1080p vs 1080i
 

Is it correct to say that both have the same spatial resolutions, but
each pixel in the picture is refreshed at a different rate b/w the two
formats?

In theory, the higher the update rate the better (this is not hard to
understand). But there has to be a threshold, due to physiology of
human vision, beyond which point it doesn't matter anymore.

Is 30Hz not enough to "fool" human eyes?

1080p vs 1080i
 

wrote in message
oups.com...
Is it correct to say that both have the same spatial resolutions, but
each pixel in the picture is refreshed at a different rate b/w the two
formats?

In theory, the higher the update rate the better (this is not hard to
understand). But there has to be a threshold, due to physiology of
human vision, beyond which point it doesn't matter anymore.

Is 30Hz not enough to "fool" human eyes?



watch a video game running at 30fps and then one running at 60fps.
if you cant tell the difference....



--
Gareth.

That fly... is your magic wand.
http://www.last.fm/user/dsbmusic/

1080p vs 1080i
 

1080p vs 1080i
 

Film is not shown in theatres at 48 fps, it is 24 fps divided by 4.
The "intermittent/Geneva" movement and shutter work in the following way:

1. the rotary shutter is closed and the next frame of the film is pulled
down in 1/96th of a second.

2. The shutter opens and shows the still image for 1/96th of a second.

3. The shutter closes for 1/96th of a second.

4. The shutter opens again for 1/96th of a second.

shutter time open = 1/48th of a second
shutter time closed = 1/48th of a second

Our brains interpret the still images into a "moving " image.

If you had unequal shutter openings and closings you would get a headache..

Sam Soltan,
member IATSE Local 306 NYC Motion Picture Machine Operators,
past member SMPTE.
currently Industrial Technology Teacher
"Alan F" wrote in message
news:[email protected]
wrote:
Is it correct to say that both have the same spatial resolutions, but
each pixel in the picture is refreshed at a different rate b/w the two
formats?

In theory, the higher the update rate the better (this is not hard to
understand). But there has to be a threshold, due to physiology of
human vision, beyond which point it doesn't matter anymore.

Is 30Hz not enough to "fool" human eyes?

Using the common nomenclature, 1080i is at 60 Hz. It is simply 1/2 of
the scan lines updated 60 times a second in an alternating pattern.
1080/60i is NOT, repeat, NOT the same as 1080/30p. You may understand
this or not, but way too many people don't.

Most scripted TV shows are shot on film or HD video cameras designed
to emulate film at 24 fps. If the video is sent correctly and the TV
de-interleaves it correctly, 1080/60i can be de-interleaved to 24p.
There is no real advantage to 1080/60p for 24 fps signal sources.

Film is shot at 24 frames per second, but shown in movie theaters at
48 fps because a 30 Hz rate does show flicker. This is why way back in
the dawn of TV, 60 Hz (NTSC) and 50 Hz (PAL in Europe and elsewhere)
were chosen as the basic refresh rates.

This gets technical and long winded in a hurry. Find some websites or
read a book or two on video processing for details. Maybe a real TV or
video engineer will be willing to reply.

Alan F

1080p vs 1080i
 

1080p vs 1080i
 

On Oct 5, 3:23 pm, wrote:
Is it correct to say that both have the same spatial resolutions, but
each pixel in the picture is refreshed at a different rate b/w the two
formats?

In theory, the higher the update rate the better (this is not hard to
understand). But there has to be a threshold, due to physiology of
human vision, beyond which point it doesn't matter anymore.

Is 30Hz not enough to "fool" human eyes?

I want to go to a store and have them set up 2 of the same tv's and
have one signal at 1080p and another at 1080i so I can see the
difference. Is Comcast transmitting in 1080p? The store would have
to have a 1080p signal, though...

Are the HD dvd's 1080i or 1080p?

Thanks!

Eddie G

1080p vs 1080i
 

On Fri, 5 Oct 2007 17:06:24 -0400 Sam Soltan samsoltan_48323atyahoodotcom wrote:

| Film is not shown in theatres at 48 fps, it is 24 fps divided by 4.
| The "intermittent/Geneva" movement and shutter work in the following way:
|
| 1. the rotary shutter is closed and the next frame of the film is pulled
| down in 1/96th of a second.
|
| 2. The shutter opens and shows the still image for 1/96th of a second.
|
| 3. The shutter closes for 1/96th of a second.
|
| 4. The shutter opens again for 1/96th of a second.
|
| shutter time open = 1/48th of a second
| shutter time closed = 1/48th of a second
|
| Our brains interpret the still images into a "moving " image.
|
| If you had unequal shutter openings and closings you would get a headache..

That _is_ 48 fps. It's not 48 different film frames; it's just 48 projection
frames. The shutter opens 48 times a second with nice even spacing.

Now if you increased the rate to 60 fps, with 1/120th second timings
as given above, with half the frames shown 2 times and half shown 3
times, you'd have the judder effect as seen on TV.

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / |
|------------------------------------/-------------------------------------|

1080p vs 1080i
 

On Fri, 05 Oct 2007 21:07:03 GMT Usenet Reader wrote:
| wrote:
| Is it correct to say that both have the same spatial resolutions, but
| each pixel in the picture is refreshed at a different rate b/w the two
| formats?
|
| In theory, the higher the update rate the better (this is not hard to
| understand). But there has to be a threshold, due to physiology of
| human vision, beyond which point it doesn't matter anymore.
|
| Is 30Hz not enough to "fool" human eyes?
|
| It may not be as obvious at that. The mechanics of interlacing does
| introduce some artifacts that wouldn't be there otherwise - particularly
| with motion. Just as when you take a picture with a high resolution
| digital camera - of something that has fine vertical or horizontal lines
| in it, maybe not even detectable in analog (film) - you get a dizzying
| (moir?) effect - particularly with video. Interlacing has a similar
| effect, and when you capture an interlaced broadcast to digital video,
| you absolutely have to de-interlace the stream or the playback will look
| much worse than the original.

That's why we should get rid of interlacing as soon as we can.

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / |
|------------------------------------/-------------------------------------|

1080p vs 1080i
 

Eddie G wrote:
On Oct 5, 3:23 pm, wrote:
Is it correct to say that both have the same spatial resolutions, but
each pixel in the picture is refreshed at a different rate b/w the two
formats?

In theory, the higher the update rate the better (this is not hard to
understand). But there has to be a threshold, due to physiology of
human vision, beyond which point it doesn't matter anymore.

Is 30Hz not enough to "fool" human eyes?

I want to go to a store and have them set up 2 of the same tv's and
have one signal at 1080p and another at 1080i so I can see the
difference. Is Comcast transmitting in 1080p? The store would have
to have a 1080p signal, though...

Are the HD dvd's 1080i or 1080p?

Thanks!

Eddie G

No one broadcasts at 1080/60p or even at 1080/24p (which is one of the
18 ATSC standard formats). The only common source for that is going to
be a computer generated video or 1080/60p video which is high end
equipment at this point.

The issue is the source. Is it film shot at 24 fps or video cameras at
50i (Europe) or 60i? Comparing 1080p versus 1080i is not a simple thing
to do.

The movies on HD-DVDs which were shot on film are stored at 24p.
Sources from video cameras might be different - 50i, 60i, 30p, whatever.
The earlier HD-DVD players could only output up to 1080/60i, the most
recent generation nows provides for a 1080/24p output. Not sure if they
support 1080/60p yet, but then most TVs up to this year didn't either.

Because almost flat panel and RP TV based on LCD, DLP, SXRD/D-ILA/LCOS
TVs are inherently progressive displays, the stores and TV manufacturers
push 1080p as if it were the greatest thing since sliced bread. The fact
that most HD channels are 1080i just confuses people.

Alan F

1080p vs 1080i
 

"Alan F" wrote in message
news:[email protected]
Eddie G wrote:
On Oct 5, 3:23 pm, wrote:
Is it correct to say that both have the same spatial resolutions, but
each pixel in the picture is refreshed at a different rate b/w the two
formats?

In theory, the higher the update rate the better (this is not hard to
understand). But there has to be a threshold, due to physiology of
human vision, beyond which point it doesn't matter anymore.

Is 30Hz not enough to "fool" human eyes?

I want to go to a store and have them set up 2 of the same tv's and
have one signal at 1080p and another at 1080i so I can see the
difference. Is Comcast transmitting in 1080p? The store would have
to have a 1080p signal, though...

Are the HD dvd's 1080i or 1080p?

Thanks!

Eddie G

No one broadcasts at 1080/60p or even at 1080/24p (which is one of the
18 ATSC standard formats). The only common source for that is going to
be a computer generated video or 1080/60p video which is high end
equipment at this point.

The issue is the source. Is it film shot at 24 fps or video cameras at
50i (Europe) or 60i? Comparing 1080p versus 1080i is not a simple thing
to do.

The movies on HD-DVDs which were shot on film are stored at 24p.
Sources from video cameras might be different - 50i, 60i, 30p, whatever.
The earlier HD-DVD players could only output up to 1080/60i, the most
recent generation nows provides for a 1080/24p output. Not sure if they
support 1080/60p yet, but then most TVs up to this year didn't either.

Because almost flat panel and RP TV based on LCD, DLP, SXRD/D-ILA/LCOS
TVs are inherently progressive displays, the stores and TV manufacturers
push 1080p as if it were the greatest thing since sliced bread. The fact
that most HD channels are 1080i just confuses people.

This is what I thought after my post. So there is no reason to buy a 1080p
TV or worry about a home theater receiver that has 1080i vs 1080p for it's
HDMI interface? Will there be a reason for 1080p in the near future, or
should I get a 1080i set and not worry about it?

Eddie