Hi, I get the difference between 720 and 1080p resolution, but I dont understand why 720p even exists. The salesman told me that when they went to bigger screen size they needed more pixels because the spacing between the pixels was getting to far apart. So they doubled the rez and 1080p was born. The thing is I want a 32" and just about all of them are 720p. I know there are some at 1080p but at almost twice the price. Why have 720p? When color came out we didnt have full color and half color. What Im afraid of is when I get a 720p they will finally find away to broadcast 1080p and Ill have to get a new tv. I know its a bandwidth problem now but not for long I bet. I have also heard not many tv's can correctly de-interlace a 1080i signal to 720p now so I think this could be a problem. What do you guys think?

720p exists because of the ATSC standard, which defines what resolutions HD broadcasts can be in. There are a number of resolutions included in that standard, but the two that everyone uses are 720p and 1080i. When folks started building HDTV's, the early LCD, plasma, and DLP solutions became very expensive if they were built to operate at that 1080 resolution (1900x1080 pixels), so it became common to do a reduced resolution (768 "lines") to be more cost effective. On smaller displays, this has continued and will likely still do so for some time to come, because the cost premium to build a 32" 1080p LCD flat panel is significant without offering an appreciable benefit over 768p at typical viewing distances.

I'll offer a few random observations about shopping for a 32" TV right now. First, HD broadcasts will mostly stay at 1080i, and the few that go to 1080p will simply be deinterlacing 1080i or scaling 720p in almost every case - 1080p content will be scarce. Second, all HDTV's have to be able to scale and deinterlace. Sure, some are better at it than others, but they all need to be able to accept a 480i, 480p, 720p, or 1080i signal (and in most cases today a 1080p signal as well) and manipulate it to the native resolution of the display. As a result, broadcasting at 1080p will not make 720p displays obsolete. The only difference between broadcasting at 1080p and at 1080i is that 1080p means your TV doesn't have to do any deinterlacing. Since the scaling process is easier (relatively speaking) than deinterlacing, it's hard to say that you are losing anything.

As far as I know 1080p is not part of the broadcasting standards for HD, so don't expect it to come out of your cable or satellite box anytime soon. It would have to be 1080p 60fps to make a difference anyhow as you will have a very hard time telling the difference between 1080p 30fps and 1080i 30fps (which is the max that 1080i will do using 60 half frames a second).

They did not start making 1080i sets because they reached limits of 720p display technology. 720p and 1080i have always been a part of the HDTV spec. The older generation CRT HDTVs were all capable of handling 1080i (a lot were not capable of displaying 720p natively at all though).

I'd also like to say that for a 32" TV you'd have to sit very close to get the full detail of 1080i (4' in fact according to my favorite distance calculator http://myhometheater.homestead.com/viewingdistancecalculator.html). So unless you are planning to sit that close, you won't need a 1080 display.

Having said that, and being the owner of a 50" display that I'm sitting 7-8' away from, you can never get big enough. Go with the largest display that you can afford and that fits your space.

32" is not that big for a 16:9 display.

Actually, there is one satellite service now being pitched as providing 1080p. It has the same bandwidth limitations as any other, though, and the ads I've seen don't mention compression algorithms being used to tell how much squeezing they're doing.

They can claim all they want and perhaps it's possible that they are broadcasting at 1080p/30 for movies, but there's no broadcast or cable TV recorded in that format, so any regular TV will be the same on a 1080i set vs a 1080p set.

Also as far as practical matters go, 1080p/30 is the same thing as 1080i/60(60 half frames per second).

About the only time I've heard of 1080p holding an advantage is for some PS3 games that are displayed/rendered at 1080p/60, which cannot be done through 1080i.

BloggingITGuy your link for your favorite calculator did not work. I found myself re-directed to some web page development site.

Yeah, the ")." at the end got added. Try this http://myhometheater.homestead.com/viewingdistancecalculator.html

That worked. Thanks BloggingITGuy.

Isn't 720p superior to 1080i???...I thought if the native resolution was 720p it was just that whereas 1080i was doubling 540 (to get to 1080i)...have I got this wrong???...I can get both 10801 and 720p but can't see a whole lot of difference...
...also, should I be holding off on BluRay if I have a 720p/1080i set (50" rear screen projection Sony)
Bill

The opposite, actually - 1080i has more pixels than 720p, it just redraws them differently (each pixel gets redrawn 30 times in a second rather than 60 times).
The 1080/540 thing you are thinking of may be related to the early 1080 rear-projection displays, back when 720p (or, more exactly, 768p) was the standard - if I remember correctly, they weren't able to put enough pixels on a chip to do 1080 lines, so they did 540p and used that to draw 1080i by alternating. It's been a while since I looked at that issue, though.
I'll counter with a similar question: should I have held off on buying DVD until I had a TV with component video inputs? In both cases, I would answer "no" - in the case of Blu-ray, you have an HDTV and it will give you the best picture it possibly can if you feed it a true HD source. Just because the best results in your case may come from scaling down to 720p output doesn't mean you shouldn't do it.