Home audio & video: Pixelation in HD content: The signal or the television?
Pixelation in HD content: The signal or the television?
by dgden - 12/12/07 10:41 AMI have a Sony XBR4 LCD HDTV and noticed that in some HD content there is visible pixelation especially in faster motion when I see pixely squares appear.
It is fairly minor and appears to be noticeable in some HD programming but not the other. Was watching Victoria Secret Fashion Show in HD, darn those girls look great in high def 
, and noticed a bit of pixelation when models walked down the runway.
I have not noticed it so much in other shows though, take Smallville in HD or Leno or Letterman (not much motion in talk shows though). I don't recall seeing it in a bunch of others as well.
This is actually one artifact that I really dislike and would like to know if this would be an issue with the content such as loss of some information in the signal, or is it the TV that is not able to keep up with the processing?
Is it something I would see on any HDTV or would it not be a problem say on the Plasma VS LCD?
Could I still see the pixely squares when wantching Blue Ray or HD DVD (I don't own either one)?
Thanks for the input!
ok well it not the broadcaster signal.
by gabereyes - 12/12/07 11:25 AM In reply to: Pixelation in HD content: The signal or the television? by dgdenI also watched Victoria Secret Fashion Show in HD on my HD CRT TV and I didnt see any pixelation, and I had it recorded on my DVR so I went back a few times to check. lol
Anyways if you dont see any pixelation on still or none motion pictures the picture settings on the TV should be fine, this maybe a LCD thing, you might try playing with the 120hz setting in the menu and see if it helps by turning it off or on.
As for HD channels the only one I seem to have a problem with is A&E channel and TBS channel and it not pixelation its just crappy color and sharpness.
hope this helps
good luck
gabe
What is your source Antenna or actual Cable?
by dgden - 12/12/07 12:35 PM In reply to: ok well it not the broadcaster signal. by gabereyesQuestion for you:
Do you get your HD through the air broadcast signal or was it through a digital cable box?
My TV is plugged in directly to the cable (no digital cable box) and the HD channels I pick up are the regural air broadcast HD, using the reciever built in to the TV.
In addition, I don't have a dedicated antenna plugged in, it just uses the cable itself as an antenna (hope this makes sense) and I actually don't even pick up all the HD availible in the area because of that.
What's your connectivity like?
All of the above
by gabereyes - 12/12/07 4:16 PM In reply to: What is your source Antenna or actual Cable? by dgdenI have Dish network as a full time service, but sence I have cable internet I hooked up basic cable straight to the TV, plus an off air antenna hooked throught the dish box for local HD channels.
I live in the midwest and with all the ice storms, I never know if one is working or not, so I figured if I have three types of service one is bound to work. lol
I did also have a cable box a couple of months ago, I just switched to dish so I did see it through a cable box too, but I dont see any diffrents from the box and going straight to the TV.
gabe
pixelation in HD
by magilla414 - 12/12/07 2:02 PM In reply to: Pixelation in HD content: The signal or the television? by dgdenthis problem is what has been keeping me from buying a new TV. Through all my browsing I noticed it on all LCD's and a slightly lesser extent on plasma's-in all price ranges. I have been told that this problem is only visible if you are sitting too close to the screen and is more apparent in the store. I'm glad someone mentioned having the problem in a home setting. I mostly watch sports, so it would drive me crazy to see constant pixelation during the action. Please let me know if you still see this effect (i heard it called the screen door effect) when sitting further away of if you find another solution. Thanks.
Screen door effect is a different thing...
by dgden - 12/12/07 2:51 PM In reply to: pixelation in HD by magilla414Pixelation is sometimes referred to as blocking, I believe. Screen door effect is something entirely different and is present (really) only on rear projection HDTVs.
My brother owns a Rear Projection LCD and I have an LCD HDTV. Now I know what people are talking about exactly when they say screen door effect. It's a percieved texture of a rear projection LCD screen (maybe DLP as well) which makes it look like you're watching a TV through a barely visible mosquito net, because the space between pixels is more apperent than on other technologies.
It's not nearly as bad as some people see it but it is a matter of perception.
A good example of a pixelation, on the other hand, would be a low resolution DivX movie, where you see the image starts to look like a jigsaw puzzle in fast motion.
What I have seen on my HDTV, is no where near as pronounced as on a low quality digital video. What is important to me, however, is a clear understanding on whether this is a limitation of a television set or a problem with the signal quality.
If you're a streaming a video through internet connection and some packets are lost, you will likely experience blocking of the image until the stream quality is restored.
I have seen opinions on the web claiming that this is a limitation of the video compression combined with a signal quality while other claim it's the TV.
Is this is a signal quality issue, it's not a problem as it will be improved as the TV world moves towards digital and HDTV. If this is a TV problem and I will see the pixelation even when watching Blue Ray, well that really sucks.
Technical knowledge on this anyone?
pixelizingscreen door effect,stair stepping,blocking
by dinox64 - 12/12/07 5:54 PM In reply to: Screen door effect is a different thing... by dgdenI have a Plasma and never once had that problem. Of everything I read and have read,never came across that happening on Plasmas. Now at work today, I did hear some guys talking about how Tv's today have built in boosters to bump up the low signals they receive,and that it sometimes gets shot back to the box and shows as noise on the screen. But that has nothing to do with the pixelating you're seen. That is the technology that goes with LCD and manufacturers can't get the refresh rate fast enough to correct it. They may sometime soon. It's just like the problems associated with Plasma when it first came out. Now burn in, too hot, bright rooms and short life are no longer factors. But it never had a pixelating problem,it's always been smooth and soft on the edges of its image.
I am not convinced...
by dgden - 12/13/07 10:56 AM In reply to: pixelizingscreen door effect,stair stepping,blocking by dinox64Since my purchase of LCD HDTV I've read quiet a bit of stuff, some technical and some not.
In my understanding, that most of the HDTVs including Plasma and LCD have a refresh rate of 60Hz (except the new 120Hz LCDs). Please correct me if I am wrong.
My LCD is actually 120Hz (Sony XBR4), which means it actually refreshes twice as fast as other HDTVs on the market be it plasma or regular LCD, so I do not believe the refresh rate is an issue here.
I've also seen posts when people said that pixelation is a signal issue and can be seen on both Plasma and LCD.
Once again, I don't know if that's true or not that's why I am hoping for more accounts and maybe a more professional explanation of why pixelation maybe seen.
1 millisecond (1 ms) is the cycle time for frequency 1 kHz .
by gabereyes - 12/13/07 9:26 PM In reply to: I am not convinced... by dgdenThe TV can do 120hz that equals 120 milliseconds.
But the LCD panel can only do 8ms response time, so the panel is getting sent 120hz but it cant keep up.
Meanwhile, plasma display's pixel response time is virtually instantaneous, limited only by the speed of the video processing
engine.
this is what might be causing the pixalation.
check out this link.
http://www.phctoys.com/Fujitsu_White_Paper_2005.pdf
I just found it, while I was looking for an answer for you.
good luck
gabe
Good info but still wrong :)
by dgden - 12/13/07 11:41 PM In reply to: 1 millisecond (1 ms) is the cycle time for frequency 1 kHz . by gabereyesThere was this really good post (too bad I didn't bookmark it) about the whole 120Hz and response times, but I understood. Here's a quote from the PDF you sent:
Many of today's larger LCD screens spec out at respose times that sometimes exceed 25ms - long enough to smear motion. Any response longer than 16 2/3 ms will smear TV's 60 fields-per-second video.
This only proves that response times of current LCDs are sufficient for the video signal and the math is consistent with the post I read. So 8ms response time is way plenty for a 60Hz refresh rate, actually twice faster than the required minimum of 16 2/3.
For 120Hz the required time would half of that which is 16.66666/2 is approx 8.33 which comes very close to the 8ms response time but is still sufficient.
So your argument is incorrect. And by the way, plasmas do suffer from phosphor lag, which has been reported by many video gamers. But let's not get into the whole Plasma VS LCD. I am just intersted in the pixelation side of things.
By the way, pixelation is not the same as motion blur.
I haven't seen any of those horribly slow refresh rate LCDs.
by NM_Bill - 12/14/07 8:19 PM In reply to: Good info but still wrong :) by dgdenYou seem very well informed yet you haven't nailed your pixelation problem. I got a rear projector, not Sony specifically because it had a picture that blended together well with no sign of pixelation whatsoever, that I objected to in typical plasmas at that time, four years ago.
ok sorry I didnt do the math.
by gabereyes - 12/15/07 12:25 PM In reply to: Good info but still wrong :) by dgdenMath gives me a head ache.
Im not sure what causes the pixelation, It could be signal and/or TV processing, maybe it has something to do with digital all together.
Here is what I have seen, any TV that is 100% digital, meaning the signal passes all the way to the image in digital form, I can always see some type of pixelation this is mostly on LCD, DLP, and micro projections sets.
as for any phosphor based TV like CRT, Plasma, and CRT projo, I dont see it in most cases.
and on my HD CRT tv I almost never see any pixalation, I would try getting an DVE calibration disc, and go through the moving test paterns to see if you get any pixelation, that should answer this tuff question.
I once heard that most phospher based TV's turn the digital HD signal back to analog RGB internally before processing and displaying the image, if this is true this could be the answer, but I dont know how much of this is true or not.
but it makes sence, its like a reciever taking a dolby digital sound track and tranfering the digital to analog using a DAC, this works very well for sound, why not video too.
P.S. if you find out if its the TV or the Signal please let me know.
gabe
Whoa there, Hoss!
by Dr. Planarian - 12/15/07 4:26 AM In reply to: 1 millisecond (1 ms) is the cycle time for frequency 1 kHz . by gabereyesThe item to which this is a reply is a very disinformative post.
120 Hz is NOT a 120 ms framing rate! 120 Hz comes out to an 8.3 ms refresh time. An LCD screen like the Sony XBR4's with a 4 ms latency can easily handle this. As far as I know, no commercially available television has a refresh rate faster than 120 ms.
This, however, has nothing to do with pixellation. Only a few of the most recently released television sets refresh this rapidly.
Television signals are sent at a rate of 30 frames per second. It doesn't matter what the source of the TV signals might be, whether over the air, through a cable, from a satellite provider, whatever. NTSC television pictures run at 30 fps. Always.
The advantage of 120 Hz is that it can also handle content from sources like Blu-Ray players capable of transmitting movies at their native 24 fps. The number 120 is evenly divisible by both 24 and 30, so no movie frames need to be repeated as each fifth one must be when shown on a regular 60 Hz television.
But none of this relates to pixellation in any way whatsoever.
Oops
by Dr. Planarian - 12/15/07 4:27 AM In reply to: Whoa there, Hoss! by Dr. PlanarianI meant to say, "As far as I know, no commercially available television has a refresh rate faster than 120 Hz (not ms).
Pixelation
by rsbruner - 12/14/07 7:31 PM In reply to: I am not convinced... by dgdenI have a SONY XBrR 1 and Panasonic Plasma TV. The only time I have ever experienced pixelation on either TV is through the OTA antenna. We have DISH Network, and the only time I have ever seen pixelation is when something was recorded on the DVR during a terrible storm - about 2 times a year. My parents have cable and a Sony rear projection LCos tv like myself and have no pixelation issues except for a dirty DVD. So it is not related to the TV technology - we also have had a Philips LCD TV that had no pixelation.
We have had screen door effect issues playing video games on the Plasma, but not as much on the LCD and not at all on the rear projection LCoS TV.
| Forum legend: | |
 |
Locked thread |
 |
Moderator |
 |
CNET staff |
 |
Samsung staff |
 |
Norton Authorized Support team |
 |
AVG staff |
 |
Windows Outreach team |
 |
Dell staff |
 |
Intel staff |
