Originally Posted by kevinsbane
Ghosting is caused by slow pixel transition times - the pixels cannot transition fast enough to the correct colour, and thus you see a ghost image as the pixel is half-transformed.
Today, it is more like 90% transformed, 98% transformed, 99% transformed.
Depends on monitor and situation, but generally, LightBoost ghosts are less than 1% intensity.
Originally Posted by Aesthethc
The response time for this monitor is 2ms.
LightBoost motion blur (~1.4ms) is actually less than the pixel transition time as pixel transition time is executed while the monitor is in total darkness (between strobe flashes of backlight). It's bypassing the pixel transition speed limitation. With LightBoost strobing, every refresh at 120Hz is illuminated only for 1.4 milliseconds, and kept in total darkness for 6.9 milliseconds between refreshes. (Confirmed by multiple sources; both Blur Busters and TFTCentral oscilloscope tests). The 2ms transitions fit nearly completely within the 6.9ms of darkness (unseen by human eye), but not 100% completely as occasionaly a small amount of transition (usually less than 1%) is still visible -- which then manifests itself as the very, very, very, very faint LightBoost ghost effect. So the vast majority of your motion blur has already "broken the LCD pixel transition speed barrier", thanks to LightBoost.
For info on LightBoost ghosting, see below.
Originally Posted by inedenimadam
Its not the only possibility, but ghosting can certainly be caused by poor cable shielding, and it is the first place to start because moving some cable's around and unplugging printers and such is a 0 cost fix
Common advice, but belay this, see below. Cable ghosting only happens on analog, and LightBoost doesn't operate on analog, and the original poster is using LightBoost. The OP is describing known LightBoost ghosting that only happens on fast-moving high-contrast objects (e.g. jets in a blue sky)
Originally Posted by Aesthethc
Is it really a cable issue?
Not a cable issue.
Coincidentially, there is a new Blur Busters article about ghosting/overdrive: LCD Motion Artifacts: Overdrive
That said, the OP is talking about LightBoost specific ghosting, which exists albiet much fainter than non-LightBoost ghosting.
They show up as this:
(From the new article at www.blurbusters.com/faq/lcd-overdrive-artifacts/
Originally Posted by Blur Busters
Without overdrive, LCD displays are prone to ghosting. Ghosting is typically caused by the asymmetric speeds of pixel transitions. LCD pixels often transition faster to a specific value, than back from a specific value. This creates the differences in motion artifacts on the leading edge versus the trailing edge of moving on-screen objects.
Observe the red rectangle above. That's what it looks like; LightBoost faint razor-sharp-ghost similar in intensity to 3D crosstalk. (3D crosstalk is a form of ghosting too!)
Ideally, LightBoost ghosting is much, much, much fainter than non-LightBoost ghosting, if properly set up.
LightBoost ghosting is different than non-LightBoost ghosting, is that it simply looks like a sharp faint double-image effect, that shows up along the direction of motion. Instead of a blurry ghost, you've got a ultra-sharp ghost double image, which is simply the remnant state of the LCD screen at the moment of the next backlight strobe. (See high speed video of LightBoost
for how LightBoost works; it strobes the backlight on fully refreshed frames). Sometimes the pixels are only 99% transitioned by the time the next time the backlight needs to flash. This shows up as the faint razor sharp ghost.
That can manifest itself as a very faint trailing double-image, similiar to what is seen on the left edge of the tower at the TestUFO Eiffel Tower Test
.... This is generally unavoidable but the ghost is nearly non existent on VG248QE / XL2411T / XL2420TE / XL2420Trev2.0 while it is more visible on VG278HE / XL2420T(orig rev 1.0) and somewhat visible on VG278H and XL2720T's. That said, the VG278H (non-E) can eliminate its LightBoost ghost by lowering your monitor's onscreen contrast down to about 50. However, the colors do not look nearly as good so I do not recommend so. If you hate the LightBoost ghost, but want good colors, a good compromise setting is an ASUS monitor on-screen Contrast ratio of about 70. Personally, I prefer 90 (VG278H specific) since I like brighter colors, even if I gain a small amount of LightBoost double-ghost. Certain monitors (VG248QE) don't go above about 50 Contrast ratio without clipping whites, so make sure to be mindful of your calibration when attempting to diminish the ghost.
LightBoost ghosting is generally more visible at the bottom edge of the screen, and sometimes the top edge of the screen. This is due to the freshness of the strobes relative to the timing of pixel transitions. This is apparent in the high speed video of LightBoost, linked above.
When does LightBoost ghosting happen? Only if these two are met:
1. Fast motion; AND
2. High contrast (the same type of material where 3D crosstalk normally occurs)
(use Chrome or another 120Hz friendly browser)
Solutions to LightBoost faint sharp ghost effect:
- It's normal and very faint (much fainter than non-LightBoost ghosting), only shows up on sharp high-contrast boundaries along motion. It's unavoidable just like occasional 3D crosstalk is unavoidable. Just ignore it.
- If you prefer, adjust contrast downwards in your monitor OSD menu. This will cause the LightBoost ghost to fade.
- If it's a major annoyance; get one of the "1ms 144Hz" panels, as they have darn near zero LightBoost faint-ghosting. But they have less contrast ratio than the 27" 120Hz panels which typically has better LightBoost color. There is generally a tradeoff between contrast ratio and ghosting, and there's a scientific reason (overdrive headroom -- lower contrast gives more headroom for overdrive). Done properly, strobing can help hides the vast majority of ugly ghosting/overdrive, but not completely. VG278H's have much better LightBoost color, so I'd suggest tolerating the faint ghost effect found on VG278H's
Hope this helps!Edited by mdrejhon - 9/30/13 at 12:16pm