Sign in with
Sign up | Sign in
Your question

High Def TV's minimal display

Last response: in Home Theatre
Share
June 13, 2005 9:55:18 PM

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

Why do some TVs and monitors say they are High Def when they don't have
the proper number of vertical lines. For instance, they have a 1024 X
768 display but high def must be at least 1280 x 720, according to the
specs. Or am I wrong?

How do these displays show the picture? Do they delete some vertical
lines or what?

I've noticed this with some plasma TV and monitors from big name companies.
Anonymous
a b C Monitor
June 13, 2005 11:07:32 PM

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

tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
> Why do some TVs and monitors say they are High Def when they don't have
> the proper number of vertical lines. For instance, they have a 1024 X
> 768 display but high def must be at least 1280 x 720, according to the
> specs.

There aren't technically any "rules" for high definition displays, but
the members of the Consumer Electronics Association (CEA) agreed that they
would advertise displays as follows:

For 16x9 displays:
- At least 720 progressive scan lines: HD
- At least 1080 interlaced scan lines: HD

For 4:3 displays
- At least 540 progressive scan lines in the 16x9 area and a total of
at least 720 progressive scan lines: HD
- At least 810 interlaced scan lines in the 16x9 area and a total of
at least 1080 interlaced scan lines: HD

Notice the lack of any horizontal resolution in these standards? So,
a display with a resolution of 1x720 progressive *could* be advertised
as HD.

--
Jeff Rife |
| http://www.nabs.net/Cartoons/OverTheHedge/Chainsaw.gif
June 13, 2005 11:41:33 PM

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

Jeff Rife wrote:

> tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
>
>>Why do some TVs and monitors say they are High Def when they don't have
>>the proper number of vertical lines. For instance, they have a 1024 X
>>768 display but high def must be at least 1280 x 720, according to the
>>specs.
>
>
> There aren't technically any "rules" for high definition displays, but
> the members of the Consumer Electronics Association (CEA) agreed that they
> would advertise displays as follows:
>
> For 16x9 displays:
> - At least 720 progressive scan lines: HD
> - At least 1080 interlaced scan lines: HD
>
> For 4:3 displays
> - At least 540 progressive scan lines in the 16x9 area and a total of
> at least 720 progressive scan lines: HD
> - At least 810 interlaced scan lines in the 16x9 area and a total of
> at least 1080 interlaced scan lines: HD
>
> Notice the lack of any horizontal resolution in these standards? So,
> a display with a resolution of 1x720 progressive *could* be advertised
> as HD.
>
So how do they handle the fact that they can't show all of the vertical
lines?
Related resources
Anonymous
a b C Monitor
June 14, 2005 1:52:44 AM

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

tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
> So how do they handle the fact that they can't show all of the vertical
> lines?

Because they can? A 1024x768 16x9 display with progressive scanning fits the
following category:

- At least 720 progressive scan lines: HD

That's all the CEA agreement says they need to advertise "HD".

Otherwise, you'd get into a million nitpicky arguments, like even though
1080i displays have more than enough lines to handle 720p, they aren't
progressive, so the image is degraded in quality.

--
Jeff Rife |
| http://www.nabs.net/Cartoons/RhymesWithOrange/Recycling...
June 14, 2005 3:18:06 AM

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

Jeff Rife wrote:
> tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
>
>>Why do some TVs and monitors say they are High Def when they don't have
>>the proper number of vertical lines. For instance, they have a 1024 X
>>768 display but high def must be at least 1280 x 720, according to the
>>specs.
>
>
> There aren't technically any "rules" for high definition displays, but
> the members of the Consumer Electronics Association (CEA) agreed that they
> would advertise displays as follows:
>
> For 16x9 displays:
> - At least 720 progressive scan lines: HD
> - At least 1080 interlaced scan lines: HD
>
> For 4:3 displays
> - At least 540 progressive scan lines in the 16x9 area and a total of
> at least 720 progressive scan lines: HD
> - At least 810 interlaced scan lines in the 16x9 area and a total of
> at least 1080 interlaced scan lines: HD
>
> Notice the lack of any horizontal resolution in these standards? So,
> a display with a resolution of 1x720 progressive *could* be advertised
> as HD.
>
You're half right.
In addition to the 720p and 1080i scan line spec, CEA literature and
advertising directives ALSO provides for the minimum # of pixels to
qualify as "high definition" : 900,000 to 2.1 million pixels.
So your assertion that 1x720 could be advertised as HD is dead wrong.
Check it out at:
http://www.ce.org/shared_files/resources/DTV_Tip_Sheet....
Anonymous
a b C Monitor
June 14, 2005 5:59:42 AM

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

Curmudgeon (curmudgeon@buzzoff.net) wrote in alt.tv.tech.hdtv:
> In addition to the 720p and 1080i scan line spec, CEA literature and
> advertising directives ALSO provides for the minimum # of pixels to
> qualify as "high definition" : 900,000 to 2.1 million pixels.
> So your assertion that 1x720 could be advertised as HD is dead wrong.
> Check it out at:
> http://www.ce.org/shared_files/resources/DTV_Tip_Sheet....

That's new...it was created last November. I hadn't been back to the CEA
site since they first created the definitions nearly 3 years ago.

Still, they aren't punishing the companies that advertise 786,432 pixel
displays (1024x768) as HD, so I think there's a lot of slop in the pixel
count part.

--
Jeff Rife |
| http://www.nabs.net/Cartoons/Dilbert/LoveRanking.jpg
June 14, 2005 8:38:00 PM

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

Jeff Rife wrote:

> tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
>
>>So how do they handle the fact that they can't show all of the vertical
>>lines?
>
>
> Because they can?

But my question is, what do they do with the vertical lines they cannot
show? Do they drop them off or do they use some software to somehow
squeeze the info onto the available pixels or what?
I understand what you are saying, that technically they can say that but
if the screen was 900X768, what would they do to show all of the info,
or would they chop it off?


A 1024x768 16x9 display with progressive scanning fits the
> following category:
>
> - At least 720 progressive scan lines: HD
>
> That's all the CEA agreement says they need to advertise "HD".
>
> Otherwise, you'd get into a million nitpicky arguments, like even though
> 1080i displays have more than enough lines to handle 720p, they aren't
> progressive, so the image is degraded in quality.
>
Anonymous
a b C Monitor
June 14, 2005 11:59:23 PM

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

<tim@nocomment.com> wrote in message
news:jrCdnbEvlsq43TLfRVn-tg@rogers.com...


> But my question is, what do they do with the vertical lines they cannot
> show? Do they drop them off or do they use some software to somehow
> squeeze the info onto the available pixels or what?
> I understand what you are saying, that technically they can say that but
> if the screen was 900X768, what would they do to show all of the info, or
> would they chop it off?

The issue is not the "vertical" lines (which actually go from side to side
and there are either 720 or 1080 of them from top to bottom)... the issue is
horizontal resolution (which would require 1920 pixels for a full 1080i
display).

Very few sets of any technology can display 1920 pixels of horizontal
resolution - most CRT RP sets top out at 1600 lines or so and most LCD/PDP's
have only 1300 or so.

The CRT based sets essentially blur the extra resolution so there is a
smooth transition between the colors. The LCD/PDP's typically throw away
lines throughout the picture to get down to the number they have.
Anonymous
a b C Monitor
June 15, 2005 12:11:00 AM

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

tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
> But my question is, what do they do with the vertical lines they cannot
> show? Do they drop them off or do they use some software to somehow
> squeeze the info onto the available pixels or what?

Do you have a digital camera? Can you take a 2000x1500 photo with it?
Can you view it on your PC monitor? Is your PC monitor resolution less
than 2000x1500?

Maybe a 1024x768 HDTV does the same thing with a 1920x1080 picture?

Was that really so hard to figure out?

--
Jeff Rife | "I feel the need...the need for
| expeditious velocity"
|
| -- Brain
June 15, 2005 1:13:42 AM

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

Jeff Rife wrote:

> tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
>
>>But my question is, what do they do with the vertical lines they cannot
>>show? Do they drop them off or do they use some software to somehow
>>squeeze the info onto the available pixels or what?
>
>
> Do you have a digital camera? Can you take a 2000x1500 photo with it?
> Can you view it on your PC monitor? Is your PC monitor resolution less
> than 2000x1500?
>
> Maybe a 1024x768 HDTV does the same thing with a 1920x1080 picture?
>
> Was that really so hard to figure out?
>

Well, a lot of things CAN be done. I was asking what WAS being done.

OK?
June 15, 2005 1:42:23 AM

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

Randy Sweeney wrote:

> <tim@nocomment.com> wrote in message
> news:jrCdnbEvlsq43TLfRVn-tg@rogers.com...
>
>
>
>>But my question is, what do they do with the vertical lines they cannot
>>show? Do they drop them off or do they use some software to somehow
>>squeeze the info onto the available pixels or what?
>>I understand what you are saying, that technically they can say that but
>>if the screen was 900X768, what would they do to show all of the info, or
>>would they chop it off?
>
>
> The issue is not the "vertical" lines (which actually go from side to side
> and there are either 720 or 1080 of them from top to bottom)... the issue is
> horizontal resolution (which would require 1920 pixels for a full 1080i
> display).

Are you sure vertical lines go from side to side or is that vertical
resolution?

http://www.audiovideo101.com/dictionary/dictionary.asp?...

....Six ultimate quality forms of the digital television standard adopted
for the United States featuring AC-3 digital surround sound, a wide
aspect ratio screen (16:9), and a high-resolution picture capable of
interlaced video with 1,080 horizontal lines (vertical resolution) by
1,920 vertical lines (horizontal resolution) at 24, 30 and 60 Hz refresh
rate and progressive video at 720 horizontal lines by 1,280 vertical
lines with refresh rates at 24, 30 and 60 Hz. The higher resolution,
interlaced format presents 2,073,600 individual picture elements or
pixels for each frame, and the lower resolution, progressive format
presents 921,600 individual picture elements...

>
> Very few sets of any technology can display 1920 pixels of horizontal
> resolution - most CRT RP sets top out at 1600 lines or so and most LCD/PDP's
> have only 1300 or so.
>
> The CRT based sets essentially blur the extra resolution so there is a
> smooth transition between the colors. The LCD/PDP's typically throw away
> lines throughout the picture to get down to the number they have.
>
>
Anonymous
a b C Monitor
June 15, 2005 3:21:36 AM

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

tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
> Well, a lot of things CAN be done. I was asking what WAS being done.

The old line "there are no stupid questions" is a lie.

Do you really think that a 1024x768 display is just throwing away all
the pixels outside of the center of a 1920x1080 transmission?

Every display scales the input to fit the native resolution.

--
Jeff Rife |
| http://www.nabs.net/Cartoons/OverTheHedge/Chainsaw.gif
June 15, 2005 9:12:49 PM

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

Jeff Rife wrote:

> tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
>
>>Well, a lot of things CAN be done. I was asking what WAS being done.
>
>
> The old line "there are no stupid questions" is a lie.
>
> Do you really think that a 1024x768 display is just throwing away all
> the pixels outside of the center of a 1920x1080 transmission?
>
> Every display scales the input to fit the native resolution.
>

I realize there is upconverting and downconverting. I would think that
by scaling the picture when it is not necessary, you would naturally
incur some distortion which, as I understand it, is not a good thing.
I guess you feel adding distortion unnecessarily is OK.
Anonymous
a b C Monitor
June 15, 2005 10:22:14 PM

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

On Tue, 14 Jun 2005 19:59:23 -0400, "Randy Sweeney"
<DockScience@yahoo.com> wrote:

>
><tim@nocomment.com> wrote in message
>news:jrCdnbEvlsq43TLfRVn-tg@rogers.com...
>
>
>> But my question is, what do they do with the vertical lines they cannot
>> show? Do they drop them off or do they use some software to somehow
>> squeeze the info onto the available pixels or what?
>> I understand what you are saying, that technically they can say that but
>> if the screen was 900X768, what would they do to show all of the info, or
>> would they chop it off?
>
>The issue is not the "vertical" lines (which actually go from side to side
>and there are either 720 or 1080 of them from top to bottom)... the issue is
>horizontal resolution (which would require 1920 pixels for a full 1080i
>display).
>
>Very few sets of any technology can display 1920 pixels of horizontal
>resolution - most CRT RP sets top out at 1600 lines or so and most LCD/PDP's
>have only 1300 or so.
>
>The CRT based sets essentially blur the extra resolution so there is a
>smooth transition between the colors. The LCD/PDP's typically throw away
>lines throughout the picture to get down to the number they have.
>

LOL. Yeah, but be sure and buy any HDTV as ED plasmas aren't good
enough for pigs.
Anonymous
a b C Monitor
June 16, 2005 2:05:46 PM

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

tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
> I realize there is upconverting and downconverting. I would think that
> by scaling the picture when it is not necessary, you would naturally
> incur some distortion which, as I understand it, is not a good thing.

First, for a fixed-pixel display, there is only one resolution where you
don't have to scale the input signal: the native resolution.

So, a 1280x720 display will scale all other signals to fit. Likewise, a
1920x1080 display will scale all other signals to fit. There is no way
around this with a fixed-pixel display.

> I guess you feel adding distortion unnecessarily is OK.

Second, there is no need to introduce "distortion" when scaling.

A good scaler will do the job in such a way that as long as it doesn't
have to throw away too many pixels, it will still look good. A cross-
conversion from 1280x720 to 1024x768 isn't bad.

You've spent a lot of time here talking about HD display technology, and
sometime complaining about it, yet you don't have any actual experience
with it.

--
Jeff Rife |
| http://www.nabs.net/Cartoons/ArloNJanis/manure.gif
Anonymous
a b C Monitor
June 16, 2005 10:39:00 PM

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

On Thu, 16 Jun 2005 10:05:46 -0400, Jeff Rife <wevsr@nabs.net> wrote:

>tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
>> I realize there is upconverting and downconverting. I would think that
>> by scaling the picture when it is not necessary, you would naturally
>> incur some distortion which, as I understand it, is not a good thing.
>
>First, for a fixed-pixel display, there is only one resolution where you
>don't have to scale the input signal: the native resolution.
>
>So, a 1280x720 display will scale all other signals to fit. Likewise, a
>1920x1080 display will scale all other signals to fit. There is no way
>around this with a fixed-pixel display.

This is exactly the point, isn't it?
If there was one HDTV standard, fix-pixel displays could be built to
fit at least what regards the number of pixels.

>> I guess you feel adding distortion unnecessarily is OK.
>
>Second, there is no need to introduce "distortion" when scaling.

I don't think the OP means geometric distortion.
Maybe artefacts is a better word, although any deviation from the
original can be called distortion.

>
>A good scaler will do the job in such a way that as long as it doesn't
>have to throw away too many pixels, it will still look good. A cross-
>conversion from 1280x720 to 1024x768 isn't bad.

But you still see the artefacts, or are you saying that you don't?

I have no HDTV-signal yet, but I can see negative effects from the
conversion from 575i to 768p or 720p (really about 550 input lines are
used).
In this case, no information is thrown away but instead the problem is
that information is added when the interpolated pixels are invented.
It is understandable when synthetic menus are displayed because they
are created with the assumption that they are displayed using pixels
exactly as generated. When doing that the Nyquist rule of sampling
does not have to be considered. The sharp edges can not be
interpolated perfectly which results in some slight blurring of
characters in certain spots.

The other type of distortion is when objects move in front of a very
detailed background as when a person moves in front of bushes.

This is partly because the motion prediction introduces artefacts.
I have an LCD TV which also converts frame rate.
I'm not sure to what frequency but my guess is from a field rate of
50Hz to a field rate of either 60 or 75 Hz.
Maybe these effects are smaller on a set without motion prediction but
on the other hand I don't like the "stroboscope" effect that movement
in films create on at least some plasma displays.

/Jan
Anonymous
a b C Monitor
June 16, 2005 10:39:01 PM

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

Jan B (nospam@nospam.se) wrote in alt.tv.tech.hdtv:
> >So, a 1280x720 display will scale all other signals to fit. Likewise, a
> >1920x1080 display will scale all other signals to fit. There is no way
> >around this with a fixed-pixel display.
>
> This is exactly the point, isn't it?
> If there was one HDTV standard, fix-pixel displays could be built to
> fit at least what regards the number of pixels.

You don't have to buy a fixed-pixel display. An advantage to CRTs is
that they kick butt in price/performance.

In addition, if there was only one HDTV resolution, the only one that
would be acceptable in terms of resolution (both pixel and spatial) would
be 1920x1080/60p. Since this can't fit in a 6MHz channel, it's not a
very good choice for a standard.

> >Second, there is no need to introduce "distortion" when scaling.
>
> I don't think the OP means geometric distortion.
> Maybe artefacts is a better word, although any deviation from the
> original can be called distortion.

Find a nice 1280x720 picture. Scale it to 1024x768 using photo editing
software (make sure you turn off any "keep aspect ratio" setting). Then,
scale it back to 1280x720 to simulate the non-square pixels. The only
"artifact" I found was a single pixel move to the right. After adjusting
for that, the images are identical.

> >A good scaler will do the job in such a way that as long as it doesn't
> >have to throw away too many pixels, it will still look good. A cross-
> >conversion from 1280x720 to 1024x768 isn't bad.
>
> But you still see the artefacts, or are you saying that you don't?

Not from HD to HD scaling.

> I have no HDTV-signal yet, but I can see negative effects from the
> conversion from 575i to 768p or 720p (really about 550 input lines are
> used).

When you upscale, you have to "invent" information. There is no way to
do this without introducing something visible. The solution, of course,
would be to make the HD standard the same as the SD standard. Not a good
solution if you like actual HD, though.

--
Jeff Rife | "Wow, I've never seen you this
| bitter...I like it."
|
| -- Richard Karinsky, "Caroline in the City"
Anonymous
a b C Monitor
June 16, 2005 10:39:01 PM

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

On Thu, 16 Jun 2005 18:39:00 GMT, nospam@nospam.se (Jan B) wrote:

>On Thu, 16 Jun 2005 10:05:46 -0400, Jeff Rife <wevsr@nabs.net> wrote:
>
>>tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
>>> I realize there is upconverting and downconverting. I would think that
>>> by scaling the picture when it is not necessary, you would naturally
>>> incur some distortion which, as I understand it, is not a good thing.
>>
>>First, for a fixed-pixel display, there is only one resolution where you
>>don't have to scale the input signal: the native resolution.
>>
>>So, a 1280x720 display will scale all other signals to fit. Likewise, a
>>1920x1080 display will scale all other signals to fit. There is no way
>>around this with a fixed-pixel display.
>
>This is exactly the point, isn't it?
>If there was one HDTV standard, fix-pixel displays could be built to
>fit at least what regards the number of pixels.


Yes that is exactly the point. The current HDTV standard is garbage.

It just takes a lot of research for the non-technical to realize the
emperor has no clothes. I sure don't know what's the excuse for all
the "EXPERTS" here.
Anonymous
a b C Monitor
June 16, 2005 10:39:01 PM

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

On Thu, 16 Jun 2005 18:39:00 +0000, Jan B wrote:


> This is exactly the point, isn't it?
> If there was one HDTV standard, fix-pixel displays could be built to fit
> at least what regards the number of pixels.
>
'One size fits all' formats are what happens when analog guys try to do
digital. Flexibility is a HUGE advantage for going digital, and it would
be very silly to throw it away. A well designed digital system uses
different formats for different program material, using the bits where
they do the most good for that material. Some material deserves higher
spatial resolution, at the expense of temporal resolution. The reverse is
true for other material. Some material doesn't demand much of either, and
the bandwidth saved should be used for other programs.

The audio Compact Disc illustrates the problem. When it was designed,
general purpose digital technology was expensive. The only way to bring
costs down was to pick a single format, implement it all in hardware, and
use economies of scale to make the hardware affordable. It worked, but at
the cost of ALL CDs being 16bit/44.1KHz stereo streams. That's a decent
choice for most music, but a lousy choice for other applications.

Imagine a collection of old radio shows. The programs are in mono, have
limited dynamic range, and narrow bandwidth. But the CD standard limits
such a collection to 72 minutes, because it uses 16 bits, 48KHz, and
stereo when they aren't needed. That's the one and only format supported.
The program only needs something like 12 bits, 20KHz, and mono. With a
flexible, multi-format system, you would be able to fit hours of that
material on a CD. Talking books might need somewhat more resolution, but
not stereo. Reissues of historic mono recordings could use some more, and
so on. At the other extreme, 24 bit, 96KHz, surround sound could be
supported, but with shorter running times.

Digital technology is now dirt cheap, and it costs little to support
flexible systems that use the bandwidth where it's best used. A single
fixed format would be a huge mistake.

Rescaling images to a fixed display resolution can be done quite well, at
low cost. The fact that someone will always find a way to do it poorly
shouldn't be held against the concept of a multi-resolution system. Single
resolution systems can be donw poorly, too.

Broadcasters are picking one single resolution for their networks because
that's easier right now. The equipment will get better, the
one-true-format guys will retire, and eventually stations will switch
resolutions on the fly, using what's best for each program. Sports
*should* be in 720p, movies *should* be in 1080p24, prime-time series
should be in 1080i60, plenty of shows should be 480i/p. The format should
be what's best for the PROGRAM, not what's best for your DISPLAY. Future
displays will have higher resolutions, probably higher than any broadcast
will support. You'll want that for recorded material, and you'll want
that even for broadcasts. It's easy for the recipient to rescale the
program to fit his display, and that's the right thing to do. Fixed
formats are a BAD idea. Imagine if there were only one resolution for
digital still cameras: Yuck!
Anonymous
a b C Monitor
June 17, 2005 6:34:01 AM

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

On Thu, 16 Jun 2005 17:48:07 -0700, "Howard Christeller"
<redacted@noreply.invalid> wrote:

>On Thu, 16 Jun 2005 18:39:00 +0000, Jan B wrote:
>
>
>> This is exactly the point, isn't it?
>> If there was one HDTV standard, fix-pixel displays could be built to fit
>> at least what regards the number of pixels.
>>

>
>Broadcasters are picking one single resolution for their networks because
>that's easier right now. The equipment will get better, the
>one-true-format guys will retire, and eventually stations will switch
>resolutions on the fly, using what's best for each program. Sports
>*should* be in 720p, movies *should* be in 1080p24, prime-time series
>should be in 1080i60, plenty of shows should be 480i/p. The format should
>be what's best for the PROGRAM, not what's best for your DISPLAY. Future
>displays will have higher resolutions, probably higher than any broadcast
>will support. You'll want that for recorded material, and you'll want
>that even for broadcasts. It's easy for the recipient to rescale the
>program to fit his display, and that's the right thing to do. Fixed
>formats are a BAD idea. Imagine if there were only one resolution for
>digital still cameras: Yuck!

Imagine if there were only 480, 720, and 1080 with their variations
all done badly.

Yeah, the little tiles on the space shuttle seemed like a great idea
at the time too.

Wake me when you've got the technology to the point your dreaming of.
June 18, 2005 6:29:53 PM

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

Jeff Rife wrote:
> tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
>
>>I realize there is upconverting and downconverting. I would think that
>>by scaling the picture when it is not necessary, you would naturally
>>incur some distortion which, as I understand it, is not a good thing.
>
>
> First, for a fixed-pixel display, there is only one resolution where you
> don't have to scale the input signal: the native resolution.
>

Of course, but if you pick a native resolution that doesn't match any of
the actual High Def. standards, that's stupid. Then when they make the
pixels rectangular, that's even stupider.
So why wouldn't you at least have one of the High Def. resolutions as
your TV's. I can see having the resolution a bit higher, just leave a
little black at the bottom or on the sides, but not less than that.

> So, a 1280x720 display will scale all other signals to fit.

But a TV with 1024x768 will have to scale all High Def pictures, adding
unnecessary distortion. Then with some TVs having rectangular pixels....
The less upconverting or downconverting you have to do would be the best
solution, regardless of what the salespeople say.

Likewise, a
> 1920x1080 display will scale all other signals to fit. There is no way
> around this with a fixed-pixel display.
>
>
>>I guess you feel adding distortion unnecessarily is OK.
>
>
> Second, there is no need to introduce "distortion" when scaling.
>
> A good scaler will do the job in such a way that as long as it doesn't
> have to throw away too many pixels, it will still look good.

Looking good is fine but looking as exact as possible is better

A cross-
> conversion from 1280x720 to 1024x768 isn't bad.

That's nice but is it as good as 1280x720 on a 1366x768 with a little
black around the edges?

>
> You've spent a lot of time here talking about HD display technology, and
> sometime complaining about it, yet you don't have any actual experience
> with it.
>

No, I am getting up to speed with all of the issues and technologies
before I drop 2-4 grand on a set. By discussing it with you and asking
questions, I will be able to go into a store and understand what is
correct and what is bull-s**t.
Makes sense, doesn't it?
Anonymous
a b C Monitor
June 18, 2005 8:58:14 PM

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

"Jeff Rife" <wevsr@nabs.net> wrote in message
news:MPG.1d1b5146cc98c368989ddd@news.nabs.net...
> tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
>> I realize there is upconverting and downconverting. I would think that
>> by scaling the picture when it is not necessary, you would naturally
>> incur some distortion which, as I understand it, is not a good thing.
>
> First, for a fixed-pixel display, there is only one resolution where you
> don't have to scale the input signal: the native resolution.
>
> So, a 1280x720 display will scale all other signals to fit. Likewise, a
> 1920x1080 display will scale all other signals to fit. There is no way
> around this with a fixed-pixel display.
>
>> I guess you feel adding distortion unnecessarily is OK.
>
> Second, there is no need to introduce "distortion" when scaling.
>
> A good scaler will do the job in such a way that as long as it doesn't
> have to throw away too many pixels, it will still look good. A cross-
> conversion from 1280x720 to 1024x768 isn't bad.
>
> You've spent a lot of time here talking about HD display technology, and
> sometime complaining about it, yet you don't have any actual experience
> with it.
>
> --
> Jeff Rife |
> | http://www.nabs.net/Cartoons/ArloNJanis/manure.gif
>

I'm sure that it depends on the quality of the scaler. For instance, I've
got a 1024x768 Sony XBR plasma set and I really can not tell the difference
between 1080i and 760p for similar program material (comparing two filmed
prime time shows, or live sports events, etc.). I can't speak for other
sets, but mine sure appears to be seamless, at least to my eyes. YMMV

Phil
Anonymous
a b C Monitor
June 18, 2005 8:58:15 PM

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

Phil Ross (paross@pacbell.net) wrote in alt.tv.tech.hdtv:
> I'm sure that it depends on the quality of the scaler.

Today, though, only the really low-ball displays aren't "good enough". At
the medium price range, you can see some variation between manufacturers,
but they generally are all quite good.

And, that was my point. The guy complaining about how horrid it is that a
1024x768 display can be called "HD" just hasn't ever seen one in action.

--
Jeff Rife |
| http://www.nabs.net/Cartoons/Dilbert/Sins.jpg
June 18, 2005 8:58:16 PM

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

Jeff Rife wrote:

> Phil Ross (paross@pacbell.net) wrote in alt.tv.tech.hdtv:
>
>>I'm sure that it depends on the quality of the scaler.
>
>
> Today, though, only the really low-ball displays aren't "good enough". At
> the medium price range, you can see some variation between manufacturers,
> but they generally are all quite good.
>
> And, that was my point. The guy complaining about how horrid it is that a
> 1024x768 display can be called "HD" just hasn't ever seen one in action.
>

Not horrid. Illogical.
Anonymous
a b C Monitor
June 18, 2005 9:09:39 PM

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

"Curmudgeon" <curmudgeon@buzzoff.net> wrote in message
news:7Zrre.119918$J25.25603@bignews6.bellsouth.net...
> Jeff Rife wrote:
>> tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
>>
>>>Why do some TVs and monitors say they are High Def when they don't have
>>>the proper number of vertical lines. For instance, they have a 1024 X 768
>>>display but high def must be at least 1280 x 720, according to the specs.
>>
>>
>> There aren't technically any "rules" for high definition displays, but
>> the members of the Consumer Electronics Association (CEA) agreed that
>> they
>> would advertise displays as follows:
>>
>> For 16x9 displays:
>> - At least 720 progressive scan lines: HD
>> - At least 1080 interlaced scan lines: HD
>>
>> For 4:3 displays
>> - At least 540 progressive scan lines in the 16x9 area and a total of
>> at least 720 progressive scan lines: HD
>> - At least 810 interlaced scan lines in the 16x9 area and a total of
>> at least 1080 interlaced scan lines: HD
>>
>> Notice the lack of any horizontal resolution in these standards? So,
>> a display with a resolution of 1x720 progressive *could* be advertised
>> as HD.
>>
> You're half right.
> In addition to the 720p and 1080i scan line spec, CEA literature and
> advertising directives ALSO provides for the minimum # of pixels to
> qualify as "high definition" : 900,000 to 2.1 million pixels.
> So your assertion that 1x720 could be advertised as HD is dead wrong.
> Check it out at:
> http://www.ce.org/shared_files/resources/DTV_Tip_Sheet....
>

Interesting, but they left a pixel "gap" between EDTV and HDTV. They say
that EDTV provides 300-400,000 pixels and HDTV provides 900,000-2.1 million
pixels. What about those sets that have between 400,001 and 899,999, such as
a 1024x768 display with 786,432 pixels? Super-EDTV, or semi-HDTV? ;-)

Standard Definition TV (SDTV): Basic digital television
transmission that may be displayed with fewer than 480
progressively scanned lines (480p) in 16 x 9 or 4 x 3
format. 480 interlaced (480i) is the quality of today's
analog TV system. SDTV provides 150-300,000 pixels.

Enhanced Definition TV (EDTV): A Better digital
television transmission than SDTV with at least 480p, in
a 16 x 9 or 4 x 3 display and Dolby digital surround
sound. 480p is the quality used by most DVD players.
EDTV provides 300-400,000 pixels.

High-Definition Television (HDTV): The best quality
digital picture, widescreen (16 x 9) display with at least
720 progressively scanned lines (720p) or 1080
interlaced lines (1080i) and Dolby digital surround
sound. HDTV provides 900,000-2.1 million pixels.
Anonymous
a b C Monitor
June 19, 2005 6:13:49 PM

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

Jan B (nospam@nospam.se) wrote in alt.tv.tech.hdtv:
> However, I can clearly see the artefacts created by the conversion
> when (and MPEG reduction as discussed below) for certain image
> content.

Because of the fact that all HD sources are MPEG encoded (at least by
the time it hits the end user), there is no way to know if the artifacts
you are seeing are because of the scaler or because of the MPEG encoding.

A good test would be to use an HTPC and create uncompressed static images
that stress a scaler, then output at various resolutions and let the
display convert.

People have done tests like this at AVS Forum, and universally, the scalers
aren't a problem in any mid-range or higher HDTV display.

> I which there were less MPEG artefacts visible in the SD 575i signal I
> have (via satellite).

Since you aren't dealing with HD, you really don't know that there is a
huge difference in HD as far as MPEG artifacts are concerned. Most SD
transmissions are given less than 3Mbps, while HD gets 16-19Mbps. MPEG
has the odd feature that it does not require linear increases in bit rate
as the number of pixels grow. So, with 4-6 times the number of pixels,
a bitrate of 5-6 times as much results in fewer artifacts.

> That is to say that it is not "good enough" for
> me.

I agree that low bitrate SD is pretty bad. DirecTV (my provider) has
some pretty ugly channels. But, a local broadcaster is sending a single
480i stream using the full 19Mbps allowed by ATSC. That results in a
stunning SD picture.

--
Jeff Rife | "...the flames began at a prophylactic recycling
| plant, near the edge of the forest..."
|
| -- "WarGames"
Anonymous
a b C Monitor
June 19, 2005 6:22:39 PM

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

tim@nocomment.com (tim@nocomment.com) wrote in alt.tv.tech.hdtv:
> My point is, why would a manufacturer
> deliberately introduce these issues when they could just as easily
> create a monitor/TV that did not require all of this software?

Because it isn't possible with a fixed-pixel display. You *have* to choose
a native resolution, and everything else will need to be scaled. If the
scaling is good enough, then it doesn't matter if the native resolution
matches any input resolution.

> At least one format
> should be handled without that though and, for the time being, it seems
> like 1280x720 would be the logical one (although that will be changing
> very soon).

No, 1280x720 is the *worst* one to pick. It requires down-scaling of 1080i
material, which will lose detail. Up-scaling can introduce dither and
thus not lose any resolution (and even make it appear to be better...why
else would an upscaling DVD player be of any value?), so a 1920x1080 native
resolution is the best by far, and is the most logical for today's economy.

The correct logical final fixed-pixel resolution device is 3840x2160, as
that requires the least work in scaling both 720p and 1080i. And, it won't
matter one bit that it doesn't match *any* transmission resolution, as long
as the scaler is halfway decent. The same applies for *every* choice of
resolution on a fixed-pixel display.

--
Jeff Rife |
| http://www.nabs.net/Cartoons/OverTheHedge/Olympics.gif
Anonymous
a b C Monitor
June 19, 2005 7:13:24 PM

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

"Jeff Rife" <wevsr@nabs.net> wrote in message
news:MPG.1d1e4133ac55636f989ddf@news.nabs.net...
> Phil Ross (paross@pacbell.net) wrote in alt.tv.tech.hdtv:
>> I'm sure that it depends on the quality of the scaler.
>
> Today, though, only the really low-ball displays aren't "good enough". At
> the medium price range, you can see some variation between manufacturers,
> but they generally are all quite good.
>
> And, that was my point. The guy complaining about how horrid it is that a
> 1024x768 display can be called "HD" just hasn't ever seen one in action.
>
> --
> Jeff Rife |
> | http://www.nabs.net/Cartoons/Dilbert/Sins.jpg

By the way, I was agreeing with you. Also, because of the many different
standards for DTV and HD, all fixed pixel display types will require scaling
for any format other than what is native to the display. This guy doesn't
seem to get that this really works just fine. Oh well.
Anonymous
a b C Monitor
June 22, 2005 5:09:02 PM

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

dOinK (tvanvik@on-delete-this-line.no) wrote in alt.tv.tech.hdtv:
> I dont't think arguing that everything looks good from a distance makes much
> sense. The required size of the screen depends on the viewing distance. For
> optimal viewing, the distance should be such that you can see all the
> details, i.e. practically every single pixel.

For a TV, that's wrong. Even on a computer monitor, you can't see every
pixel until you press your nose up against the screen. You can see the
*effect* of single pixels quite often (like the font I am using right now
has lines that are one pixel thick), but you can't make out the individual
pixels (I can't count how many pixels high the capital letters are, because
a line of pixels blends together).

To be able to really see every pixel, the seating distance for a 72"
1920x1080 display would be 9 feet for sharp-eyed people (based on the
fact that humans can discern objects that occupy about 1 minute of arc).

For a 42" 1920x1080 display, the "see every pixel" seating distance would
be 5-1/4 feet. Do you know anybody who has a couch that close to their
TV?

--
Jeff Rife |
| http://www.nabs.net/Cartoons/RhymesWithOrange/Obedience...
Anonymous
a b C Monitor
June 22, 2005 6:05:07 PM

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

I appreciate your questions, Tim, and agree with your ideas. I'd like a
screen that is able to show all pixels without conversion! I've owned a
1080i CRT TV, and there is a noticeable decrease in quality and detail when
downsampling (e.g. throug the cable box or the TV), unless you sit FAR away
(or have bad sight). Also, it is quite easy to see the quality reduction
when resampling (down) images on a LCD monitor, for people who look for
details. Keep up the good attitude!

dOinK
Anonymous
a b C Monitor
June 22, 2005 6:05:08 PM

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

dOinK (tvanvik@on-delete-this-line.no) wrote in alt.tv.tech.hdtv:
> I'd like a
> screen that is able to show all pixels without conversion! I've owned a
> 1080i CRT TV, and there is a noticeable decrease in quality and detail when
> downsampling (e.g. throug the cable box or the TV), unless you sit FAR away
> (or have bad sight).

Then, you had a fairly poor TV, since a display that handles 1080i doesn't
ever "downsample" on any video mode. 720p -> 1080i increases the number
of pixels, and of course every SD to HD mode does likewise.

The actual measured resolution on my direct-view CRT set is between 1200
and 1500 pixels in each horizontal line, and a full 1080 lines. Even so,
a 1366x853 plasma has almost as good a display as far as resolution is
concerned, even on 1080i source material.

When you get out there and look at quality displays, you'll see that there
isn't really an issue.

--
Jeff Rife | Coach: Yeah, Norm, how come you and Vera never
| had any kids?
| Norm: I can't, Coach.
| Coach: Gee, I'm sorry, Norm.
| Norm: I look at Vera...and I just can't.
Anonymous
a b C Monitor
June 23, 2005 3:03:52 AM

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

On Wed, 22 Jun 2005 13:09:02 -0400, Jeff Rife <wevsr@nabs.net> wrote:

>dOinK (tvanvik@on-delete-this-line.no) wrote in alt.tv.tech.hdtv:
>> I dont't think arguing that everything looks good from a distance makes much
>> sense. The required size of the screen depends on the viewing distance. For
>> optimal viewing, the distance should be such that you can see all the
>> details, i.e. practically every single pixel.
>
>For a TV, that's wrong. Even on a computer monitor, you can't see every
>pixel until you press your nose up against the screen.

Well, on the laptop I have a pixel pitch of 0.24mm. At a distance of
0.6m that is 1.3 arc minutes. I just did a test. I can clearly see the
difference of 2 adjecent white pixels on a dark backround compared to
only one white pixel. But maybe that is what you mean, I can't see if
the pixels are squared or round.

> You can see the
>*effect* of single pixels quite often (like the font I am using right now
>has lines that are one pixel thick), but you can't make out the individual
>pixels (I can't count how many pixels high the capital letters are, because
>a line of pixels blends together).

Pixels don't blend that good on the mentioned laptop panel (768 lines
12"). It gives a little screendoor effect (but it works OK for text).
I did not expect this display to be good for pictures so I mention it
only for comparison since you brought it up.

>To be able to really see every pixel, the seating distance for a 72"
>1920x1080 display would be 9 feet for sharp-eyed people (based on the
>fact that humans can discern objects that occupy about 1 minute of arc).


I use that value as a guidline but the other way around. I don't want
to be able to resolve the pixels so I sit furter away. I want a smooth
picture and the jagged lines should not be visible. 0.5mm pixel pitch
at about 2.5m distance works OK for me. That is about 0.7 arc minutes.
Still pictures (photos) via the VGA input look good even though they
are downsampled from 1280x960 to 1024x768 . I believe that the
artefacts I see on the TV signal is because of the resampling in
combination with the needed conversion from interlaced and conversion
from one frame rate to another. With the SD signal of 720x576i an
upsampling is needed which I think is likely to be more problematic.

>For a 42" 1920x1080 display, the "see every pixel" seating distance would
>be 5-1/4 feet. Do you know anybody who has a couch that close to their
>TV?

Calculated from 0.7 arc minutes on my 30" panel I could go to 42" at
the same distance with 1080 lines instead of 720. But i would like
less artefacts. I don't believe these artefacts, which now and then
surround a moving object in front of an irregular backround, could
excist if the display would map the pixels 1:1 and update exactly with
the signal frame rate.
( I'm not talking about the usual MPEG artefacts where square areas
gets a little too low colour resolution to stay within the given bit
rate, although these blocks might very well cause problems for the
resampling.)
/Jan
Anonymous
a b C Monitor
June 23, 2005 3:05:37 AM

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

Jan B (nospam@nospam.se) wrote in alt.tv.tech.hdtv:
> Well, on the laptop I have a pixel pitch of 0.24mm. At a distance of
> 0.6m that is 1.3 arc minutes. I just did a test. I can clearly see the
> difference of 2 adjecent white pixels on a dark backround compared to
> only one white pixel.

Now, draw a line of a random number of pixels between 10 and 20. Count
them without straining. If you can, then you can distinguish individual
pixels.

> Pixels don't blend that good on the mentioned laptop panel (768 lines
> 12"). It gives a little screendoor effect (but it works OK for text).

Yeah, that's one thing that start to show up if you are too close to a
fixed pixel display.

I'm about 24" from my 1600x1200 20" monitor, but don't see a screen door
effect, even though it's about the same pixel size (1.4' of arc).

--
Jeff Rife |
| http://www.nabs.net/Cartoons/Dilbert/Win95CatOnMonitor....
!