Ask HD Beat: What's the deal with 1366 x 768?
Rob that is a great question and one that has come up many times before. I even asked the Pioneer representative at CES this year the same question. His response was that it was a PC resolution that has been standardized. He was of course talking about XGA which is 1024x768 but it is the same premise. More pixels is better, there is no arguing that, but the question still remains where do the rest of those pixels come from and how can they make a 16x9 display from a 4x3 resolution? The answer is actually pretty simple; it is not a 1:1 pixel mapping and pixels don't have to be square. In fact the Pioneer Elite plasma (arguably the best plasma) has a 1024x768 resolution and rectangular pixels.
I know what you are thinking now; How can it look as good if they are scaling the 1280x720 or 1920x1080 video to a different resolution? (Well that is what you should be thinking.) The answer is surprising or it at least is surprised me. All TVs scale, yes all! The single biggest difference between a TV and a computer monitors is that TVs have overscan. The reason isn't a good one, but that is the way it has always been and that is the way it is now. That means that if you buy a TV with a native resolution of 1280x720 and the TV has ~3% overscan, the circuitry in the TV is throwing away 3% of your pixels and scaling the rest to fit into the 1280x720 pixels on the display. There are some TVs that have the ability to turn this off, they call it "computer" mode others call it a 1:1 pixel map. The problem with theis modes is that TV production folks expect you to have overscan, so they use the outside pixels for things such as Closed Captions or Neilson ratings, it is refereed to in the industry as the vertical blanking interval. It also happens to be how those MovieBeam movies get beamed.
The bottom line is it really doesn't matter how many pixels your TV has as long as it looks good. If you are like me and your have an OCD for these type of things, buy a 1280x720 TV that you know has the ability to produce a 1:1 pixel map and ignore the garbage on the vertical blanking interval. If you are not brave enough to try it on your own, then there are ISF calibrated technicians who can do it for you.
















Reader Comments (Page 1 of 1)
Dan @ Apr 21st 2006 6:35PM
Great write up Ben :), Yeah overscan is nasty, I adjusted my tv for overscan and I think i got to about 2% it was originally around 5%, if I went anymore I really had some nastiness going on. Then the geometry issues were a headache. But I managed to get it looking pretty good with DVE. (I have a 30"sony CRT HD)
Alan @ Apr 21st 2006 7:12PM
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Bill @ Apr 21st 2006 7:24PM
Why 1366x768? It was easy. The first 'wide' panels that came out were true WXGA (Wide XGA) that were 1280x768. Fine and dandy for computer monitors, but the 15:9 aspect ratio didn't really work for TVs. The panel makers found it was easier (i.e. get more yield and make more money) to stretch it a little wider rather than cut off some vertical to get to 16:9. And that's how we got 1366x768.
As far as VBI data goes, if you see it, you are under-scanning. Also, you should only see this on SD feeds and all CC and other data is carried in the digital carrier of an HD feed, and not in the visual data.
--Bill
dozens @ Apr 21st 2006 8:30PM
As Bill mentioned above...I belive VBI is just an analog phenomenon. It should have little impact on your decision to overscan or not since most owners I know with highend HD sets watch very few analog channels.
Davor @ Apr 21st 2006 11:29PM
i am in market for TV and I dont want to buy 42 inch plasma because most of them are 1024 x 768 and as far as i know that is not full HD ot 720p so i am looking at LCD 37" to 42" so does that mean that i want see a big differnece in picture from 1024 x 768 to 1366 x 768?
Aaron @ Apr 22nd 2006 8:13AM
I have a 34" Panasonic CRT (CTWX15)that has some wicked overscan. My warranty would cover having a tech come and fix it, but I live in a rural area and they have no one that covers my area. Nice huh? Anyway, is there somewhere to find out how to get into the service menus and correct this myself?
Ben Drawbaugh @ Apr 22nd 2006 10:21AM
Bill,
I understand that VBI is just an analog phenomenon, but the fact of the matter is that it is real with HD as well. I have done many ATSC captures to my PC and I can see the line (usually green) on the end when watching HD in a window on my computer. I ran into a Neilson software engineer once and he confirmed that they were still encoding information into the VBI.
Thanks for the great comments.
Jake @ Apr 22nd 2006 10:27AM
Davor (currently #5):
1024x768 plasmas scales the 1280x720 signal to be displayed on the 1024 resolution and its rectangular pixels. The image you see is identical to what will be displayed on a 1366x768 panel, or a 1280x720 DLP. Go to any store displaying a 1366 LCD right next to a 1024 PDP and you will see immediately that there is no difference.
Jeff @ Apr 22nd 2006 11:27AM
IMHO - 1366x768 LCD panels look great at up to 37" size displays, and if the processing chipset is good, it will be a great experience... for 37" upclose to 40-52 living space type sizes though the 1080 resolution is the right thing.
720p is a square pixel format BTW, but get this, there are several pixel definitions for 1080, for example 1.333 ( for 1440 x 1080i TS stream ) is actually more typical than you may think, you could well be looking at a stream that has no square pixels in it at all and not realize it.
my biggest issue with 1366 displays is the scaler chipset may suck on getting a 1080i input and create a worse looking image than a 720p, no fault of the screen resoution, just the scaling engine technology.
Older samsung stuff can totally butcher an incoming 1080i compnent input stream for example, and generally you cannot tell that by relying on an In-Store viewing.
On the other hand the newest Dell 37" 1366 display is great at everything it does, and that is due in part to a superior processing chipset.
Great Processing will generate a progressive display of an incoming interlaced stream , and also scale the resolution to fit the the pixelspace of the display.
In general you want to see DCDi http://www.meridian-audio.com/faroudja/technology.html or FL2310 chips in the spec. Nvidia Pure stuff is good, as is CrystalScan.
Its best if the endpoint display processing is in the display itself, since that is the only way that engineers can tune the outcome to fit the properties of the display technology , be it LCD or DLP whatever.
Stu @ Apr 22nd 2006 4:24PM
Actually MovieBeam doesn't use VBI, it uses a proprietary RF technology from dotcast.com, it does however ride in the analog television broadcast. I think they transmit at 1mbps and VBI is only good for a max of around 128kbps.
josh @ Apr 23rd 2006 2:20AM
The bottom line is every fixed resolution display scales and if you can't see the pixel structure from where you are sitting, you don't need more of them. LCD is good for bright rooms and computer displays, Plasma is good for rooms with low to average light levels and video / HD.
You can spend a lot of time learning about the various numbers for each technoligy and brand, or you can do what smart people do and let your eyes and bugget be the judge.
Nice job Ben, you are one of the few people I talked with at CES that got there facts correct.
josh
jammypup @ Apr 25th 2006 1:14PM
Aaron, go here
http://www.avsforum.com/avs-vb/showthread.php?p=7292210&highlight=overscan#post7292210
then click on search within thread and search for overscan. It looks like someone did post details about getting into the service menu and adjusting for overscan but I don't have time to find the specific posts.
One I did look at had a nice pic iluustrating the o/s prob:
http://www.avsforum.com/avs-vb/showthread.php?p=7292210&highlight=overscan#post7292210
jasper vicenti @ Apr 25th 2006 9:06PM
I recently purchased a 32" LCD with 1366 x 768 resolution (Sony KDL-32S2000). I am kind of annoyed that I can't turn off the HD overscan, even after searching through the service menu. For the most part, I have my cable box output at 1080i rather than 720p for 2 reasons:
1. Most HD content available today is 1080i. I'd rather only downscale/deinterlace from 1080i -> 768p than have to downscale then upscale from 1080i -> 720p -> 768p. If I am watching something on abc, fox, or espn then I can manually change the comcast cable box to watch this program. They unfortunately do not allow HD passthrough, another annoyance.
2. Since there is overscan (2.75% according to the cnet review), 720p content is really scaled from 1245x700 whereas 1080i is about 1867x1021 (or even less, depending on the horizontal resolution).
I do notice that the image appears sharper when watching 1080i content.