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View Full Version : So how good is Nvidia's LCD overdrive?


shockwave203
07-31-05, 12:17 PM
I read that Nvidia released an LCD overdrive option which is supposed to decrease the response time of pixels by supplying them with more voltage.

NVIDIA has added:

* LCD panel overdrive, to alleviate panel ghosting artifacts with fast moving video on notebooks displays

http://www.advancedimagingpro.com/article/article.jsp?siteSection=66&id=624

Supposedly this works with the Go6800? Has anyone seen improvements in response times?

jAkUp
07-31-05, 01:50 PM
Nice! I never heard of it! Interesting idea...

Roadhog
07-31-05, 01:56 PM
doesnt sound good :O

thanosAIAS
07-31-05, 01:57 PM
I'm scared :O

shockwave203
07-31-05, 02:20 PM
I think they're aiming at bringing it to the desktop market. Phillips has some nice info on the feature:

LCD Overdrive

Another well-known problem even with active-matrix LCDs is the poor response time of their LCD pixels, which can amount to several tens of milliseconds. This is made worse by the fact that small changes in grey-scale actually take longer than black-to-white or white-to-black transitions. The result is a smearing of picture motion, because the pixels cannot keep up with the changing grey-scales caused by moving objects in the image.

To overcome this problem, Philips Research has developed a technique for momentarily 'over-driving' each pixel with a voltage higher than is needed to achieve the required static grey-scale change. Establishing the correct amount of overdrive requires measurement of the response times for all possible grey-scale transitions, but this only needs to be done once for a particular type of LCD and is then built into pixel processing algorithms in the display driver electronics.

http://www.research.philips.com/newscenter/archive/2004/videoprocessing.html

Clockwork
07-31-05, 03:09 PM
I'm a bit confused as to how they can do this via software.

I have a Samsung 193p+ (which uses "Magicspeed", Samsung's version of overdrive). The Viewsonic VP191 and the VX924 use overdrive as well, but I thought this was strictly a hardware based feature.

How is nVidia achieving this via drivers?

Lemur.fi
07-31-05, 03:41 PM
Couldn't find better oscillator pics but atleast these give some sort of an idea what it is about:
http://graphics.tomshardware.com/display/20050526/viewsonic-07.html

It is nothing new. No one just saw the need to bring it to the LCD world before. I guess they couldn't make the transistors any faster. Then again, it is more likely that they just wan't to use the cheap old parts and still claim it is something new and spectacular. :rolleyes:

PS. Clockwork, remember that notebook displays are a bit different from the "real" LCD monitors.

subbo
07-31-05, 06:54 PM
I've seen this overdrive tech in the Fujitsu-Siemens C19-4 that has an MVA-Overdrive panel and I can say its peformance is by far the best I've seen yet on an LCD.

I recently set up a "4ms" X912 Viewsonic panel for a friend and its performance was nowhere near the C19-4 in both colors (either burnt through or too dark) and response time (lots of trails in white-black contrasts in games), also the viewing angle (ie desktop blue color vertical flatness) was superior on the C19-4 whilst the Viewsonic had clear fading towards the top.

The only problem with the C19-4 is the lack of DVI, but when somebody comes out with a 20" or larger MVA-O panel with DVI, I'll go for one. My current 20" uses an older MVA panel and has superior color and angle performance to most displays but the response could be better (especially with opposite-color prediction artifacts, a system that tries to wake up the pixels faster by flashing the opposite color before drawing the actual color).