How discernable is 1080p over 1080i ?

[JimPullan]

There are a multitude of 1080i HDTV's having been sold and now the introduction of the 1080p displays. With the advent of the 1080p capable Blu-Ray players, can the average consumer actually see a difference between a 1080p movie over the exact 1080i movie ? Will a 1080p experience be any more thrilling than the 1080i experience ?

Jim

[Deciazulado]

depends on several factors, Jim,

A: An image optimized (or video filtered) for interlaced display has a resolution equivalency or sharpness that can be down to approx. 70% (some call it the Kell factor) of a progressive image in a worst case scenario. (In other words, "It's all in the mastering!")

B: Your 1080i input display or player could either deinterlace correctly (weave) or "incorrectly" (bob) a progressive (film) image, and of course all 1080p displays and/or 1080p output players have to deinterlace interlaced (shot on HDTV video) images by some method, ranging from optimally (motion pixel adaptive, etc, etc), to the more common bob, that again, at worst, would give you 70% of the sharpness. (In other words, "It's all in the deinterlacing!")

Remember this reduction to 70% of 1080p can happen if the transfer is "suboptimal" and you have a 1080p player -> 1080p display; or if the transfer is "perfect" and at some point between the 1080 player and 1080 display there's a worst (bob) deinterlace occurring.*

So depending on those two factors, a 1080i vs 1080p path can vary from the 1080i being equivalent to about 768p, to looking equal to 1080p

(If you wanna play the laws of averages between the extremes of those two possibilities occurring :-P, that comes out to be about 900p, which in comparison to 1080p is: about the same difference between a 16:9 coded widescreen movie DVD and a 4:3 coded widescreen movie DVD).

Then:

C: Seating distance also affects perceived quality:

The eye finds an about 2000p image to be excellent at 0.8x screen width viewing distance from a 16:9 screen.

At 1x screen width sitting distance 1600p
At 1.25x screen width sitting distance 1250p
At 1.6x screen width sitting distance 1000p
At 2x screen width sitting distance 800p
At 2.5x screen width sitting distance 640p
At 3.2x screen width sitting distance 500p
At 4x screen width sitting distance 400p

(In other words, "It's all in how close you sit to the screen!")


D: You may also tolerate a less than excellent image (well, we accept average 35mm theatrical projection which is miles away from perfectly focused 70mm, etc ) For example, tho a 2000p image watched 9 feet from a 16:9 wide 12 feet diagonal screen will look outstanding, that doesn't mean a 1000p image will look bad, it'll look great still. (In other words, "It's all in what you think is good enough!")

E: A judiciously adjusted sharpness control with proper contrast and black level can do wonders to a slightly fuzzy image :-P (In other words nothing beats a correctly calibrated home theater!)

F: So in answer to your question: In some cases it might be more thrilling, (but if you have 1080i now don't worry about it and start enjoying your 6x times better than interlaced NTSC DVD video

G: I can't wait for Blu-ray





*(With both the transfer and the deinterlacing being bad occurring at the SAME time we would still end up with the same potential 70% of max, since what is happening on both process is just putting the same cap on the vertical resolution) (Well, one would hope!)

[JimPullan]

Thanks so much for the detailed explanation. It was certainly more than what I expected. You sure did your homework on this. Again, thanks!

Jim

[vick vega]

yeah, no doubt that was the easiest to understand explanation of 1080i vs. 1080p

[Cysquatch]

i just bought a 1080i 50" plasma and was wondering the exact same thing. Thanks so much for the explanation. 1080p would be awesome but I couldn't pass up the price of the plasma.

[PurpleAardvark]

Good exp. Just saw the price tag on that new 1080p 65" plasma $10,000. Since we are all such loyal BD fans here I know NYG is going to buy one for each of us at Christmas. 2 for me seeing how I don't get the free panny. Here is the link:

http://www.crutchfield.com/S-rV5QSx7...0&I=13365PX600

[Zvi]

Originally Posted by Deciazulado

C: Seating distance also affects perceived quality:

The eye finds an about 2000p image to be excellent at 0.8x screen width viewing distance from a 16:9 screen.

Deci, can you clarify a little bit more on that? 0.8x? So, for m 61" Sammy I should be sitting less than 5 ft from it? I thought optimal distance was 8-9 ft for that screen with 1080p.

[Deciazulado]

Originally Posted by Deciazulado

C: Seating distance also affects perceived quality:

The eye finds an about 2000p image to be excellent at 0.8x screen width viewing distance from a 16:9 screen.

Originally Posted by Zvi

Deci, can you clarify a little bit more on that? 0.8x? So, for m 61" Sammy I should be sitting less than 5 ft from it? I thought optimal distance was 8-9 ft for that screen with 1080p.

mmm. I measure in PH (picture heights, because movies are projected at constant height and is the width that changes). THX TAP recommends 1.42 PH for the closest viewing distance (not to be confused with the bad front row seats where you damage your neck looking up!), while the minimum size you should be watching a film (the last row on a theater, the worst seat) should be at 3.61 PH. (See top left image of page 25 of this PDF document for a 450 square feet (approx. 14' x 33') 35mm state-of-the-art THX film dubbing stage)

For a 16:9 wide screen (1.78 wide), 1.42PH is 0.8 screen widths.

At that distance the eye could distinguish about 4000 pixels from top to bottom (4000p) under some circumstances, but those details would be at the very threshold of vision and probably not be seen more than half of the time.

With details twice as thick (only 2000 pixels, or "2000p"), that would be the practical limit with an image virtually indistinguishable from the 4000p one. (I'd say 4000p would look 5% better at that viewing distance, but for that improvement you'd need 400% the bandwidth or data!)


So again, in practical terms at approx. 1.5 PH (0.8 screen width for a 16:9 display) the eye finds an about 2000p image to be excellent.

With 1000p at that distance the image would be very good.

2000p would be equivalent to 70mm while 1000p would be the equivalent of 35mm


61" 16:9 Sammy screen is 30" x 53". Sitting at 9 feet (108") the numbers would be (assuming no overscan):

1.37 movies at 3.6PH (or 2.6 screen widths)
1.78 HDTV at 3.6PH (or 2 screen widths)
1.85 movies at 3.7PH (or 2 screen widths)
2.39 movies at 4.8PH (or 2 screen widths)

As you can see those viewing distances are like watching a film in the last row of a theater. That would make 35mm film (or 1000p) look as sharp as 70mm film, but of course then the field of view is 4 times as small as the one you get by sitting in the middle or the front on the theater, where you experience the unique telepresence that only Cinema with its 35mm (and 70mm) film could give until now.





If I sit on the last row of a theater, I feel like I'm watching through a small window, called TV. Or DVD.





61" 16:9 Sammy screen is 30" x 53". Sitting at 5 feet (60") the numbers would be:

1.37 movies at 2PH (or 1.45 screen widths)
1.78 HDTV at 2PH (or 1.13 screen widths)
1.85 movies at 2.1PH (or 1.13 screen widths)
2.39 movies at 2.7PH (or 1.13 screen widths)


(Remember that all movies screen image heights should be the same, but since the display is only 1.78 wide, wider films than that get shrunk)

[Zvi]

Thanks Deci. That's some complicated calcs right there, but quite interesting

[i want HD movies]

The other thing to consider is that most 1080i tv's are actually 1300 x 720. for the non technically oriented simply 720p is all 720 lines, whereas 1080i is only 540 at any given time meaning all 720p sets are technically 1080i also.

on a set that is 1920 x 1080, there will be little discernability between 1080i and 1080p since the tv, assuming it does a decent job, will simply be deinterlacing the full resolution. Very few sets ever fit this category though as most tv's which do 1920 x 1080 are already 'p' capable. The only exception that I can readiy think of is the first Sharp 45" LCD we carried that ony did 1080i.

[Typhon]

so what ur saying is that its 1920x540?..LMAO !! ok

[i want HD movies]

yes in sorts. interlaced means that only half of the total lines are processed at a time.

You can notice the jumpiness in fast moving objects. For instance if you watch Discovery HD and things move faster than in a slow pan shot, 1080i reveals its movement issues to those with keen eyes. This is why Fox chose 720p, it concentrates on sporting events more than nature pan shots.

as it was said earlier in the thread:
"a 1080i vs 1080p path can vary from the 1080i being equivalent to about 768p, to looking equal to 1080p"

how bout some from cnet:
"1080i - 1080 interlaced; one of two formats designated as high-definition television in the ATSC DTV standard, with 1,080 vertical pixels by 1,920 horizontal pixels. The i stands for interlaced, as opposed to progressive scanning, used in the second HDTV standard, 720p. Contrary to myth, 1080i is not superior to 720p; 1080i has more scanning lines but also suffers the disadvantages of interlaced scanning."

no? how bout wikipedia then:
"Some people prefer to use the line number of fields, which is half that of frames, in their nomenclature and thus call this mode 540i"

Again the difference is minimal but noticable (to some) between 1080i and 1080P. My point is that the TV may be 1920 x 1080, or 1366 x 768. That is the biggest difference. Nearly twice the pixels in a 1080p set.

[Blumovie]

The question is in the title!

Thanks,

[Longshot]

Originally Posted by PurpleAardvark

Good exp. Just saw the price tag on that new 1080p 65" plasma $10,000. Since we are all such loyal BD fans here I know NYG is going to buy one for each of us at Christmas. 2 for me seeing how I don't get the free panny. Here is the link:

http://www.crutchfield.com/S-rV5QSx7...0&I=13365PX600

I'm guessing that is the new Panny. Absolutely ridiculous price tag. By the end of the year I bet the price is down 30%. Plasma needs to keep pace with LCD. I know this the minute Sony has a 60+ 1080P Bravia LCD for $5-$6k I'm all over it.

[BallsHD]

let's say you have two tvs: a 720p tv and a 1080i tv. if you set the resolution settings on both tvs to 1080i, is there any difference in PQ or sharpness or any of that jazz? thanks for posting in advance.

[Deciazulado]

When you say 1080i TV, you mean a true interlaced TV like a 1080i CRT or you mean a 1080 LCD (which display everything as 1080p) but only accepts a 1080i signal but not a 1080p signal?

I'll assume the later.

A 720 x 1280 display has a max. of 720 x 1280 pixels if it deinterlaces the 1080i correctly

It would have a max. of 540 x 1280 if it deinterlaces the 1080i with the cheapest method. That would be equivalent to about 624 x 1108 square pixels

A 1080 x 1920 display has a max. of 1080 x 1920 pixels if it deinterlaces the 1080i correctly

It would have a max. of 540 x 1920 if it deinterlaces the 1080i with the cheapest method. That would be equivalent to about 764 x 1358 square pixels


So depending on the deinterlacing chips on the displays they could go from both looking very similar, to the 1080 LCD looking up to 3 times as good.


another thread

[Rustolem]

I have a Mits WD-73727 and I sit about 12 feet away and I am watching my Samsung Blu-Ray via HDMI and at 1080i ( tv doesn't support native 1080p) so everyone is saying that there won't be a difference that would make you want to get a new native 1080p set ??? The difference from SD dvd to Blu-Ray 1080i is 100% better to me and I was watching my SD dvd's up converted to 1080i .

thanks

Rustolemite

[Deciazulado]

Originally Posted by rustolemite

I have a Mits WD-73727 and I sit about 12 feet away and I am watching my Samsung Blu-Ray via HDMI and at 1080i ( tv doesn't support native 1080p) so everyone is saying that there won't be a difference that would make you want to get a new native 1080p set ??? The difference from SD dvd to Blu-Ray 1080i is 100% better to me and I was watching my SD dvd's up converted to 1080i .

thanks

Rustolemite

Youre sitting at 4 Picture Heights (2.25 screen widths) from your 1.78 wide 36" x 63" (73" diagonal) screen.
You probably can see about 850 x 1500 pixels from there reaching the limits of your vision, maybe more if you have sharp eyes.

Your 1080i input is being deinterlaced to 1080p by your DLP panel I would assume.

If it's being deinterlaced correctly (and the optics of the TV are up to it) you should be getting the 1080 x 1920 pixels already.

But you might not be able to resolve them fully or with sharp contrast from your sitting distance.

(My advice: sit closer )



In the case you determine the 1080i input is being deinterlaced with the simplest bob method (540 x 1920), well there might be an 1.25x improvement if you had a 1080p input/1080p output TV (or a 1080i input/correctly deinterlaced 1080p output TV) from your sitting distance as you can see minimally 850 vertical now and you'd would be getting 540 vertical. (Horizontally you wouldn't see any difference, if your curren't TV resolves 1920 now. You see about 1500 of those anyway) So if your mits is bobbing 1080i, a true 1080p would look just one step sharper.

Still, my advice: sit a little closer


ymmv

[tmgrich]

Ive heard that the human eye shouldnt really be able to distinguish between 1080i and 1080p. I have found this to be untrue. I got the yamaha vx 2600 receiver and connected my samsung bluray player to the receiver via hdmi. I didnt know at the time the receiver didnt support 1080p but only 1080i. I immediately noticed that something was wrong with the picture and that it didnt look quite as sharp. So you can tell a difference.

[i want HD movies]

lol. that about sums it up. Maybe to put it simpler...
Depends...lol

If it is a 720/1080i set (I am assuming non-crt tube): the pixel count will be the same, usually 1368 x 768 whether it is a plasma or LCD panel.

If it is a True-HD, Full HD or 1080P set (all the same just depends on the company wording) then the pixel count will be 1920 x 1080, or double the 720/1080i set.

So it depends.

Also, as was said, depends on the quality of the set. For instance a Pioneer Elite at 720p looks better than some no name brand 1080P LCD set just due to the quality of the processing. Whereas a Sony XBR3 1080P LCD looks much better than, say, a HP plasma at 720P.