How bad should a plasma look

Forums › Home Theatre (including HTPC and EPG Collector) › How bad should a plasma look - P46U20Z

richms

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#63600 30-Jun-2010 17:40

Flatmate got one, and it has horridly bad dithering visible on it, even the default windows 7 background is all noisy, and thats over HDMI, as is freeview and the wii on component on it.

I havent seen dither that bad since a really old 42" SD samsung. How do others find theirs? At 2.5m from it, IMO its unwatchable with it expecially in the darker areas.

The panasonic site says 6,144 Equivalent Steps of Gradation for it, so I dont really see how it could be this bad and get described as that.

When putting up some graduation bars on it from the PC, the lowest one gets a small number of really really bright pixels lit in it, the next bar more, etc as you would see if you had for example taken the image and turned it into a websafe pallet, except its moving.

Any options that may help with this or should he look at sending it back and getting an LCD since they dont seem to have this problem?

Richard rich.ms

Dingbatt

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#346785 30-Jun-2010 21:24

I was going to ask what resolution you were feeding it from your PC as it is a 1080p full HD panel but then I saw you had trouble with freeview and Wii as well. Sounds like a 'friday afternoon/monday morning" panel that isn't up to spec.

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Jaxson

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#346897 1-Jul-2010 10:08

What additional screen 'enhancement' options have you got turned on/off?

mentalinc

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#346913 1-Jul-2010 10:33

Have a read of this, sounds similar to your issue
http://www.geekzone.co.nz/forums.asp?ForumId=84&TopicId=46736

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richms

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#347009 1-Jul-2010 15:12

Its happening on the inbuilt freeview as well. Changing the brightness does not change the brightness of the dots, so its quite apparent that the brightness control is scaling the video before this problem occurs.

The only changes have been sharpness down to 0, and the 16:9 over scan turned off. It is delivering a 1:1 pixel mapping from the PC now with the gamma looking perfect.

PC is outputting 0-255 and the screen is set to accept it, can clearly see the difference between 0 and 1 on the colour bar tests because 1 has the presence of the quite bright snow in it, whereas 0 is dark. Can also see a difference between 255 and 254 although its just a variation in the noise that is in the pixel.

with the panel having a 600Hz rate, I would have thought that any dither would be moving so fast that it was not visible, this is really obvious.

If I can I will try to get some pics of the problem tonight.

Richard rich.ms

Masterpiece

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#347102 1-Jul-2010 20:59

Just some key things to consider.

All Plasma panels can have some noise at low luminance levels.
All Plasma panels with lower power drive systems will struggle to control full field rasters at higher luminance values. This is design, as generally only parts of an image is at high luminance, and also because luminance is log as our vision we do not percieve a lowered luminance level when the drive limits are reached.
At low luminance it is hard for pixels to hold such small changes and results in noise.

This is important, generally video images are moving, here you are viewing fixed images...which may incedentally have induced noise created by the source which includes noisey (electrical) power supplies of things such as PC's.

Electrical noise, can induce noise into a display system or audio system. Isolation is key to checking this out. A fridge in another room could cause visual noise, with that an electrically noisey device anywhere in the house or connected somehow, through mains supply, eithernet, audio loops, device earth loops and the list goes on can cause issues.

Ultimately the cause may be elusive, or it can be normal, really asking techy ppl may induce answers as shugged shoulders "it depends" and "dunno".

Btw video is still currently 16~235, PC signal is 0~255, so set output for video to 16~235, for gaming 0~255. The TV doesn't care that much excepting that black and white levels may be incorrectly set as a result.

Source noise, this is common, induced digital noise is harsh when a imagery display device accurately portrays the information it is given. Basically panels are far better than they ever have been, bad data once lost through limited displays hid the noise.

Crappy cables...."groans from all corners"....however be cautious with AD DA connections, the result can carry through into the device even if not in use, ie watching the built in freeview.

What about the UHF signal and connected cables?

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richms

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#347161 2-Jul-2010 00:15

Looked at another one in a shop today, just as noisy so its not a problem with the TV.

Really nice picture on it when ages away from it, but when at a distance where a 46" is sane, its too clearly visible and distracting.

Does it on the inbuilt freeview, with nothing else connected. when watching survivor it was very apparent where the end of each colour appearing in the sky was, thats digital so no cable or noise issues there. Changing the brightness on the TV moved the ends of each area so again, clear its not in the source material.

Richard rich.ms

Masterpiece

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#347198 2-Jul-2010 09:11

The trouble with this discussion is it's a bit like phoning a car mechanic and telling him your car makes a funny noise.

Btw shop setups are not that great an example, typically very electrically noisey environments and you see grain and noise in images, especially plasmas.

If your flatmate is really concerned about the panel, contact Panasonic or the retailer he purchased it from, I'm sure you will secure a better result than getting too wound up chasing your tail from ideas here.

btw setting 1:1 pixel mapping is generally a good idea, however setting sharpness to 0 ?
You could and can create artifacts setting this incorrectly.

Have you also tried any of the anti noise features?

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ET: "Maybe; you have some freewill, but you chose your path by arrangement"

Me "That sounds like a program with no freewill?"

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Me: .....

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Jaxson

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#347216 2-Jul-2010 10:09

Any pics?

richms

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#347341 2-Jul-2010 16:21

No, he wasnt here last night and im not going to go messing with his computer to get the test images up. prob tonight will be able to get some.

Richard rich.ms

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#347552 3-Jul-2010 19:42

richms:

with the panel having a 600Hz rate, I would have thought that any dither would be moving so fast that it was not visible, this is really obvious.

As an aside - the 600Hz sub-field drive is only available when the panel is set to Cinema Mode.
Also... why do you have sharpness set to zero?

richms

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#347560 3-Jul-2010 20:16

Because otherwise it has obnoxious edge enhancement when using it on the PC as is evident by putting up a grey bar test that gets progressively worse as it gets tighter. PC monitors never have sharpness on them because you expect a 1:1 mapping, I don't know why TVs have it, and have the stupid default of half way.

Will try it on cinema when the flatmate is back and doesnt have company over.

Richard rich.ms