Motion blur illustrated - Page 2 - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #31 of 52 Old 10-09-2008, 12:13 PM
AVS Club Gold
 
Mark Petersen's Avatar
 
Join Date: Dec 2000
Posts: 4,671
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by xrox View Post

PDP phosphors are even worse.

Also very interesting. Each color doesn't even share the same peak luminance. Presumably it relies on the PWM "on state" time to provide the right amount of perceived luminance but you would think that it would be designed such that PWM would adjust only the greyscale, but with the same peak luminance for each color. But apparently not.

It's amazing that these various display technologies yield similar looking images and we don't see much more artifacts than we do.
Mark Petersen is offline  
Sponsored Links
Advertisement
 
post #32 of 52 Old 10-09-2008, 01:47 PM - Thread Starter
Senior Member
 
THE_COW_IS_OK's Avatar
 
Join Date: Apr 2002
Location: France
Posts: 436
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by xrox View Post

Solutions: Using the analogy above, if you turned off the laser while your retina is in motion then you completely eliminate the line. The true essence of all hold type blur reducing methods is to reduce the hold time. A blanking period is only one method. Another is to combine increased refresh rates with interpolated frames. Even better is to use both methods. If you look at hold times for individual display systems you can see a correlation to blur performance reputation.

Totally agree, and since frame interpolation is not perfect science (real motion is unpredictable and certainly not linear...) and since you will certainly drift away from film director intent, blanking period between frames seems the best solution.

Quote:
Originally Posted by xrox View Post

Hold times for various displays (note: this is not response times!!!!)

PMOLED - microseconds
CRT - 2ms
LCD(120Hz + interpolation + backlight scanning) - 4ms
Plasma - 4-6ms
LCD(120Hz + interpolation) - 8.3ms
AMOLED - 16.7ms
LCD(60Hz) - 16.7ms

Very Informative. A lot these tech holds great promise for the future but are not available for the consumer, let alone in a FP... I would love to see data for single chip and 3 chip DLP. I suspect a 3 Chip DLPs will perform better in this area then regular plasma since there are no phosphore decay issues. I also suspect single chip DLP to perform worse then plasma & 3 chip DLPs since each primary is burst regularly (12 times in my 7 segment 6x 11s2 color wheel) during the whole frame period and blanking time between 2 successive frames is severly reduced.
THE_COW_IS_OK is offline  
post #33 of 52 Old 10-09-2008, 02:44 PM - Thread Starter
Senior Member
 
THE_COW_IS_OK's Avatar
 
Join Date: Apr 2002
Location: France
Posts: 436
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Ohlson View Post

THE_COW.
What do you mean LCD can not do 120fps, the latest flat panel lcds and the new htps panels from Epson do 120Hz. Showing an interpolated frame must be equivalent to showing a repeat of the original frame.
60p input ->60 frames + 60 interpolated frames

Current LCD response time can hardly keep up with 60Hz . My LCD is advertised as 6ms response time so 60fps 16.6ms frame time should not be a problem. Yet still, In my LCD shot with 1/320 shutter, you can still see trail of the letters belonging to the previous frame! How you expect it to coop with 120Hz then... I am just extrapolating from results I got with 60Hz. Nothing fancy.
Even if the electronics are fast enought to produce 60 interpolated frames and send commands for the drive to change state of the pixel 120 times per second. We are not garanteed the panel will deliver. So pls understand my skepticism over current 120Hz LCD panel performance...

Quote:
Originally Posted by Ohlson View Post

The drive of d-ila as I imagine it working.
The level is set by short time controlled high voltage pulses. Thus a short pulse should be able to set a level close to the previous one and do that quickly.

I expect better results trying 120Hz on LCOS then LCD.

Quote:
Originally Posted by Ohlson View Post

How long do black inserted frames have to be to lower hold blur? With quick black frames we will not lose so much brightness or contrast.

Apparently the answer is subjective and every person will have different threshold. Retina/brain/conditioning all play a role. I have yet to see a study that address the specifity of the issue.
THE_COW_IS_OK is offline  
post #34 of 52 Old 10-09-2008, 06:46 PM
Advanced Member
 
peteer01's Avatar
 
Join Date: Mar 2007
Location: Tokyo
Posts: 742
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by THE_COW_IS_OK View Post

Current LCD response time can hardly keep up with 60Hz . My LCD is advertised as 6ms response time so 60fps 16.6ms frame time should not be a problem. Yet still, In my LCD shot with 1/320 shutter, you can still see trail of the letters belonging to the previous frame! How you expect it to coop with 120Hz then... I am just extrapolating from results I got with 60Hz. Nothing fancy.
Even if the electronics are fast enought to produce 60 interpolated frames and send commands for the drive to change state of the pixel 120 times per second. We are not garanteed the panel will deliver. So pls understand my skepticism over current 120Hz LCD panel performance...

Taking a photo of an LCD or any other monitor is hardly an exact science. I've taken close to 100 photos of LCD projectors and my computer's LCD screen to test the image lag of various projectors, and it's possible to end up with a 1/120th of a second photo that is one frame crystal clear, and a 1/500th of a second photo that shows two different frames equally, giving the impression of strong blur. Don't assume that a 1/320th image is how every 1/320th of a second appears.

Enjoying my second TW4000 and my new screen.
As my wife said, "Wow, it really does look a lot better...and if I think that way, imagine how you must think it looks!"
peteer01 is offline  
post #35 of 52 Old 10-09-2008, 09:49 PM
Newbie
 
ericwillson's Avatar
 
Join Date: Oct 2008
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Thanx for the reviews.......................................
ericwillson is offline  
post #36 of 52 Old 10-09-2008, 10:50 PM
AVS Special Member
 
Ohlson's Avatar
 
Join Date: Oct 2001
Location: Falun, Sweden
Posts: 5,434
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
COW.....
I read your words as lcd meaning lcd flat panel.
Htps panels in 3LCD projectors is not the same technology as in lcd flat panel tvs. The cells you neeed to control are so much smaller on a display device that is physically only a couple of centimerters in diagonal.

Mattias Ohlson
Ohlson is offline  
post #37 of 52 Old 10-10-2008, 01:07 AM - Thread Starter
Senior Member
 
THE_COW_IS_OK's Avatar
 
Join Date: Apr 2002
Location: France
Posts: 436
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by peteer01 View Post

Taking a photo of an LCD or any other monitor is hardly an exact science. I've taken close to 100 photos of LCD projectors and my computer's LCD screen to test the image lag of various projectors, and it's possible to end up with a 1/120th of a second photo that is one frame crystal clear, and a 1/500th of a second photo that shows two different frames equally, giving the impression of strong blur. Don't assume that a 1/320th image is how every 1/320th of a second appears.

Bad timing is accounted for while taking the shot. Actually you can use this to your advantage in order to know more about your display .Here is an example:
Lets take the example of an LCD with switching time of 4ms running @60FPs (16ms per frame) and no blanking time. I ll assume switching starts at the begining of every frame. Frame 1 starts @time 0.

0->4ms (the pannel is switching from previous frame to frame 1)
4ms->16ms (Frame 1 is on)
16ms->20ms((the pannel is switching from frame 1 to frame 2)
20ms->32ms(Frame 2 is on)

Now if you shoot with a speed 1/320, the shutter will remain open for 3ms. If this time window occurs during the intervals(7->13ms, 23->29ms) you WON'T get any blurr and ((6+6)/32=37) thus 37% of your shot should contain no blur if manufacturer advertised spec are correct!

In the case of single ship DLP with negligible switching time (in micro seconds) and blanking time, the numbers comes out around 62.5%.

With very fast shutter speed and a lot of shots, it is very easy to reach conclusive results about panel response. I took 25 shots with my LCD and Guess how many clean shot(ie no blurr) I had with my LCD with a shutter speed of 1/320s????? NONE! and that was conclusive for me to know my LCD was short in response speed. With the 11s2 DLP @1/1000s I had 9/10 shots without any blur and 7/10 shot with a shutter of 1/320s. Hence I decided to post one with no blurr since the remaining 3/10 were due to shot bad timing(overlap with frame transition)


SAH measurments on the other hand, requires much more sophisticated tools and methods to get accurate results. My method was in no way intended to be an industry benchmark for accurately measuring SAH . Yet it was enough for me to illustrate what I see with my eyes and assess different display tech.
THE_COW_IS_OK is offline  
post #38 of 52 Old 10-10-2008, 01:52 AM - Thread Starter
Senior Member
 
THE_COW_IS_OK's Avatar
 
Join Date: Apr 2002
Location: France
Posts: 436
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Ohlson View Post

COW.....
I read your words as lcd meaning lcd flat panel.
Htps panels in 3LCD projectors is not the same technology as in lcd flat panel tvs. The cells you neeed to control are so much smaller on a display device that is physically only a couple of centimerters in diagonal.

Ah, tkx point taken. IF you have chance to try my test and post results. It will be nice to compare different LCD models.

As for me, my hopes for reaching blur free displays tends to be on the DLP side. A single chip DLP with LED light switching off for certain time between successive frame sounds like a nice and relatively cheap solution. You will suffer more dithering and brightness loss though .... a 3 Chip DLP with LED will get even better results, but how expensive is that
THE_COW_IS_OK is offline  
post #39 of 52 Old 10-10-2008, 02:47 AM - Thread Starter
Senior Member
 
THE_COW_IS_OK's Avatar
 
Join Date: Apr 2002
Location: France
Posts: 436
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Ohlson View Post

How long do black inserted frames have to be to lower hold blur? With quick black frames we will not lose so much brightness or contrast.

ON a second though , I have my little idea in order to determine how much blanking time is enough for blur free viewing. For that you need a HTPC, 3 Chip DLP, and a light meter. My method is really simple:

With a 3 Chip DLP, you not only have immediate switching time (in Micro Seconds) but you hold time is propotional to light intensity, and your blanking time is inversly propotional to that. Displaying a white(100IRE signal with 3 primary drive/contrast maxed out) text on black background will leave the mirrors on "ON" state for the whole duration of the frame and will cut blanking time between frames to zero. With the same "marquee" settings screen saver, put speed on max and instead of playing with the scrolling speed, try to play with the PJ Contrast Decrease contrast slowly (that should increase blanking time between frames and decrese hold time) until you are able to read the text clearly. With a light meter measure the intensite of light(I1) at this same contrast with a 100IRE field. Then max out the contrast again and measure the light intensity of the 100IRE field again(I2). At this stage, you can easily compute your hold time and blanking time:

HoldTime(ms) = (I1/I2) * (1/60)
BlankingTime(ms) = (1/60ms) - HoldTime.

Now you have your blanking time threshold for your own blur free viewing . From here, you can extrapolate how much black frames are enough for Blur free LCD viewing. That assuming of course you solved LCD slow switching time....

AH I wish I had a 3 Chip DLP and experiment with that......


PS: I was reading a DLP paper and noticed that on states doesn't have to be contiguous in time since they use ADS-Binary with bit-splitting techniques. In this case, blanking times will be spread across the time frame and the test is mute.
As long as brightness is trade off for better motion handling and brightness sells... am not too hopeful on the near future with current tech.
THE_COW_IS_OK is offline  
post #40 of 52 Old 10-10-2008, 12:41 PM
AVS Club Gold
 
Mark Petersen's Avatar
 
Join Date: Dec 2000
Posts: 4,671
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
One other thing that is relevant to this discussion about the blur caused by S&H. It's not always the case that adding black at the end of a pixel refresh will reduce the perception of motion blur. What needs to happen is all of the pixels representing the object in motion need to have black inserted at the same time.
As a case in point, I've posted this link before: http://www.techmind.org/lcd/ which describes common LCD inversion (refresh) schemes and also test patterns that examine those schemes. As can be seen many of these schemes don't refresh all of the pixels at the same time but instead refresh pixels based on some alternating schemes (every other row, every other column, etc.). If off (black) time was inserted during refresh using any of those schemes, I don't think it would help reduce the perception of motion blur at all.

I don't think that these types of refresh schemes are specific only to LCD panels, I think they are often used in PDP and other display types because they are very useful at reducing flicker to unnoticeable amounts.
Mark Petersen is offline  
post #41 of 52 Old 12-15-2008, 06:55 AM
AVS Special Member
 
conan48's Avatar
 
Join Date: Jun 2003
Location: Igloo
Posts: 2,159
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked: 155
Anyone run any motion test with the new JVC RS10 or RS20?
conan48 is offline  
post #42 of 52 Old 12-15-2008, 09:31 AM
AVS Addicted Member
 
stanger89's Avatar
 
Join Date: Nov 2002
Location: Marion, IA
Posts: 17,359
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 87 Post(s)
Liked: 129
You know, it would be interesting to see video of these technologies shot with one of those new cameras that shoots in high speed, like Casio's that can do 1200fps:
http://www.engadget.com/2008/01/06/c...n-superslowmo/

See what an anamorphoscopic lens can do, see movies the way they were meant to be seen
stanger89 is online now  
post #43 of 52 Old 02-07-2009, 02:19 AM
Senior Member
 
MacBuster's Avatar
 
Join Date: Dec 2003
Location: Calgary
Posts: 415
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I'm going to cough up this thread because I'm investigating the motion blur capabilities of the projectors I am considering.

My needs are more practical than academic. I watch a lot of football and hockey and see "streaky" balls and pucks on my LCD flat panel, but less so on my Plasma.

What of the current technologies most closely resembles "plasma" motion handling.

It certainly sounds like that would be DLP, with perhaps LCOS next, followed by LCD?
MacBuster is offline  
post #44 of 52 Old 02-07-2009, 03:19 AM - Thread Starter
Senior Member
 
THE_COW_IS_OK's Avatar
 
Join Date: Apr 2002
Location: France
Posts: 436
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Since DLP is a Pulse Width Modulation tech like Plasma, this is the tech you should consider first. But since both tech implement PWM differently, I encourage you to demo DLP before committing.

By the way, due to the much smaller die size, LCD in FP handles motion much better then in Direct View displays. This is was confirmed when I run FPD moving scope patterns on many FP/Direct View LCD displays. Hence, I would not disregard LCOS/LCD FP automatically.
THE_COW_IS_OK is offline  
post #45 of 52 Old 02-07-2009, 07:11 PM
Senior Member
 
lightguy's Avatar
 
Join Date: Jan 2009
Location: Dallas/Ft Worth
Posts: 372
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by conan48 View Post

Anyone run any motion test with the new JVC RS10 or RS20?

I'm wondering as well.
Does the RS series run at 120HZ ?
lightguy is offline  
post #46 of 52 Old 02-07-2009, 07:49 PM
AVS Special Member
 
WOLVERNOLE's Avatar
 
Join Date: Jun 2001
Location: DUMFRIES, VA USA
Posts: 2,544
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 12
Quote:
Originally Posted by lightguy View Post

I'm wondering as well.
Does the RS series run at 120HZ ?

I thought that it had been posted numerous times, including in this very thread, as @96 Hz. Someone feel free to correct me.
WOLVERNOLE is offline  
post #47 of 52 Old 02-07-2009, 07:57 PM
Senior Member
 
MacBuster's Avatar
 
Join Date: Dec 2003
Location: Calgary
Posts: 415
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by THE_COW_IS_OK View Post

Since DLP is a Pulse Width Modulation tech like Plasma, this is the tech you should consider first. But since both tech implement PWM differently, I encourage you to demo DLP before committing.

By the way, due to the much smaller die size, LCD in FP handles motion much better then in Direct View displays. This is was confirmed when I run FPD moving scope patterns on many FP/Direct View LCD displays. Hence, I would not disregard LCOS/LCD FP automatically.

This is interesting and something I hadn't considered. In fact, my AX-100 (which departed some time ago, RIP), seemed to handle things much better than my current 120hz Toshiba Regza.

My cheap Insignia 1080p plasma is light years ahead of the Tosh.

I do see rainbows, so despite not having seen current generation DLP, I am a little nervous about a DLP investment.
MacBuster is offline  
post #48 of 52 Old 02-07-2009, 10:00 PM
Advanced Member
 
mike infinity's Avatar
 
Join Date: Oct 2007
Posts: 699
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Just to add:

I did extensive testing on this when I bought and returned my sony xbr4 lcd flat panel. One thing I did notice was the the display induced blur was temperature dependent to some degree. The warmer the panel, the less the motion blur. I never noticed any blur, for example, on my hitachi 50v500 RPTV. In retrospect I guessed that the lamp heat significantly improved refresh time...which, if true, would carry over to front projectors.

I also noticed the blur/smearing depended on the transition colours. Dark objects moving across dark backgrounds were just awful on that set. Never mind that my 4 year old LCD pc monitor might have had inferior blacks, but it didn't have any significant blur.

For the record, I tried the same tests on my Benq W5000 this past week, it passed with flying colours...no blur on my torture test videos. From what I've seen, DLP wins this contest next to CRT PJs.
mike infinity is offline  
post #49 of 52 Old 02-07-2009, 10:29 PM
Senior Member
 
lightguy's Avatar
 
Join Date: Jan 2009
Location: Dallas/Ft Worth
Posts: 372
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by WOLVERNOLE View Post

I thought that it had been posted numerous times, including in this very thread, as @96 Hz. Someone feel free to correct me.

It was said the RS1 runs at 96 back in October;

Quote:
Originally Posted by Ohlson View Post

Mark P.
1 Good to hear JVC is working at the 120Hz level. It is kind of surprising they do movies at 96Hz when 120Hz is possible.


Then more mention was made of 120Hz;

Quote:
Originally Posted by THE_COW_IS_OK View Post



I expect better results trying 120Hz on LCOS then LCD.


So I was was thinking possibly the new RS10/20/350/750 may have been bumped to 120Hz.

One more question; Why so F'N rude ?
Feel free to correct me.
lightguy is offline  
post #50 of 52 Old 02-08-2009, 04:34 AM
Advanced Member
 
mike infinity's Avatar
 
Join Date: Oct 2007
Posts: 699
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
As far as I know, frame interpolation helps with SAH artifacting like judder. Higher refresh rates won't fix smearing unless the pixels can keep up...but if they could keep up you wouldn't need higher refresh rates in the first place (except to avoid 3:2 pulldown...not to fix smearing/blur).

Frankly, the 120Hz mode on the sony XBR4 IMO was utterly useless and FI would never be part of the equation for me purchasing a PJ.
mike infinity is offline  
post #51 of 52 Old 07-19-2012, 07:26 PM
Advanced Member
 
sarangiman's Avatar
 
Join Date: Feb 2006
Posts: 542
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 20
Quote:
One thing I did notice was the the display induced blur was temperature dependent to some degree. The warmer the panel, the less the motion blur.

Yes! This also explains why I noticed motion blur immediately on my folks' Samsung LCD flat panel TV, but hadn't noticed it much on my Panasonic PT-AE900U 720p projector (which was considerably older than the Samsung TV as well)!
Quote:
With very fast shutter speed and a lot of shots, it is very easy to reach conclusive results about panel response.

Exactly! Which is why I shot 24fps video at 1/800 shutter speed to compare response time of a BenQ W7000, Epson 8350 (60Hz), Epson 3010 (480Hz panels). I believe it's actually important to shoot at 24fps just so that at some point you're guaranteed to be 'out-of-phase' with the 60Hz refresh rate of my video signal going to the projector (from my HTPC). Basically, at some point, you want to 'sample' the "16ms->20ms((the pannel is switching from frame 1 to frame 2)" window that THE_COW_IS_OK mentioned.

Unsurprisingly, the BenQ W7000 DLP performed amazingly.

The Epson 8350 performed slightly worse than the 3010, but not significantly slow. Which is surprising; I would've though that the panels in the 3010 would have faster response times given the claimed 480Hz processing... but as was mentioned earlier, just because you might have faster processing for frame interpolation or what have you doesn't mean the LCD response times will be good enough to keep up. That's up to the manufacturer & selection of panels!

Great thread!
sarangiman is offline  
post #52 of 52 Old 07-24-2012, 06:42 PM
AVS Club Gold
 
AV Science Sales 3's Avatar
 
Join Date: Jul 2011
Posts: 259
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by THE_COW_IS_OK View Post

Motion blur illustrated.


Recently on the forum, the issue of motion blur is stirring a lot of attention by folks like me for example who are very sensitive to this. Since my old CRT FP died on me early this year, I bought and sold 3 different PJs (Sanyo LCD/JVC RS2/Marants 11S2) and I have yet to find a display tech that handles motion as well as my old PJ. Some people are still skeptical and believe the topic of motion blur is mute. Hence I decided to take hold of my SLR camera and devised a little test to proof that motion blur DO exist and is more or less apparent depending on the display technology being used. Before I tackle the issue of motion resolution, it is important to differentiate between 2 major factors responsible for this blur: Slow Response and SAH(Sample and Hold) effect.

Slow Response is usually caused by pixel not being fast enough to change state for every frame. LCD/LCOS are especially vulnerable to this problem. You can notice it with fast camera pans, fast action sports, and it is especially obvious when group of pixels of close tonal range are moving around the screen. Motion blur will introduce softness to the image and can hide subtle tonal changes in people skins and textures.

In theory, it shouldn’t show with PWM (Pulse width modulation) display since they change pixel state(on/off) almost instantaneously(in micro seconds). For instance, DLP is totally immune to this type of blur (as we will see in the next images). Plasma might leave some phosphor trails and hence some models tend to exhibit this flaw to certain extent.

SAH (Sample and Hold) effect is due to how the eye-brain interprets the image perceived. Since light falling in the eye retina is persistent and the brain integrates light intensity over a short period of time, a certain amount of blanking time is required between frames for the brain to easily differentiate sequential images and interpret movements. Not doing so, the brain will integrate and join 2 subsequent frames and this will be perceived as fuzziness in the image. LCD/LCOS blanking time is almost nil since pixel state is always on for the duration of the whole frame. Single chip DLPs have some blanking time but definitely not as long as 3 Chip DLP due to its color wheel that turns several round per frame and display each color twice per round. 3 Chip DLP blanking time is directly proportional to pixel brightness intensity, and knowing the average pixel IRE hover in the 30s, add gamma to the equation and we’ll get on average very long blanking times with off state mirror time. CRTs have relatively long blanking times as well (about 14ms with 60fps material assuming 2ms phosphor decay time)


The Test:


My test is easy to reproduce by anyone who is feeding his PJ with an HTPC running Windows OS and is curious to assess his display and his motion sensitivity. There is a XP screen saver named “marquee” that scroll a text horizontally. I went to “marquee” settings and filled the text box with “ININI”. I then started playing with scrolling speed trying to determine the text legibility speed threshold above which I couldn’t read the letters anymore. I performed this test with LCD/Single Chip DLP/LCOS/CRT and took screen shots with my camera at different shutter speed. For reference, I decided to attach 2 screen shots for each display tech I tested. One taken with a 1/340s shutter speed that test pixel response ability to redraw the text at different location for every frame. I added another with 1/60s shutter speed that mimic what my eyes perceive (I tried about 20 different shutter speeds from 1/20s ->1/500s and found image produced by 1/60s best reproduce what MY eyes actually sees).

Great summary. I would also like to add (since I get this a lot), having 120/240hz processing does not necessarily fix this. Often the issue lies at the panels (as you have stated essentially). You can send the fastest possible signal to the panels, but if they are the bottleneck, they are the bottleneck. Not saying it will not help for certain situation and such, but again it is sort of a bandaid on the underlying issue.

Jason C. Turk
Technical Support, Customer Service, Sales and Installations
A/V Science, Inc.
Direct Line: 585-645-1004
Email: jason@avscience.com

Don't forget my nearly 13,000 posts under my old ID!

AV Science Sales 3 is offline  
Reply Digital Hi-End Projectors - $3,000+ USD MSRP

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off