leonard Caillouet wrote:
> So everyone does it this way? "The" method? Funny, I have never heard that
> from any of the tech reps or training courses that I have attended. I'll
> have to check it out, but de-interlacing has been a subject of much effort
> in recent years and the "horsepower" is pretty common now. I suspect that
> what we have here is someone who found that a particular manufacturer is
> using only one field and discussed it as if every set does so. You might
> want to check out your info before assuming that everything you read on the
> internet is fact, or before applying it so broadly. My bet is that we find
> few sets actually do so, and most of those are likely to be cheap ED sets
> anyway.
>
> Take that gaspipe, please, or learn to check things out before posting such
> assumptions.
>

This is similar to the claim that DVD players (used to) convert
anamorphic content for display on 4:3 sets by simply dropping every
fourth line. I've yet to see this claim attached to any DVD player, much
less clearly proven.

I'm not saying that no DVD player has ever used that method of
conversion. It's possible. However, even in 1997 the cost of a bilinear
filter was in the noise. I seriously doubt that any major manufacturer
ever released a DVD player that simply dropped every fourth line.

--
Matthew

I'm a contractor. If you want an opinion, I'll sell you one.
Which one do you want?
Anonymous
May 3, 2005 2:45:37 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Not much of an upgrade, then? "Smearing" 540 lines of information across a
720 line display will not result in any increased detail/quality, as far as
I can imagine. So the only benefit remaining is getting rid of the flicker
from the interlacing, which may not be visible at all on some screens.

I'm loosing my faith in 720 line screens... better wait for true 1920x1080
resolution, I guess.
dOinK

"Stan" <ssum9160@adelphia.net> wrote in message
news:3LudnasttuqpeevfRVn-qA@adelphia.com...
> The source for this information is Tom Norton on the Guide To Home Theater
> website. No matter how much we may hem and haw about it, the method for
> converting 1080I transmissions to 720P is to capture only 540 lines of
> resolution and "upgrade" to 720P. It was decided that it takes too much
> horsepower to de-interlace 1080I and downconvert to 720P. The result is
> an
> "upgraded" standard definition picture on a 720P television set.
>
> Anybody ready to take the gaspipe?
>
>
> "Matthew L. Martin" <nothere@notnow.never> wrote in message
> news:117dnh6r4k6m5f@corp.supernews.com...
>> Mark Crispin wrote:
>> > According to this slashdot thread, it's when your 720p LCD/DLP/LCOS TV
>> > displays a 1080i signal by taking a single 540 line field from each
>> > 1080i frame, ignoring the other field, and scaling it up to 720p.
>> > Apparently, it takes less processor power to do this than to convert
>> > 1080i to 1080p then scale that down to 720p.
>> >
>> > So, when watching 1080i material on such a 720p HDTV, you're actually
>> > watching it in SD.
>> >
>> >
> http://hardware.slashdot.org/hardware/05/05/02/120227.s...
>>
>>
>> So, someone makes an assertion, with absolutely no corroborating
>> evidence and it is taken as the gospel. Let hemos post some proof before
>> you take his assertion seriously. It just doesn't take all that much
>> computer power to properly rescale 1080i to 720p. That's not to say that
>> some display might do this conversion badly.
>>
>> I presented this issue to someone who did image rescaling for a startup.
>> His reaction was "1080i to 720p is a yawn, try going the other way if
>> you want a challenge".
>>
>> Matthew
>>
>> --
>> Thermodynamics and/or Golf for dummies: There is a game
>> You can't win
>> You can't break even
>> You can't get out of the game
>
>
May 3, 2005 2:58:07 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

On Mon, 2 May 2005 15:42:40 -0700, Mark Crispin
<MRC@CAC.Washington.EDU> wrote:

>According to this slashdot thread, it's when your 720p LCD/DLP/LCOS TV
>displays a 1080i signal by taking a single 540 line field from each 1080i
>frame, ignoring the other field, and scaling it up to 720p.

Luckily my own eyes tell me different with my JVC D-ILA. There is no
way that 1080i broadcasts are 540 lines. I'd love to see proof
otherwise.
May 3, 2005 3:05:49 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

You will find the statement by Tim Norton at
http://www.guidetohometheater.com/news/042905hetjn/

The paragraph reads as follows:
"Since most TVs and projectors today operate at a native rate of 720p
(slightly different in the case of some flat panels), a 1080i
high-definition source must be converted to 720p for display. Silicon Optix
claimed that most TV manufacturers do this by using just one 540-line field
from each 1080i frame, scaling it up to 720p, because this requires much
less processing horsepower than deinterlacing 1080i to 1080p and then
scaling to 720p. I reported this technique first in my review of the InFocus
ScreenPlay 777. (So far I have not seen it mentioned in any other
publication.) This essentially limit's the resolution of such a source to
540p, which, technically, is not high definition. On the other hand, the
Realta HQV is said to first convert a 1080i source to 1080p, then
downconvert that to 720p."

Obviously, Silicon Optix should be challenged on what they have told Mr.
Norton.


"Matthew L. Martin" <nothere@notnow.never> wrote in message
news:117f3dkfs443ue0@corp.supernews.com...
> Leonard Caillouet wrote:
> > So everyone does it this way? "The" method? Funny, I have never heard
that
> > from any of the tech reps or training courses that I have attended.
I'll
> > have to check it out, but de-interlacing has been a subject of much
effort
> > in recent years and the "horsepower" is pretty common now. I suspect
that
> > what we have here is someone who found that a particular manufacturer is
> > using only one field and discussed it as if every set does so. You
might
> > want to check out your info before assuming that everything you read on
the
> > internet is fact, or before applying it so broadly. My bet is that we
find
> > few sets actually do so, and most of those are likely to be cheap ED
sets
> > anyway.
> >
> > Take that gaspipe, please, or learn to check things out before posting
such
> > assumptions.
> >
>
> This is similar to the claim that DVD players (used to) convert
> anamorphic content for display on 4:3 sets by simply dropping every
> fourth line. I've yet to see this claim attached to any DVD player, much
> less clearly proven.
>
> I'm not saying that no DVD player has ever used that method of
> conversion. It's possible. However, even in 1997 the cost of a bilinear
> filter was in the noise. I seriously doubt that any major manufacturer
> ever released a DVD player that simply dropped every fourth line.
>
> --
> Matthew
>
> I'm a contractor. If you want an opinion, I'll sell you one.
> Which one do you want?
Anonymous
May 3, 2005 4:47:47 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Ok so you bought that new LCD/DLP/LCOS TV.

Did you consider at that time that it did not have the ability to display
a 1080i TV program?


--
Korbin Dallas
The name was changed to protect the guilty.
Anonymous
May 3, 2005 4:57:10 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Stan wrote:
> You will find the statement by Tim Norton at
> http://www.guidetohometheater.com/news/042905hetjn/
>
> The paragraph reads as follows:
> "Since most TVs and projectors today operate at a native rate of 720p
> (slightly different in the case of some flat panels), a 1080i
> high-definition source must be converted to 720p for display. Silicon Optix
> claimed that most TV manufacturers do this by using just one 540-line field
> from each 1080i frame, scaling it up to 720p, because this requires much
> less processing horsepower than deinterlacing 1080i to 1080p and then
> scaling to 720p. I reported this technique first in my review of the InFocus
> ScreenPlay 777. (So far I have not seen it mentioned in any other
> publication.)

I wonder why that might be?

> This essentially limit's the resolution of such a source to
> 540p, which, technically, is not high definition. On the other hand, the
> Realta HQV is said to first convert a 1080i source to 1080p, then
> downconvert that to 720p."

There is no reason whatsoever to convert to 1080p first. The two
alternate fields of 1080i can be converted directly to 720p.

> Obviously, Silicon Optix should be challenged on what they have told Mr.
> Norton.
>

Of course they should.

--
Matthew

I'm a contractor. If you want an opinion, I'll sell you one.
Which one do you want?
May 3, 2005 5:08:07 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Matthew, are you saying that you choose to believe that Silicon Optix is in
error?


"Matthew L. Martin" <nothere@notnow.never> wrote in message
news:117fbba3dgbq88c@corp.supernews.com...
> Stan wrote:
> > You will find the statement by Tim Norton at
> > http://www.guidetohometheater.com/news/042905hetjn/
> >
> > The paragraph reads as follows:
> > "Since most TVs and projectors today operate at a native rate of 720p
> > (slightly different in the case of some flat panels), a 1080i
> > high-definition source must be converted to 720p for display. Silicon
Optix
> > claimed that most TV manufacturers do this by using just one 540-line
field
> > from each 1080i frame, scaling it up to 720p, because this requires much
> > less processing horsepower than deinterlacing 1080i to 1080p and then
> > scaling to 720p. I reported this technique first in my review of the
InFocus
> > ScreenPlay 777. (So far I have not seen it mentioned in any other
> > publication.)
>
> I wonder why that might be?
>
> > This essentially limit's the resolution of such a source to
> > 540p, which, technically, is not high definition. On the other hand, the
> > Realta HQV is said to first convert a 1080i source to 1080p, then
> > downconvert that to 720p."
>
> There is no reason whatsoever to convert to 1080p first. The two
> alternate fields of 1080i can be converted directly to 720p.
>
> > Obviously, Silicon Optix should be challenged on what they have told Mr.
> > Norton.
> >
>
> Of course they should.
>
> --
> Matthew
>
> I'm a contractor. If you want an opinion, I'll sell you one.
> Which one do you want?
Anonymous
May 3, 2005 5:09:49 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Stan wrote:
> Matthew, are you saying that you choose to believe that Silicon Optix is in
> error?
>

Are you saying that you choose to believe whatever they say without proof?

--
Matthew

I'm a contractor. If you want an opinion, I'll sell you one.
Which one do you want?
Anonymous
May 3, 2005 5:13:09 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

"dOinK" <doinkx@on-my-tan-line.no> wrote in message
news:D 57dni$pk2$1@bat-news01.osl.basefarm.net...
> Not much of an upgrade, then? "Smearing" 540 lines of information across a
> 720 line display will not result in any increased detail/quality, as far
> as I can imagine. So the only benefit remaining is getting rid of the
> flicker from the interlacing, which may not be visible at all on some
> screens.
>
> I'm loosing my faith in 720 line screens... better wait for true 1920x1080
> resolution, I guess.
> dOinK
>
what-ev-er

....I have a 720p native set, and it is absolutely stunning on the HD
channels with my STB set to 720p OR 1080i...
May 3, 2005 5:28:26 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

I'm not saying ANYTHING. I was just wondering if you would clarify your
comments. This whole thing is going to take time to shake out.


"Matthew L. Martin" <nothere@notnow.never> wrote in message
news:117fc2ukrs1qbc9@corp.supernews.com...
> Stan wrote:
> > Matthew, are you saying that you choose to believe that Silicon Optix is
in
> > error?
> >
>
> Are you saying that you choose to believe whatever they say without proof?
>
> --
> Matthew
>
> I'm a contractor. If you want an opinion, I'll sell you one.
> Which one do you want?
Anonymous
May 3, 2005 5:34:41 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Stan wrote:
> Matthew, are you saying that you choose to believe that Silicon Optix is in
> error?
>

What comment would you like clarified?

--
Matthew

I'm a contractor. If you want an opinion, I'll sell you one.
Which one do you want?
Anonymous
May 3, 2005 9:51:20 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Mark Crispin wrote:
> According to this slashdot thread, it's when your 720p LCD/DLP/LCOS TV
> displays a 1080i signal by taking a single 540 line field from each
> 1080i frame, ignoring the other field, and scaling it up to 720p.
> Apparently, it takes less processor power to do this than to convert
> 1080i to 1080p then scale that down to 720p.
>
> So, when watching 1080i material on such a 720p HDTV, you're actually
> watching it in SD.
>
> http://hardware.slashdot.org/hardware/05/05/02/120227.s...
>
>
> -- Mark --
>
> http://staff.washington.edu/mrc
> Science does not emerge from voting, party politics, or public debate.
> Si vis pacem, para bellum.

This was posted on OpenDTV by Jeroen Stessen in answer to my query on
the subject.

Hi,

Bob Miller wrote:
http://hardware.slashdot.org/hardware/05/05/02/120227.s...

>> This thread says that received 1080i on a native 720P will see the
>> conversion of a single 540i frame into 720P by 1980.


I should hope not !
Most if not all de-interlacers for HDTV are "motion adaptive".
On still images, and on 24p or 30p film mode, they will weave two
540i fields into one 1080p frame. No problem at all. If you consider
that much material is originated from 24p film, or from 24p video
productions, then that is really 1080@24p transported as 1080@30i.
Perfect reconstruction of the 1080p is then trivially easy, at the
cost of one or two field memories in the receiver.

It is only with moving images in (50i/60i) video mode that there is
a fundamental problem for de-interlacers. There will no longer be
two fields from the same motion phase, so weaving does not work
anymore. Then intra-field interpolation, indeed from 540 lines, is
the easiest (but incorrect) solution. Motion adaptive de-interlacers
will necessarily switch to intra-field mode. The smarter MA designs
make such decision (between still/film and video mode) for each
individual pixel, preserving weaving e.g. for still backgrounds.

A yet better solution, which we don't typically see for HDTV, is
based on application of the "Generalized Sampling Theorem". This
says that any two sets of samples, they don't have to be spaced
evenly as long as they don't coincide exactly, can be used for
reconstructing the original signal at the double Nyquist bandwidth.
With the use of motion vectors a "motion compensated" de-interlacer
can get the missing lines from previous frames, at least if the
vertical component of the motion is not near a "critical speed".

(A vertical motion of 2N+1 lines per field period reduces a 1080i
grid to a real 540p grid, it makes the two sets of samples coincide
and thus it makes de-interlacing and reconstruction of the full
vertical resolution according to the GST fundamentally impossible.)


>> How does this impact what we you were discussing about
>> 1080p>480P>720P?


Not. We weren't discussing 1080i->1080p conversion, and it will
only go wrong for moving images in video mode, which are can be
largely avoided by choosing 720p for difficult (sports) programs.
We should have some faith in today's decent de-interlacers.


>> How would that 720P compare to 720P converted in the former way
>> from 1080i? How would 640 x 480P compare to 1920 x 540i?


Well... using only half the lines from a sharp 1080 line image
implies a serious aliasing problem. Re-sampling is not going to
make that aliasing go away. On the contrary, it can make it
forever impossible to reduce the al
Anonymous
May 3, 2005 9:54:38 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Mark Crispin wrote:
> According to this slashdot thread, it's when your 720p LCD/DLP/LCOS TV
> displays a 1080i signal by taking a single 540 line field from each
> 1080i frame, ignoring the other field, and scaling it up to 720p.
> Apparently, it takes less processor power to do this than to convert
> 1080i to 1080p then scale that down to 720p.
>
> So, when watching 1080i material on such a 720p HDTV, you're actually
> watching it in SD.
>
> http://hardware.slashdot.org/hardware/05/05/02/120227.s...
>
>
> -- Mark --
>
> http://staff.washington.edu/mrc
> Science does not emerge from voting, party politics, or public debate.
> Si vis pacem, para bellum.

This was posted on OpenDTV by Jeroen Stessen in answer to my query on
the subject.

Hi,

Bob Miller wrote:
http://hardware.slashdot.org/hardware/05/05/02/120227.s...

>> This thread says that received 1080i on a native 720P will see the
>> conversion of a single 540i frame into 720P by 1980.


I should hope not !
Most if not all de-interlacers for HDTV are "motion adaptive".
On still images, and on 24p or 30p film mode, they will weave two
540i fields into one 1080p frame. No problem at all. If you consider
that much material is originated from 24p film, or from 24p video
productions, then that is really 1080@24p transported as 1080@30i.
Perfect reconstruction of the 1080p is then trivially easy, at the
cost of one or two field memories in the receiver.

It is only with moving images in (50i/60i) video mode that there is
a fundamental problem for de-interlacers. There will no longer be
two fields from the same motion phase, so weaving does not work
anymore. Then intra-field interpolation, indeed from 540 lines, is
the easiest (but incorrect) solution. Motion adaptive de-interlacers
will necessarily switch to intra-field mode. The smarter MA designs
make such decision (between still/film and video mode) for each
individual pixel, preserving weaving e.g. for still backgrounds.

A yet better solution, which we don't typically see for HDTV, is
based on application of the "Generalized Sampling Theorem". This
says that any two sets of samples, they don't have to be spaced
evenly as long as they don't coincide exactly, can be used for
reconstructing the original signal at the double Nyquist bandwidth.
With the use of motion vectors a "motion compensated" de-interlacer
can get the missing lines from previous frames, at least if the
vertical component of the motion is not near a "critical speed".

(A vertical motion of 2N+1 lines per field period reduces a 1080i
grid to a real 540p grid, it makes the two sets of samples coincide
and thus it makes de-interlacing and reconstruction of the full
vertical resolution according to the GST fundamentally impossible.)


>> How does this impact what we you were discussing about
>> 1080p>480P>720P?


Not. We weren't discussing 1080i->1080p conversion, and it will
only go wrong for moving images in video mode, which are can be
largely avoided by choosing 720p for difficult (sports) programs.
We should have some faith in today's decent de-interlacers.


>> How would that 720P compare to 720P converted in the former way
>> from 1080i? How would 640 x 480P compare to 1920 x 540i?


Well... using only half the lines from a sharp 1080 line image
implies a serious aliasing problem. Re-sampling is not going to
make that aliasing go away. On the contrary, it can make it
forever impossible to reduce the aliasing by proper de-interlacing.
So it would be a bad idea to apply scaling to an improperly de-
interlaced image, which is of course why all decent scaler ICs
contain also a decent de-interlacer (at least MA) that can do a
proper weaving of matching fields in film- or still image mode.
The "DCDi" type of de-interlacer pioneered by Faroudja (who later
seems to have denied its effectiveness, very strange) does already
a good enough job for most applications. So don't worry, the
statement on slashdot is a distortion of the truth.

Regards,
-- Jeroen
Anonymous
May 3, 2005 9:54:39 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Bob Miller wrote:
> So don't worry, the
> statement on slashdot is a distortion of the truth.
>
> Regards,
> -- Jeroen

Thank you for an informative, useful and on topic post.

--
Matthew

I'm a contractor. If you want an opinion, I'll sell you one.
Which one do you want?
Anonymous
May 4, 2005 2:01:47 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

On Tue, 3 May 2005, Matthew L. Martin wrote:
> Bob Miller wrote:
> Thank you for an informative, useful and on topic post.

I echo this sentiment. Bob came up with useful information here.

Since my TV is 1080i, the question of 1080i conversion to 720p doesn't
affect me directly. So, I was just passing on what seemed to be alarming
news. I'm glad to hear that it's a false alarm.

-- Mark --

http://staff.washington.edu/mrc
Science does not emerge from voting, party politics, or public debate.
Si vis pacem, para bellum.
May 4, 2005 3:29:59 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

On Mon, 2 May 2005 22:38:39 -0400, "Stan" <ssum9160@adelphia.net>
wrote:

>The source for this information is Tom Norton on the Guide To Home Theater
>website. No matter how much we may hem and haw about it, the method for
>converting 1080I transmissions to 720P is to capture only 540 lines of
>resolution and "upgrade" to 720P. It was decided that it takes too much
>horsepower to de-interlace 1080I and downconvert to 720P. The result is an
>"upgraded" standard definition picture on a 720P television set.
>

Doesn't this depend on the chip set used?

I look at the output of the OTA ATSC ( sir T 351 decoder on a 720
syntax olevia 720p monitor), and they are definately better than SD
May 4, 2005 5:49:42 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

I don't know, yet, that this is a false alarm or not. Methinks the jury is
still out.


"Mark Crispin" <MRC@CAC.Washington.EDU> wrote in message
news:p ine.WNT.4.63.0505040955370.3292@Shimo-Tomobiki.panda.com...
> On Tue, 3 May 2005, Matthew L. Martin wrote:
> > Bob Miller wrote:
> > Thank you for an informative, useful and on topic post.
>
> I echo this sentiment. Bob came up with useful information here.
>
> Since my TV is 1080i, the question of 1080i conversion to 720p doesn't
> affect me directly. So, I was just passing on what seemed to be alarming
> news. I'm glad to hear that it's a false alarm.
>
> -- Mark --
>
> http://staff.washington.edu/mrc
> Science does not emerge from voting, party politics, or public debate.
> Si vis pacem, para bellum.
Anonymous
May 5, 2005 12:24:10 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

george1234 wrote:
> On Mon, 2 May 2005 22:38:39 -0400, "Stan" <ssum9160@adelphia.net>
> wrote:
>
>
>>The source for this information is Tom Norton on the Guide To Home Theater
>>website. No matter how much we may hem and haw about it, the method for
>>converting 1080I transmissions to 720P is to capture only 540 lines of
>>resolution and "upgrade" to 720P. It was decided that it takes too much
>>horsepower to de-interlace 1080I and downconvert to 720P. The result is an
>>"upgraded" standard definition picture on a 720P television set.
>>
>
>
> Doesn't this depend on the chip set used?

Of course it does.

> I look at the output of the OTA ATSC ( sir T 351 decoder on a 720
> syntax olevia 720p monitor), and they are definately better than SD
>

Then it probably is.

Matthew

--
Thermodynamics and/or Golf for dummies: There is a game
You can't win
You can't break even
You can't get out of the game
Anonymous
May 5, 2005 5:07:17 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

"Korbin Dallas" <korbindallas@dodgeit.com> wrote in message
news:p an.2005.05.03.12.47.27.664946@dodgeit.com...
> Ok so you bought that new LCD/DLP/LCOS TV.
>
> Did you consider at that time that it did not have the ability to display
> a 1080i TV program?

Ok, so you bought that new widescreen CRT TV.

Did you consider at that time that it did not have the ability to display
a 720p TV program?

....

It goes both ways...
Anonymous
May 5, 2005 10:50:22 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

"Matthew Vaughan" <matt-no-spam-109@NOSPAM.hotmail.com> wrote in message
news:9leee.563$T3.2967@typhoon.sonic.net...
>
> "Korbin Dallas" <korbindallas@dodgeit.com> wrote in message
> news:p an.2005.05.03.12.47.27.664946@dodgeit.com...
> > Ok so you bought that new LCD/DLP/LCOS TV.
> >
> > Did you consider at that time that it did not have the ability to
display
> > a 1080i TV program?
>
> Ok, so you bought that new widescreen CRT TV.
>
> Did you consider at that time that it did not have the ability to display
> a 720p TV program?
>
> ...
>
> It goes both ways...

And both statements are wrong. Most sets can display both 720p and 1080i
programming. They will have to convert to one or the other that is their
native format, but they will display the program. Why must you post
statements that are confusing to those who do not understand the technology.
It sounds like both of you are trying to either mislead people or be
smart-asses who are trying to prove that they know something that the rest
of us don't. The fact is that this thread has served no purpose but to
increase confusion about standards. If you have a point to make, make it
clearly. We get enough half-truths and skewed perspectives on this group
already. There is no need to make it worse.

Each set will have a native display mode (or maybe two if it is a CRT based
set with multiple scan rates) that it will convert programs sources in other
modes to. Most HD sources such as STBs will convert anyway, so few people
have to worry about not being able to view a particular resolution program.
Some sets have not converted 720P, but this is not significant if an
external source does so.

You will not see every resolution in its native form on any display except a
multisync CRT computer monitor with 16:9 aspect ratio. You will, however,
be able to see all HD formats on most HD installations these days. It is
certainly important to make sure you understand what conversions and native
display you will be watching before you buy. Obviously, you want the best
conversion possible, and if you were to be watching primarily one resolution
program, it would be preferable to have a display that did not have to do
any conversion to view it. The fact is that format conversion has improve
considerably and is not as significant a matter as it was even a couple of
years ago, at least on the better quality products.

Look at the pix that you will be watching before you buy and understand it.
Don't pay attention to alarmist postings.

Leonard
Anonymous
May 9, 2005 4:56:59 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

"Leonard Caillouet" <no@no.com> wrote in message
news:SZmee.504$2J6.6@lakeread06...
>
> And both statements are wrong. Most sets can display both 720p and 1080i
> programming. They will have to convert to one or the other that is their
> native format, but they will display the program. Why must you post
> statements that are confusing to those who do not understand the
> technology.
> It sounds like both of you are trying to either mislead people or be
> smart-asses who are trying to prove that they know something that the rest
> of us don't. The fact is that this thread has served no purpose but to
> increase confusion about standards. If you have a point to make, make it
> clearly. We get enough half-truths and skewed perspectives on this group
> already. There is no need to make it worse.

Hey, if the standards and technology weren't confusing, there wouldn't be
much we all could do to confuse people. HDTV was designed confusing. I
didn't make it that way. If people are confused, then it's because of how
the whole HDTV system was set up, which is to say, a confusing mess.

And I'm pretty sure that what was being referred to was displaying a signal
at its maximum possible quality (and if high quality isn't a concern, then
why make such a fuss over "high definition" in the first place? Besides,
getting the best possible quality is the least people should be able to
expect when spending $5000 on a TV). Since that was the whole point of the
thread, I'd expect most people reading the thread would have figured that
out.
!