Why does this image cause screen flickering?

Image from Avast! software overlay on desktop:

Image from SteamCommunity website (most pronounced around the second horizontal gray divider):

I realize that this is an issue with my hardware, these images just demonstrate the sorts of patterns and colors that cause the problem for me.

I'm using an LG FLATRON E2350V LCD monitor (LED backlight) at 1920x1080 at work and certain patterns like the above linked image cause the region displaying said image to flicker. There is also extreme tearing when moving that image around the screen.

I'm wondering if this is an artifact of the LED backlighting, and if there's anything I can do about it. There is no software option to change the refresh rate from 60 Hz, but I can adjust the clock and phase through the hardware menu (currently at defaults of 50 and 74, respectively). If I bump the clock up to 51 or down to 49, the flickering goes away but the tearing is still excessively noticeable, and other elements on the screen look blurry (this cycles in and out of focus the farther one goes).

At home I use a different make/model LED backlit LCD (same size/res) and have the flickering problem with the second example image.

Is there a general method to fix this issue, or do I simply have to play around with the clock until everything looks solid and stable, per monitor?

wes

Posted 2011-04-21T17:01:54.530

Reputation: 645

on my laptop the image flickers when scrolling but not when it is not moving. internal display is connected with lvds – Suici Doga – 2017-07-14T12:11:38.950

1@Sathya, I intentionally did not embed the images because when they are resized to fit the post restrictions the pattern I intended to show is warped. – wes – 2011-04-25T16:52:14.727

you can always rollback the changes. Also, I had linked the images as well. – Sathyajith Bhat – 2011-04-25T17:21:54.623

Answers

If your monitor is still using good ol' VGA cable and not HDMI or DVI, you might try changing the cable type to one of the digital ones (HDMI, DVI,...).

Your problem smells like an analogue issue, that the high frequency of the one-pixel color changes does not get trough undisturbed, or that the monitor is not perfectly synchronized.

Turbo J

Posted 2011-04-21T17:01:54.530

Reputation: 1 919

I suspect you could be right, but I go through a VGA KVM switch. Would a digital cable with a VGA converter be any better or exactly the same? – wes – 2011-04-25T17:38:56.930

No, a digital cable with VGA converter most likely generates MORE problems. The KVM switch itself is actually a likely candidate as a source of the problem. Is this a "simple switch" type or an electronic KVM? – Turbo J – 2011-04-25T21:07:38.190

I believe it's a simple switch type, powered through USB. – wes – 2011-04-25T22:15:58.767

This can be one of two things. (Both effects might even contribute to the problem at the same time.)

An analog timing problem, if the signal goes through a VGA link.
A so called inversion effect which is inherent in how LCD panels are driven, which makes certain types of pattern behave badly on different models of LCD panels.

Here's a page which both explains these problems in detail, and offers test images to figure out which problem is happening for you.

http://www.techmind.org/lcd/

As Turbo J suggests, you should definitely try to use a digital link all the way, if at all possible,

nitro2k01

Posted 2011-04-21T17:01:54.530

Reputation: 2 259