W510 Screen flickers when showing grey gradient

W500/510/520 and W700/710 series specific matters only
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Jih
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W510 Screen flickers when showing grey gradient

#1 Post by Jih » Sat Mar 13, 2010 4:47 pm

I posted the same topic on NBR but with no real answers. Just posting it here to see what you guys think.

Source: http://forum.notebookreview.com/showthread.php?t=465708
Hey guys,

Any of you having a screen flickering problem when displaying grey?
Here is a link to someone with a similar problem (and an example image).

http://www.nvnews.net/vbulletin/showthr ... ?p=2195382

example image:

http://www.nvnews.net/vbulletin/attachm ... 1267046502

On the W510 do you know if there is a simple solution to this problem?

Thanks.
Mutnat wrote:I'm not seeing it at all. It flickers a tiny bit when I drag it around the screen, but as soon as I stop and leave it in one place, it is stable and free of flicker. I wonder if it's something to do with the discrete graphics adapter on the W510?

On a releated note: I did notice some backlighting uniformity issues when dragging the image around. The bottom half appears quite a bit lighter in colour when near the center of the screen, and darker when near the far left or right sides of the screen. On the other hand, if I set that image as my desktop wallpaper, tiled, and minimize all windows, I can't really see the backlighting uniformity issue. So it could be some weird alpha-blending issue, perhaps?
Now that you mentioned it, I downloaded the image and opened it with windows live photo gallery. There is less but still noticeable flickering when compared side-by-side with the image loaded in Firefox 3.6.

I do not notice the uniformity issues when moving the image around.

When the image is set as the wallpaper (tiled) my screen is going crazy with the amount of flickering happening!
:)

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Re: W510 Screen flickers when showing grey gradient

#2 Post by QFoam » Sat Mar 13, 2010 10:40 pm

Jih wrote:I posted the same topic on NBR but with no real answers.
That's because the people over there aren't as smart as the people over here. ;-)

Most LCD displays are susceptible to this issue. You just have to provide the right situation for the flickering to become visible. See:

http://www.lagom.nl/lcd-test/inversion.php#invpattern
(do NOT run this test if you suffer from epilepsy, and I'm not joking)

See the "Background" section at the bottom of that page for an explanation. On my W700 w/1920x1200 400nit display, box 4b flickers ever so slightly (or sometimes box 4a instead, depending on its screen position), especially if I look at it through the corner of my eye. The flickering is much more pronounced in the full-screen test, where I also see some flickering of 2b.

The gradient that you link to in your post looks fine on my display, with no noticeable flicker.

So what you may be seeing, if you look at that gradient (or any other image) and see flicker, is an interaction between a dithering pattern and the interleaving pattern of your monitor. The dithering pattern could either be encoded in the image itself (i.e. the pixels in the image file contain dithered values), or else it could be introduced by your video card during the display process.

I just blew up that gradient image in Photoshop so that it filled my screen. Then I thresholded it, slowly changing the threshold from 0 to 255, in steps of 1. I did notice a lot of dithering along the vertical direction in the bottom half of the image. So if you're seeing flickering there, it's probably due to dithering encoded into that image itself. In other words, the flicker is due to the special construction of that image (whether intentional or accidental), just as with the flickering you see at the test page on lagom.nl.

If you instead see flickering in images that don't have dithering encoded into them, then you may be seeing an interaction between the dithering pattern being used by your video card and the interleaving pattern of the monitor. If such flickering becomes too objectionable, then you may have a dithering setting somewhere in your nvidia control panel (or a setting in the device manager for your video card, or in a .conf/.ini file) that lets you change the display card's dithering pattern, hence reducing the flicker.

In any case, seeing the above flickering in images you encounter on a daily basis is probably extremely rare.
Last edited by QFoam on Sun Mar 14, 2010 12:18 am, edited 9 times in total.
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Jih
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Re: W510 Screen flickers when showing grey gradient

#3 Post by Jih » Sat Mar 13, 2010 11:09 pm

That's a cool site!

I flicker on 2a (lots), 4a (lots), and 4b (medium)

FYI: HD+ screen W510

Puppy
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Re: W510 Screen flickers when showing grey gradient

#4 Post by Puppy » Mon Apr 05, 2010 1:15 pm

Another reason might be that you are sensitive to the FRC technology (http://en.wikipedia.org/wiki/TFT_LCD#Tw ... c_.28TN.29) which cycles two colors of a pixel to simulate more than poor 262144 colors a TN panel can display only. Depending on the panel vendor the effect might be more or less annoying. BTW make sure you have selected "Color quality: Highest (32 bit)" in display options. Lenovo sometimes defaults it to 16 bit only which makes it even worse in some cases.
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Re: W510 Screen flickers when showing grey gradient

#5 Post by zenit » Tue Apr 06, 2010 12:23 pm

W510 FHD, flickers as well. On grays and other "in between" colors. For some reason its particularly bad on newegg website's beige background. Slight shimmer is also noticible in blue background of Word 2007.

I might be parcticularly sensitive to this, but i notice the flicker on off-colors on all LCD displays including my 8bit S-IPS desktop monitor. Back in CRT days i had to jack up the refresh rate extremely high as well to not notice the CRT flicker. The W510 FHD screen is more sensitive to this "pixel-walk" than others, however the representation is not nearly as bad. On older T400 it didnt flicker, but rather had diagonal lines running in synch over an area of off-color. Same thing on alot of the screens Sony uses. Ironically, the only screen without any flickers i've used in the past was the terrible T400s panel. Maybe because it doesnt even attempt to reproduce colors accurately?

Some people say that at least on Sony laptops this flicker and running lines are made worse by the anti-glare coating on the screen due to some polarizing effect.
People reported similar stuff when applying an anti-glare material to glassy screens on macbook pros. So really anythhing can be causing this, from dithering to anti-glare coating
artifacts to mal-adjusted voltage that is supplies to the panel.

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Re: W510 Screen flickers when showing grey gradient

#6 Post by Chatbox » Sat Nov 20, 2010 2:47 am

Seems like the majority of LCDs on the market (for laptops and for desktops) do at least flicker on 1 of the tests. I'm currently in the Apple store in Sydney, and just tested the 13inch MacBook Air. It suffers from screen flicker on test 4b.

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Re: W510 Screen flickers when showing grey gradient

#7 Post by QFoam » Sat Nov 20, 2010 3:36 am

Chatbox, also turn down the brightness of the display, and see if you notice any flickering. Manufacturers control brightness on LED-backlit displays by varying duty cycle of the backlights, which can cause flickering if not done properly.

Thinking of moving to the dark side, eh? Or maybe Apple is the bright side, nowadays. In any case, good job with the W510 overheating experiments. You might also try running full-screen Flash video on the MacBooks/MacBook Pros. I ran 1080p full-screen Flash video on the highest-end 17" model, and it became extremely hot, while my W700 is cool to the touch playing exactly the same videos, plus the colors are more accurate and vivid on the W700.

Good luck!
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Re: W510 Screen flickers when showing grey gradient

#8 Post by craigmontHunter » Sat Nov 20, 2010 8:23 am

I remember that almost every laptop I have ever had had the flickering issue, especially on the greyed screen on windows2000 behind the logout bo. I have not tried windows 2000 on my t61, but that flickers on screen 4b. The i7 macbook pros have a severe overheating issue - one review found that the processor throtteled, and it still hit 105 deg C. They got it to run longer by putting it on it's side.
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