720 vs. 1080 debate

Dennis Wood · April 22nd, 2005, 08:02 AM

Barry, perhaps you could explain your point. I was under the impression that 480i/1080i would have a temporal resolution of 60 samples per second, and 720 30p (or 480 30p) would have a spatial resolution corresponding to their actual measured frame resolution. Interlaced signals give higher temporal resolution than progressive, but less spatial resolution per frame. I'm assuming this is why interlaced footage makes for better slow mo.

With 480p, vertical resolution on the progressive frames is 33% higher than 480i interlaced frames due to losses incurred in row pair summation in the interlace process. If the same is true of 1080i, actual measured resolution should be somewhere around 1080-33% = 724 lines. Horizontal resolution, if displayed properly, would definitely be higher for 1080i over 720P as the same filter loss is not an issue....if the 1440 lines are actually displayed.

I sourced a paper copy of this article (“Understanding Camera Resolution,” Broadcast Engineering, August 1999)." which concluded that progressive resolution is almost twice that of interlace image resolution for moving objects.

If TV's are only displaying 1280 vertical lines, then I would theorize that 1080i and 720p should look pretty similar as far as resolution goes. If you are shooting 720 60p, then you now have the same temporal resolution and very similar spatial resolution to 1080i. If you take William E Glenn's findings into account then 720 60p should look "better" as far as our perception goes.

So how does this theory work out in practice?

Barry Green · April 22nd, 2005, 02:02 PM

Quote:

Originally Posted by Dennis Wood

So how does this theory work out in practice?

Exactly as you would expect. 720p and 1080i both look like "HD". A native 1920 signal being displayed as 1920x1080 does look sharper than a native 1440 signal being displayed as 1920. I wasn't talking about 720/30p, which isn't really shot or broadcast in the US, I was talking about 720/60p.

Of course, when talking about lower frame rates, the argument becomes absolutely moot. 1080/24p will stomp 720/24p all day long. 1080/30p will stomp 720/30p in every case. So the argument is relevant when comparing the full broadcast standards, 1080/60i vs. 720/60p. (or, when comparing NTSC or PAL against 720/60p).

What I was talking about is that I've seen *several* people posting that 720p isn't "really" HD, because it's only about 20% more lines than PAL. And that's just wacky talk. Because you have to take into account the higher refresh rate, plus because of the native progressive system, every pixel is individually discernible, you end up with 6x as many pixels per second of discernible pixels as opposed to a PAL system. And on NTSC, which is lower vertical resolution, it's more like 7x as many pixels.

Both 1080i and 720p end up pushing approximately 60 million pixels through the TV set every second. 720p doesn't suffer from resolution loss due to interlacing, and it updates a full frame rather than a half-size field. Both provide for the "reality" look by providing 60 updates per second, but while 1080 updates half its frame vertically, 720 updates its entire frame.

My point isn't that one is better than the other, the point is that they're both fully legit "HD", and that the overall viewing experience is quite comparable between the two.

Dennis Wood · April 22nd, 2005, 10:21 PM

Goes to show how much I know about HD...I was under the incorrect impression that 720 30p (not 60p) was the standard. So your point is well taken...sounds like 720 60P is pretty much the equivalent of 1080i. I've had a 51" Sony HDTV for 3 years now...it's never seen actual HD yet :-(

Brandon Greenlee · April 23rd, 2005, 08:32 AM

So at what point are most tv's going to be capable of displaying 1080i and/or 1080p?

Is this still a while off?

Kevin Shaw · April 23rd, 2005, 08:49 AM

Brandon: many inexpensive rear-projection HDTVs are theoretically 1080i displays, but I've seen comments to the effect that even this may be a bit of a technological trick. And I think there are some HDTV projectors now which have true 1080p resolution, but those are not something which will be widely used by consumers any time soon. Per my earlier post, the current trend seems to be toward digital displays which are mostly 720p or lower resolution, because 1080p displays are too expensive to produce for now.

In any case, it's currently much easier to distribute HD content at 720p resolution than at either 1080i or 1080p, so when you add all this up 720p makes sense as today's best delivery format. 1080p would obviously be better, but by the time that becomes practical there will be tens of millions of 720p and 1080i displays in use which people are not going to rush to replace. As far as I'm concerned, 720p will be the preferred output standard for the next several years, even if 1080i delivery options become more commonplace.

Steven White · April 23rd, 2005, 09:19 AM

So at what point are most tv's going to be capable of displaying 1080i and/or 1080p?

A lot of the HDTV CRTs, like the 34" ones from Toshiba and Sony are 1080i native displays. Some of the rear-projection CRTs are 1080i as well. I don't think many of the DLP and LCD projection type displays or the Plasma/LCD panels are there yet - most reside in the 1280x768 resolution. There are a few 1920x1080 displays coming out in the $10k + market (Sony has an 1920x1080p projector for $30k)... but it seems like the display manufacturers are looking to get to 1080 native displays soon.

Barry Green · April 23rd, 2005, 02:43 PM

I've got one of those Sony 34" XBR sets, and native 1080 is indeed spectacular on it, as is native 720. Both formats look incredible on this CRT.

However, one glance at the offerings at Best Buy, Circuit City, etc., will let you know: consumers don't want CRTs. The vast majority of sets on display are flat panels (whether plasma or LCD, etc.) And those type of sets have discrete pixels, so they'll be optimized for one resolution or the other. Right now, most of them are optimized for 720p (although there are some 1024x1024 plasmas out there! And plenty of them are actually EDTVs, with a resolution of 864x480).

Dell has the 2405FPW flat-panel LCD computer monitor which is 1920 x 1200; a tiny bit of letterboxing gets you 1920x1080. More will be forthcoming.

Khoi Pham · April 23rd, 2005, 02:51 PM

"So at what point are most tv's going to be capable of displaying 1080i and/or 1080p?"

3 more months.
Go to this link
http://www.weva.com/cgi-bin/newsread...o&storyid=2427

Steve Crisdale · April 23rd, 2005, 05:42 PM

Quote:

Originally Posted by Khoi Pham

"So at what point are most tv's going to be capable of displaying 1080i and/or 1080p?"

3 more months.
Go to this link
http://www.weva.com/cgi-bin/newsread...o&storyid=2427

Boy is that being overly optomistic or what!!! I'd suggest the true answer to the question of when MOST TVs are going to be capable of native 1080i/p is a hell of a lot further off...

Sure there have been demonstrations of native 1920x1080 resolution panel, but the purchase price for the immediate future - and that's at least 3 months, is astronomical. That sort of rules out mass take up of native 1080i/p display devices for an indeterminate period beyond 3 months.

Given that the current state of play indicates there isn't anywhere near market saturation by the current breed of HDTVs, why in the name of sanity would most HD TVs being watched in 3 months time, be the sort that are today, only available to a select and privileged few?

Steven White · April 23rd, 2005, 05:56 PM

Well "most TV's" is wrong... but I disagree that the price will be astronomical. The DLP technology is one of the cheapest ways to get half-decent HD displays. While the 1920x1080 plamas are going to be extremely expensive, the projection technologies are a lot more efficient and simpler to manufacture. The reasons I haven't bought an HDTV yet is because

a) I don't have room for a 34" CRT (the depth is just too big)

and

b) None of the plasmas or DLP projection DVs have been 1920x1080p. There's no way I'm buying a TV that isn't native to what my camcorder puts out.

Khoi Pham · April 23rd, 2005, 06:45 PM

Oh yeah, I meant there will be much more to choose from in 3 months, not most tv will be it 1080p, right now there is only 2 to choose from.

Steve Crisdale · April 23rd, 2005, 07:57 PM

Quote:

Originally Posted by Steven White

Well "most TV's" is wrong... but I disagree that the price will be astronomical. The DLP technology is one of the cheapest ways to get half-decent HD displays. While the 1920x1080 plamas are going to be extremely expensive, the projection technologies are a lot more efficient and simpler to manufacture. The reasons I haven't bought an HDTV yet is because

a) I don't have room for a 34" CRT (the depth is just too big)

and

b) None of the plasmas or DLP projection DVs have been 1920x1080p. There's no way I'm buying a TV that isn't native to what my camcorder puts out.

So you wouldn't buy a current device that may well do an outstanding job of scaling 1080 to the devices native resolution? What if the prices of a good scaling HDTV meant that you could at least enjoy what's currently available right now, while waiting for the 1080 native sets to infiltrate the market?

My 2c's worth.... I'd much rather enjoy seeing my FX-1e clips on my Sharp Aquos LCD HDTV, than waiting for something that may not look heaps better... and if it does, I'll buy a 1080 native set when they're cheap enough..

While we may feel like the world of HD technology is advancing at breakneck speed (which still isn't fast enough for some!!), for the 'Average Joe', they couldn't give two craps whether they had native 1080 or not.... They just want a TV set that will 'work'. No need to do anything other than turn the bludger on and watch the pretty pictures.

When 'Average Joes' dip their toes into buying a new TV, they'll buy something affordable, that works now and with PQ that looks good to their eyes.

So, while it's nice to dream of where this technology appears to be heading and how soon, I'd prefer to be a little cautious. Retailers sure ain't gonna love some-one telling them to trash all their current stock, just to replace it with the next "big thing". The financial bottom line is what drives corporations in this level of technology. I'm sure they really don't want to see their investment in 720i/p capable devices with 1080 scaling just vanish before their eyes.

Steven White · April 23rd, 2005, 08:33 PM

So you wouldn't buy a current device that may well do an outstanding job of scaling 1080 to the devices native resolution?

Hm... let's check out my current current system:

http://s94963366.onlinehome.us/HDRFX1/spiffsetup.jpg

Eek. I guess the answer is a definitive "no" considering my 13" television hasn't even been upgraded to a halfway decent SD CRT. I can wait. I can usually settle for pure crud until I'm sure I'm getting exactly what I want.

Ken Hodson · April 25th, 2005, 12:30 AM

Considering you settle for that, any 720p TV should exceed all of you expectations for the next 20 years. I see you had no problems adapting to modern sound HD.

Kevin Shaw · April 25th, 2005, 06:53 PM

"you could take a VHS image and interpolate it up to 1080i, and say it's a high definition image..."

You could, but that would be fraudulently deceitful, since it wouldn't contain an HD level of source detail. However, some videographers have already threatened to do just this to try to get around having to buy any kind of HD camcorder. Bad idea.

"I think the factor that outweighs 720p or 1080i is the ability of the camera operator and the controls of the camera they're working with. Indeed, these factors can also bring the quality of DV above any HD format, if you've put a good DV camera with great controls in the hands of an expert, and the HD camera is being operated by a lesser person. "

While that's ultimately true in terms of the content, I doubt anyone will confuse SD source material with HD/HDV source when played on a proper HDTV display. Or to put this another way, does anyone here really believe that you could pass off a 640x480 still image when compared side-by-side with a 1920x1080 still image? For any subject with any real detail it it?

April 23rd, 2005, 08:32 AM	#34
Brandon Greenlee Major Player Join Date: Dec 2004 Location: North Alabama Posts: 242	So at what point are most tv's going to be capable of displaying 1080i and/or 1080p? Is this still a while off? __________________ Brandon Greenlee

April 23rd, 2005, 02:51 PM	#38
Khoi Pham Major Player Join Date: Nov 2004 Location: Dallas Posts: 747	"So at what point are most tv's going to be capable of displaying 1080i and/or 1080p?" 3 more months. Go to this link http://www.weva.com/cgi-bin/newsread...o&storyid=2427 __________________ Khoi Pham www.proeditproductions.com

April 23rd, 2005, 06:45 PM	#41
Khoi Pham Major Player Join Date: Nov 2004 Location: Dallas Posts: 747	Oh yeah, I meant there will be much more to choose from in 3 months, not most tv will be it 1080p, right now there is only 2 to choose from. __________________ Khoi Pham www.proeditproductions.com

April 25th, 2005, 12:30 AM	#44
Ken Hodson Trustee Join Date: Aug 2003 Location: Vancouver BC Canada Posts: 1,315	Considering you settle for that, any 720p TV should exceed all of you expectations for the next 20 years. I see you had no problems adapting to modern sound HD. __________________ Damnit Jim, I'm a film maker not a sysytems tech.

April 22nd, 2005, 08:02 AM	#31
Dennis Wood Major Player Join Date: Mar 2005 Location: Ontario, Canada Posts: 916	Barry, perhaps you could explain your point. I was under the impression that 480i/1080i would have a temporal resolution of 60 samples per second, and 720 30p (or 480 30p) would have a spatial resolution corresponding to their actual measured frame resolution. Interlaced signals give higher temporal resolution than progressive, but less spatial resolution per frame. I'm assuming this is why interlaced footage makes for better slow mo. With 480p, vertical resolution on the progressive frames is 33% higher than 480i interlaced frames due to losses incurred in row pair summation in the interlace process. If the same is true of 1080i, actual measured resolution should be somewhere around 1080-33% = 724 lines. Horizontal resolution, if displayed properly, would definitely be higher for 1080i over 720P as the same filter loss is not an issue....if the 1440 lines are actually displayed. I sourced a paper copy of this article (“Understanding Camera Resolution,” Broadcast Engineering, August 1999)." which concluded that progressive resolution is almost twice that of interlace image resolution for moving objects. If TV's are only displaying 1280 vertical lines, then I would theorize that 1080i and 720p should look pretty similar as far as resolution goes. If you are shooting 720 60p, then you now have the same temporal resolution and very similar spatial resolution to 1080i. If you take William E Glenn's findings into account then 720 60p should look "better" as far as our perception goes. So how does this theory work out in practice?

April 22nd, 2005, 10:21 PM	#33
Dennis Wood Major Player Join Date: Mar 2005 Location: Ontario, Canada Posts: 916	Goes to show how much I know about HD...I was under the incorrect impression that 720 30p (not 60p) was the standard. So your point is well taken...sounds like 720 60P is pretty much the equivalent of 1080i. I've had a 51" Sony HDTV for 3 years now...it's never seen actual HD yet :-(

April 23rd, 2005, 08:49 AM	#35
Kevin Shaw Inner Circle Join Date: Sep 2004 Location: Sacramento, CA Posts: 2,488	Brandon: many inexpensive rear-projection HDTVs are theoretically 1080i displays, but I've seen comments to the effect that even this may be a bit of a technological trick. And I think there are some HDTV projectors now which have true 1080p resolution, but those are not something which will be widely used by consumers any time soon. Per my earlier post, the current trend seems to be toward digital displays which are mostly 720p or lower resolution, because 1080p displays are too expensive to produce for now. In any case, it's currently much easier to distribute HD content at 720p resolution than at either 1080i or 1080p, so when you add all this up 720p makes sense as today's best delivery format. 1080p would obviously be better, but by the time that becomes practical there will be tens of millions of 720p and 1080i displays in use which people are not going to rush to replace. As far as I'm concerned, 720p will be the preferred output standard for the next several years, even if 1080i delivery options become more commonplace.

April 23rd, 2005, 09:19 AM	#36
Steven White Major Player Join Date: Nov 2004 Location: Canada Posts: 547	So at what point are most tv's going to be capable of displaying 1080i and/or 1080p? A lot of the HDTV CRTs, like the 34" ones from Toshiba and Sony are 1080i native displays. Some of the rear-projection CRTs are 1080i as well. I don't think many of the DLP and LCD projection type displays or the Plasma/LCD panels are there yet - most reside in the 1280x768 resolution. There are a few 1920x1080 displays coming out in the $10k + market (Sony has an 1920x1080p projector for $30k)... but it seems like the display manufacturers are looking to get to 1080 native displays soon.

April 23rd, 2005, 02:43 PM	#37
Barry Green Barry Wan Kenobi Join Date: Jul 2003 Location: North Carolina Posts: 3,863	I've got one of those Sony 34" XBR sets, and native 1080 is indeed spectacular on it, as is native 720. Both formats look incredible on this CRT. However, one glance at the offerings at Best Buy, Circuit City, etc., will let you know: consumers don't want CRTs. The vast majority of sets on display are flat panels (whether plasma or LCD, etc.) And those type of sets have discrete pixels, so they'll be optimized for one resolution or the other. Right now, most of them are optimized for 720p (although there are some 1024x1024 plasmas out there! And plenty of them are actually EDTVs, with a resolution of 864x480). Dell has the 2405FPW flat-panel LCD computer monitor which is 1920 x 1200; a tiny bit of letterboxing gets you 1920x1080. More will be forthcoming.

April 23rd, 2005, 05:56 PM	#40
Steven White Major Player Join Date: Nov 2004 Location: Canada Posts: 547	Well "most TV's" is wrong... but I disagree that the price will be astronomical. The DLP technology is one of the cheapest ways to get half-decent HD displays. While the 1920x1080 plamas are going to be extremely expensive, the projection technologies are a lot more efficient and simpler to manufacture. The reasons I haven't bought an HDTV yet is because a) I don't have room for a 34" CRT (the depth is just too big) and b) None of the plasmas or DLP projection DVs have been 1920x1080p. There's no way I'm buying a TV that isn't native to what my camcorder puts out.

April 23rd, 2005, 08:33 PM	#43
Steven White Major Player Join Date: Nov 2004 Location: Canada Posts: 547	So you wouldn't buy a current device that may well do an outstanding job of scaling 1080 to the devices native resolution? Hm... let's check out my current current system: http://s94963366.onlinehome.us/HDRFX1/spiffsetup.jpg Eek. I guess the answer is a definitive "no" considering my 13" television hasn't even been upgraded to a halfway decent SD CRT. I can wait. I can usually settle for pure crud until I'm sure I'm getting exactly what I want.

April 25th, 2005, 06:53 PM	#45
Kevin Shaw Inner Circle Join Date: Sep 2004 Location: Sacramento, CA Posts: 2,488	"you could take a VHS image and interpolate it up to 1080i, and say it's a high definition image..." You could, but that would be fraudulently deceitful, since it wouldn't contain an HD level of source detail. However, some videographers have already threatened to do just this to try to get around having to buy any kind of HD camcorder. Bad idea. "I think the factor that outweighs 720p or 1080i is the ability of the camera operator and the controls of the camera they're working with. Indeed, these factors can also bring the quality of DV above any HD format, if you've put a good DV camera with great controls in the hands of an expert, and the HD camera is being operated by a lesser person. " While that's ultimately true in terms of the content, I doubt anyone will confuse SD source material with HD/HDV source when played on a proper HDTV display. Or to put this another way, does anyone here really believe that you could pass off a 640x480 still image when compared side-by-side with a 1920x1080 still image? For any subject with any real detail it it?