How close to the screen...
 

....would you need to sit to observe the difference between 1080 and
720 on SD and HD? At 10 feet would there be a noticeable difference
with a 42 inch screen?
--
rbel

How close to the screen...
 

rbel wrote:

...would you need to sit to observe the difference between 1080 and
720 on SD and HD? At 10 feet would there be a noticeable difference
with a 42 inch screen?

A serious answer to this is that it all depends on your eyesight. You
can work it out for yourself: most "authorities" agree that the eye can
resolve down to about a minute of arc, so if you work out the physical
size of a pixel at those resolutions on your 42" screen, then use a bit
of trigonometry to work out whether either (or both) subtends more than
a minute of arc. If the answer is yes, then you will be able to see
the difference.

I wasn't being flippant with the glasses comment. I followed the above
procedure to work out the biggest TV screen I could get away with for
my viewing distance, but then found in practice that I could only
resolve the pixels if I made my eyesight perfect by wearing my glasses.
Without glasses my distance vision is still damn good, but I couldn't
make out the pixels.

--
SteveT

How close to the screen...
 

On Sat, 29 Jun 2013 13:11:54 -0500, "Steve Thackery"
wrote:

rbel wrote:

...would you need to sit to observe the difference between 1080 and
720 on SD and HD? At 10 feet would there be a noticeable difference
with a 42 inch screen?

A serious answer to this is that it all depends on your eyesight. You
can work it out for yourself: most "authorities" agree that the eye can
resolve down to about a minute of arc, so if you work out the physical
size of a pixel at those resolutions on your 42" screen, then use a bit
of trigonometry to work out whether either (or both) subtends more than
a minute of arc. If the answer is yes, then you will be able to see
the difference.

I wasn't being flippant with the glasses comment. I followed the above
procedure to work out the biggest TV screen I could get away with for
my viewing distance, but then found in practice that I could only
resolve the pixels if I made my eyesight perfect by wearing my glasses.
Without glasses my distance vision is still damn good, but I couldn't
make out the pixels.

Many thanks for the response. I appreciate that it does depend on
just how good eyesight is, but to simplify matters I was working under
the assumption that the viewer's eyesight would be corrected if
necessary to the viewing distance.
--
rbel

How close to the screen...
 

I'm hoping someone else will check my calculations for me, but here is
what I've found. On a 42" 16:9 screen viewed at 10ft:

At 1080 pixels, each pixels subtends 0m 58s of arc

At 720 pixels, each pixel subtends 1m 27s of arc

In other words, with perfect eyesight you will (in theory) be able to
discern the individual pixels when set to SD, but not when set to HD.

In simple terms, your eye can resolve more detail than the SD picture
can show, whereas the HD picture will be just beyond the limit of what
your eye can resolve.

Therefore yes; with perfect eyesight, you probably will see a
difference between SD and HD.

Here is why I don't think the above means much. Many SD broadcasts
(such as BBC East Midlands, where I live) seem to use crummy old
cameras and/or other equipment, such that the pictures seem far worse
than just 720 pixels worth of pixellation. They even have odd ringing
artifacts and general fuzziness. On the other hand, most HD broadcasts
(at least on the BBC) seem to use much better kit, and usually they
make every pixel pay its way and look great.

Incidentally, due to the compressed nature of our I think you'll find
the compression artefacts more intrusive than the limitations of the
resolution. Once again, I don't recall noticing any compression
artifacts on the BBC HD channels, but on some of the less popular
commercial channels it can be terrible.

--
SteveT

How close to the screen...
 

In article ,
Steve Thackery wrote:

I'm hoping someone else will check my calculations for me, but here is
what I've found. On a 42" 16:9 screen viewed at 10ft:

At 1080 pixels, each pixels subtends 0m 58s of arc

At 720 pixels, each pixel subtends 1m 27s of arc

In other words, with perfect eyesight you will (in theory) be able to
discern the individual pixels when set to SD, but not when set to HD.

In simple terms, your eye can resolve more detail than the SD picture
can show, whereas the HD picture will be just beyond the limit of what
your eye can resolve.

Therefore yes; with perfect eyesight, you probably will see a
difference between SD and HD.

Here is why I don't think the above means much. Many SD broadcasts
(such as BBC East Midlands, where I live) seem to use crummy old
cameras and/or other equipment, such that the pictures seem far worse
than just 720 pixels worth of pixellation. They even have odd ringing
artifacts and general fuzziness. On the other hand, most HD broadcasts
(at least on the BBC) seem to use much better kit, and usually they
make every pixel pay its way and look great.

Incidentally, due to the compressed nature of our I think you'll find
the compression artefacts more intrusive than the limitations of the
resolution. Once again, I don't recall noticing any compression
artifacts on the BBC HD channels, but on some of the less popular
commercial channels it can be terrible.

In our case we have a 32" Panasonic with a 10' viewing distance. The
difference between SD & HD on the same programme is very noticeable. No
theory, just an observed fact.

--
From KT24

Using a RISC OS computer running v5.18

How close to the screen...
 

On Sat, 29 Jun 2013 20:07:49 +0100, charles
wrote:

In article ,
Steve Thackery wrote:

I'm hoping someone else will check my calculations for me, but here is
what I've found. On a 42" 16:9 screen viewed at 10ft:

At 1080 pixels, each pixels subtends 0m 58s of arc

At 720 pixels, each pixel subtends 1m 27s of arc

In other words, with perfect eyesight you will (in theory) be able to
discern the individual pixels when set to SD, but not when set to HD.

In simple terms, your eye can resolve more detail than the SD picture
can show, whereas the HD picture will be just beyond the limit of what
your eye can resolve.

Therefore yes; with perfect eyesight, you probably will see a
difference between SD and HD.

Here is why I don't think the above means much. Many SD broadcasts
(such as BBC East Midlands, where I live) seem to use crummy old
cameras and/or other equipment, such that the pictures seem far worse
than just 720 pixels worth of pixellation. They even have odd ringing
artifacts and general fuzziness. On the other hand, most HD broadcasts
(at least on the BBC) seem to use much better kit, and usually they
make every pixel pay its way and look great.

Incidentally, due to the compressed nature of our I think you'll find
the compression artefacts more intrusive than the limitations of the
resolution. Once again, I don't recall noticing any compression
artifacts on the BBC HD channels, but on some of the less popular
commercial channels it can be terrible.

In our case we have a 32" Panasonic with a 10' viewing distance. The
difference between SD & HD on the same programme is very noticeable. No
theory, just an observed fact.

Steve and Charles, thanks for commenting on the discernable difference
between SD and HD and the impact of other factors. How about the
difference between a 720p set and a 1080p set when applied to either
HD or SD?
--
rbel

How close to the screen...
 

rbel wrote:

On Sat, 29 Jun 2013 20:07:49 +0100, charles
wrote:

In article ,
Steve Thackery wrote:

I'm hoping someone else will check my calculations for me, but
here is what I've found. On a 42" 16:9 screen viewed at 10ft:

At 1080 pixels, each pixels subtends 0m 58s of arc

At 720 pixels, each pixel subtends 1m 27s of arc

In other words, with perfect eyesight you will (in theory) be able
to discern the individual pixels when set to SD, but not when set
to HD.

In simple terms, your eye can resolve more detail than the SD
picture can show, whereas the HD picture will be just beyond the
limit of what your eye can resolve.

Therefore yes; with perfect eyesight, you probably will see a
difference between SD and HD.

Here is why I don't think the above means much. Many SD broadcasts
(such as BBC East Midlands, where I live) seem to use crummy old
cameras and/or other equipment, such that the pictures seem far
worse than just 720 pixels worth of pixellation. They even have
odd ringing artifacts and general fuzziness. On the other hand,
most HD broadcasts (at least on the BBC) seem to use much better
kit, and usually they make every pixel pay its way and look great.

Incidentally, due to the compressed nature of our I think you'll
find the compression artefacts more intrusive than the limitations
of the resolution. Once again, I don't recall noticing any
compression artifacts on the BBC HD channels, but on some of the
less popular commercial channels it can be terrible.

In our case we have a 32" Panasonic with a 10' viewing distance.
The difference between SD & HD on the same programme is very
noticeable. No theory, just an observed fact.

Steve and Charles, thanks for commenting on the discernable difference
between SD and HD and the impact of other factors. How about the
difference between a 720p set and a 1080p set when applied to either
HD or SD?

I don't have any experience, as I've always had 1920 * 1080 sets since
I went digital. Obviously a 1080 set must scale 720 pictures up, and
vice versa. I don't think scaling does much "damage" to the picture,
although we've got some broadcast experts amongst us who will be able
to tell us more.

For what it's worth, I would never buy any TV these days unless it:

1/ Has a 1920 * 1080 screen and 'Full HD' on a sticker

2/ Has a Freeview HD sticker on it, too

That way you've got a full HD screen and a full HD Freeview tuner.

If you're anything like me, you'll try to watch HD whenever you can,
because it looks so much better than SD. I promise you won't regret it.

--
SteveT

How close to the screen...
 

In article ,
charles wrote:
In our case we have a 32" Panasonic with a 10' viewing distance. The
difference between SD & HD on the same programme is very noticeable. No
theory, just an observed fact.

But the screen resolution may not be responsible. Compressed
broadcast video does not by any means give you the quality that
your screen is capable of. I suspect that if DVB-2 at the bit
rate used for Freeview HD was applied to a 625-line broadcast,
the quality would be very impressive!

-- Richard

How close to the screen...
 

rbel wrote in message ...
...would you need to sit to observe the difference between 1080 and
720 on SD and HD? At 10 feet would there be a noticeable difference
with a 42 inch screen?
--
rbel

It will depend on eyesight, but assuming you have good vision or the right
glasses then you will be able to see a difference between 720 and 1080 at 3m
(or equivalent distance for a smaller / larger screen). I can certainly
easily tell the difference between full HD and SD at 3.5m on a 42" and the
former is much better.

OTOH at 7 to 8m I can't tell the difference between SD (576) and 1080 on a
42" screen (and I have negative acuity).

How close to the screen...
 

In article ,
Richard Tobin wrote:
In article ,
charles wrote:
In our case we have a 32" Panasonic with a 10' viewing distance. The
difference between SD & HD on the same programme is very noticeable. No
theory, just an observed fact.

But the screen resolution may not be responsible. Compressed
broadcast video does not by any means give you the quality that
your screen is capable of. I suspect that if DVB-2 at the bit
rate used for Freeview HD was applied to a 625-line broadcast,
the quality would be very impressive!


I didn't mention screen resolution, I simply said that HD gives a better
picture at 10ft.

--
From KT24

Using a RISC OS computer running v5.18