Great questions. I'm an expert in displays, and I totally understand why this happens.
However, the assumptions that many people make about pixel response is WRONG about glasses.
There are two assumptions that I need to educate, in order to explain better:
A) Pixel response time is not necessarily chief cause of crosstalk
A. Pixel response time (GtG) is not the same thing as pixel persistence (MPRT).
1. See Why Does Some OLEDs have Motion Blur?
2. See Blur Busters Law And The Amazing Journey To Future 1000Hz Displays
B) Not all pixels are refreshed at the same time
C) NVIDIA 3D Vision uses a strobe backlight
Please see this high speed video. A screen (even OLED) is refreshed sequentially from top-to-bottom. Pixel response is only for one pixel, but that doesn't mean the whole screen's of pixels are refreshed simultaneously.
From High speed video of LightBoost
The LightBoost mode (normally for 3D Vision) actually helped Blur Busters become popular, because this mode eliminated display motion blur. Such a display mode, perfect for 3D Vision, was also perfect for eliminating LCD motion blur. Even LightBoost has much lower MPRT response than the world's fastest OLED.
GtG response is not MPRT response
GtG response is not MPRT response
GtG response is not MPRT response
GtG is pixel transition time (pixel changes from one value to another in a finite amount of time)
MPRT is pixel visibility time (pixel stays a fixed visible color for a finite amount of time)
From: Blur Busters Law And The Amazing Journey To Future 1000Hz Monitors
For good 3D shutter glasses operation, it becomes more complicated than this, because of the screen scanout effect
(which you see in the above video too).
The LCD in a shutter glasses has a "response time"
(often slower than display!!)
Shutter glasses uses LCD -- the same technology in a common monitor.
There are only two pixels in shutter glasses: One massive lens-sized pixel for your left eye, and one massive lens-sized pixel for your right eye.
The big problem is that the shutter glasses have a finite response time itself (shutter fading between opaque-vs-transparent or transparent-vs-opaque in a finite time period), so the display actually has to behave unorthodoxly to make them work. LCD shutters are like one massive lens-sized LCD pixel.
But how the hell do I fix that?
Black frame insertion. Strobe backlight.
The main workaround for fixing shutter glasses crosstalk for the screen scanout problem is to use a form of black frame insertion to black out the screen BEFORE the glasses changes shutters (remember: LCD shutters "fade from opaque to transparent" over milliseconds.... so it's better for the screen to be blacked out during this moment!!!).
Black frame insertion can reduce persistence. Black frame insertion is used to black out the screen while the shutter glasses switch eyes. It can take a few milliseconds for a shutterglasses shutter to fade from "on-to-off" or "off-to-on". During this time period, The screen must be COMPLETELY BLACK
in order to AVOID CROSSTALK
. When a shutter glasses is switching eyes, one shutter is fading to black and the other shutter is fading to transparent (over milliseconds). That means both eyes can be semi-transparent. So even the world's fastest instant-pixel-response displays, WILL have very bad crosstalk.
Such screens that do this (aka NVIDIA LightBoost) naturally ends up having very low MPRT because a specific pixel is visible for a short time period. For years, Blur Busters had a LightBoost HOWTO
and a LightBoost FAQ
, how to commandeer and trick a 3D Shutter Glasses Mode into a Motion Blur Reduction Mode, as it was hugely much more profitable to sell this feature as a motion blur reduction feature. And now there are lots of LightBoost copycats
but they're targetted for motion blur reduction, not for 3D shutter glasses.....
Shutter Glasses Fighting Against Display
Shutter glasses in one refresh cycle, this simultaneously occurs:
1. Left eye "LCD-shutter" gradually fades to black (or vice versa); and
2. Right eye "LCD-shutter" graduallt fades to clear (or vice versa)
1. Top to bottom refresh over one refresh cycle
2. For each pixel, there's pixel response too (creates fade wipe effect in high speed video)
That's your attempt to hack most displays (LCD, OLED) display for 3D glasses
Shutter Glasses Working With Display
Shutter glasses in one refresh cycle:
1. Left eye "LCD-shutter" fades to black slowly (or vice versa)
2. Right eye "LCD-shutter" fades to clear slowly (or vice versa)
1. Refreshes in total darkness (80-90%) of refresh cycle
2. Display brightly flashes fully refreshed frame at the perfect moment for the shutter glasses
(when closed shutter is at its most opaque, and when open shutter LCD is at its most clear.
That's what NVIDIA LightBoost is. But you can reverse-commandeer a blur-reduction backlight into a 3D glasses mode!
Reverse Hack? Yes, That's The Good News
Hacking a 3D glasses mode for use as 2D motion blur reduction
In the past, we commandeered a 3D Shutter Glasses Mode into a Blur Reducing Mode. That's what Blur Busters did. We're the website that popularized the "LightBoost Hack" for this use, and #1 when you google "LightBoost".
Reverse Hack is possible!!! Hacking a 2D motion blur reduction mode into becoming a 3D glasses mode
However, the vice-versa CAN
be done with certain exceptions:
A. Look for a display that advertises motion blur reduction
B. Make sure 120 Hz is supported with that mode.
Overdrive artifacts causes a crosstalk problem. There's a way to massively reduce this. To reduce cross talk (caused by overdrive) further, make your colors slightly duller (about 10-20%) -- reduce dynamic range slightly (LightBoost-style poor colors) by raising digital black level and reducing digital white level (via NVIDIA Control Panel or AMD Catalyst Control Center) or configuring the computer to use only HDMI range (16 to 235). LCD panel overdrive is problematic at the fullblacks and fullwhites so artifacting occurs with those. http://www.testufo.com/crosstalk
is a very good test pattern for 2D blur reduction but is also 100% applicable to quality you can achieve with a mode. This extra digital headroom (not backlight brightness) below black and above white, reduces the overdrive artifact problem that creates amplified crosstalk.
These modes work adequately with 3D glasses
A. NVIDIA ULMB (in monitors that don't have 3D Vision)
B. BENQ Blur Reduction on 1080p monitors with the Large Vertical Total trick
C. Samsung Blur Reduction
D. ASUS ELMB
Remember, however, to use the dynamic range reduction trick (make your blacks digitally brighter, and makes your whites digitally darker) to fix the overdrive ghosting that occurs with those end-range colors. Doing that reduces ~80% of the crosstalk visibility in the reverse hack (commandering a blur reduction mode into a 3D glasses mode). This is exactly a major reason why LightBoost had crappy color, it was pre-compressed dynamic range. But you can intentionally do it with most blur reducing modes to reduce crosstalk.
Remember, TN LCD screens are always best. Also, global-flash strobe backlights are better for 3D glasses than sequential scanning backlights (which attempt to compensate for the screen scanout effect by flashing fully refreshed rows away from the still-refreshing areas of the screen).
Pixel transition time is unimportant if the pixel transition time occurs in total darkness -- that's how LightBoost works and it's possible to have MPRT lower than GtG. (This is how Blur Busters got started... LOL) For 120Hz, a backlight is flashed for only 1ms to 2ms which means the screen is completely dark almost 90% of the time, with a photographic-flash-quickness of a screen flashing at the very moment that the shutter glasses is in its best situation (most opaqueness of the shuttered eye, and most clearness of the non-shuttered eye) because the shutter glasses eyes fade back and fourth in a sinewavey way (point a 1000fps camera through shutterglasses pointing at a bright lightbulb -- and you'll see what I mean), so making screen visibility brief only at the most optmium moment of the shutter glasses -- minimizes crosstalk. Thanks to this, this gives an LCD screen plenty of time to finish GtG pixel transition in total darkness -- completely unseen by eyes -- (1ms TN screens especially -- given LightBoost gives 6ms- 7ms of total darkness between screen flashes) -- that really lowers crosstalk.
For good "3D Shutter Glasses Hack Displays", make sure that the display supports 120Hz strobed (black frame insertion). Some displays that have a Motion Blur Reduction Backlight
will make acceptably decent 3D shutter glasses displays.
You can shop for monitors with blur reduction. TN will generally have less crosstalk, IPS a bit more crosstalk, and VA even more crosstalk. Study the Large Vertical Total tricks, those crosstalk-reduction tricks also helps 3D glasses too. And obviously, the little-known dynamic-range-reduction trick (yes, colors will be 10% - 20% duller, but 80% of the crosstalkv can disappear).
What Screen Tech Works Best?
Currently, it is in this following order:
1. Strobed TN LCD
2. Strobed IPS LCD
3. Strobed VA LCD
(NOTE: Strobed VA LCD is ghosty/crosstalky; only Samsung seems to produce OK quality -- make sure it's warmed up hot (warm VA has less crosstlak) and make sure to really raise the digital black levels quite a bit to help-out the overdrive overshoot-compensation range below your raised digital black)
Strobed OLED will be even better but they don't exist in simultaneous "120Hz-and-BFI" yet. You need a true 120Hz mode that also simultaneously has black frame insertion.
Also, if your/their 3D glasses site wants me to write a guest article -- I'd be happy to write one. Please contact me at mark[at]blurbusters.com ... I do work with monitor manufacturers from time to time, and have an scientific understanding of the limitations of shutter glasses too, and how to coax displays to work better with them.
...And please support Blur Busters by shopping monitors in the monitor lists below.