What can the human eye detect (response time)

h41cyon

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With the response times on LCDs becoming lower and lower nowdays the question comes up: "Where is the threshold of the human eye/brain with respect to detecting the response time of a pixel changing from one color to another, black to white or anywhere inbetween.

I've heard that the response time on CRTs are usually less then 1ms, and that seems to be fast enough so that the human eye percieves an instant change. So then at what delay can we actually detect a transition?
 

Nytegard

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It varies person to person honestly.

Take a few of the messages here on Hardforums about LCDs.

Quick Sumarry:

P1 - "Hey, can I get a review of xxx LCD?"

P2 - "Yeah, xxx LCD is horrible! Go with CRT's. They don't ghost."

P3 - "What are you talking about? xxx doesn't ghost!"

P2 - "Dude, what are you smoking? xxx has terrible ghosting"


What's acceptable to one person is not to another. Generally, 30 fps is considered what is needed to make smooth animation for the human eye. But there have been studies where people were able to detect single images and what they were in a 200 fps animation.

I now use only my Dell 2001 fp. Will never go back to a CRT. That's not to say that the Dell is perfect. It has its flaws, including ghosting. When looking for a monitor, just go out and play with it a little. Everything has its flaws. Just ask yourself though, can you live with them?
 

Nuclear_Eclipse

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anything faster than 75Hz (15/16 ms repsonse) generally is not noticable, unless you are specifically looking for it. I have a 16ms lcd, and i never notice any ghosting unless im specifically looking for it. If you like the game enough to get into it, you could have a 25ms response time and never notice it.
 

CyberCRAP

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Actually it really depends on the person. I personally can't stand running at below 85hz on my monitor. Below that and I'll notice it after prolonged use. 85hz is about 12ms, but that is 12ms from grey to grey. So I'm thinking we probably need sub 8ms lcds to have zero ghosting. However that is just my estimate.
 

canislupy

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I've always been able to see anything less than 85hz on a CRT (and can sometimes still make out 85hz). I hate flicker. Not sure if its a product of my vision in general, or whether it can be attributed to my monocular vision (blind in my right eye). Usually the people I have asked to look at a monitor and tell me if they saw flicker said no, sometimes even at 60hz (which drives me crazy). Now, this is just CRT's mind you... I have never had a problem with LCD's at any hz or ms. All I know is its LCD's all the way for me from now on.

As an aside, being blind in one eye since birth I was always confused about how other people could see out of both eyes... stereoscopic vision, 3D movies (ha!), all that kind of stuff... I thought it was weird when someone told me that you guys could hold a finger in front of your nose and see two of them... freaks! :eek: ;) :D

Another cool thing is that my vision doesn't blur when I'm drunk. :p
 

havand

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IF i remember correctly, i saw a show on something similar to this subject one time and it was VERY interesting. Basically, the air force has conducted tests on the matter and found out the human eye is incredibly fast. They've put pilots in a totally black room and flashed images of jets at a wall at 1/220th of a second. Not only did the pilots SEE the jets, they were usually able to identify them. (thats a 4.5ms response time on a monitor)
 

Falls Included

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my old ass 17 crt is only capable of 65hz at 1280x1024, and i dont have any probs with it.. i only even notice flicker once in a while, when i look at it very quickly... but im just used to it. 85+ hz would spoil me real quick
 

dudewth

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I've noticed that I can see anything up to about 75Hz, but I do have to try a bit. My monitor is getting old, so I can see it shaking a little, but that's a bit different.

Try this out. Look up, about 2 feet above the top of your monitor. Focus on the wall or whatever is up there, but you should notice the computer screen. If you set your CRT's Hz to about 60, you should notice it flickering. One of my professors (He's EE and genetics) explained to us that the cells on the outside of your eyes are more sensitive to movement. This is one of the reasons that people usually have their best reaction times when something comes at them from the side. I usually can't see this same flickering at 85 Hz, so that's about my minimum.

canislupy said:
Another cool thing is that my vision doesn't blur when I'm drunk. :p
:p :D
 

Shadow2531

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Yeh, anything below 75Hz drives me literally insane. I cannot look at it or I'll get a instant splitting headache. Lots of people run at 60Hz and never notice the flicker. Crazy people ;)
 

DrT

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Some of this is repeated information, but I figure I'd put it all in one place:
- The eyes can detect static changes up to around 1/220th of a second (~4.5ms) or maybe even more
- Depending on motion blur, motion can be fluid at very low rates (24-60 fps)
- A large number of people can see CRT monitors flicker at under 85Hz

From my personal experiences, the response you notice changes over time. I didn't notice 60hz flicker when I was a kid, started noticing it around high school and upgraded to a display that could do 85hz (19" Sony E400), and I didn't notice any visible flicker. When I went off to college, I got a laptop with a 25ms screen, and I became spoiled by its no-flicker operation (even though it ghosts a bunch, it's only noticeable in certain circumstances). I'm now back home for the summer, and I can clearly see 85hz refresh rates.

The best course of action is to just buy the best you can afford. At the moment, that seems to be either 16 or 20ms for LCDs.
 

nightelfmaster

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so lcds are actually good cauz of pixel lag? I never thought ill say this, but pixel lag actually helps, such as in temporal AA or when the hertz isn't fast enough...
I have like a 25ms sony lcd, and i don't notice much ghosting... I think its just that either i gotten used to it, or i'm like that... I mean i move around too fast in games to actually notice the ghosting anyways... lol the only ghosting i notice is when i drag windows, and its only when it moves very fast
 

Burke Hamblin

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The last two LCDs I've owned, a 181T and a 213T both have 25ms response times and I do not notice "ghosting" of any kind. Maybe me eyes're bad.
 

emorphien

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Nytegard said:
\
What's acceptable to one person is not to another. Generally, 30 fps is considered what is needed to make smooth animation for the human eye. But there have been studies where people were able to detect single images and what they were in a 200 fps animation.
30 fps of still images (what you get with computer games) is easily noticeable. 30fps only works for movies because each frame has motion blur incorporated. You really need over 50 (the higher the better) in something like video games with individually rendered images before you stop to notice the changing of frames.
 

nightelfmaster

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for me it gets choopy if its under about 40, but thats just me... I mean i can tell the difference between 60, 40, and 75, but when u go from 60 up, it becomes harder to tell...
also on that test when they flashed the picture of the airplanes, they were probably able to c them because it left an imprint on the chemicals in your eye. If it were a regular motion show/picture, they probably woulden't be able to differientate it from the others.
 

kuyaglen

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I've been playing my games on my inspiron 8200, and it has a 25ms Ultra Sharp panel and
it does ghost when I look for it, but I only notice it on applications or when I look at skies in
games and move in a smooth steady motion, but as for noticing it during games?...nope.

I have scene terrible ghosting on some decent quality LCD screens though, particularly
Gateway LCD screens 15" to 19" and their manufacturer is LG and on their HD LCD/TV's.
 

A13X

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To all the people who claim that they "don't notice" the lag on their LCDs: good for you.

That does not change the fact that the monitor lags, and other people do "notice" it. I put that in quotations because its a gross understatement.

There is a huge difference between a 2ms response time 3ms input lag lcd and a crt, and while extra hz doesn't help much on LCDs that allready have input lag, upping the hz on a crt also greatly improves responsiveness.

When I switched from a fast lcd to an 85hz crt, aiming in cs source was so much easier I practically thought someone had installed an aimbot on my machine when I wasn't looking. Seriously, it was more like a game of "click on the heads" than struggling to pull off a headshot, if that makes any sense.
 

Snowdog

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Yeh, anything below 75Hz drives me literally insane. I cannot look at it or I'll get a instant splitting headache. Lots of people run at 60Hz and never notice the flicker. Crazy people ;)

So you can't watch movies at a theater? They generally flicker at double the the frame rate (24fps) so 48Hz.
 

Snowdog

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With the response times on LCDs becoming lower and lower nowdays the question comes up: "Where is the threshold of the human eye/brain with respect to detecting the response time of a pixel changing from one color to another, black to white or anywhere inbetween.

LCDs "numbers" are plenty fast, but part of the problem is the numbers are generally exaggerations. Plus the changes sort of merge with the next frame without a clean break.

Ideally they should flicker the backlight to give really sharp motion, but then you would have the same issues with flicker as a CRT.

If you had an LCD that could actually completely change in 4ms(which I doubt even 2ms LCDs really do), then if you blanked the backlight during that 4ms, so you wouldn't see the change and you would have retina clearing, then motions would be as crisp as a CRT.
 

Shadow2531

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So you can't watch movies at a theater? They generally flicker at double the the frame rate (24fps) so 48Hz.

No, I have no problem watching movies at a theater. Don't even have a problem watching the big cinema screen at cedar point while sitting in the first row (besides a stiff neck).
 

RPGWiZaRD

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Why do you A13X had to revive this 5 year old thread. Oo

Funny timing tho cuz I just ordered the ViewSonic VX2268wm 120Hz which I've waited like 5 years for, for me it's a huge difference between 100 and 60Hz in gaming, why I've waited this long for 100Hz+ LCDs to appear, 60Hz doesn't cut it for me for some games, for strategy games it's OK. :p Anything with lots of movements in it like FPS, racing etc I really can't stand 60Hz now when I've got used to the smooth feeling 100Hz gives.
 

nomu

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No, I have no problem watching movies at a theater. Don't even have a problem watching the big cinema screen at cedar point while sitting in the first row (besides a stiff neck).

omg...he quoted something you said 5 years ago and you responded within 15 minutes like you had said it today.
 
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Movies in the theatre don't "flicker", they're projected...Some people. CRT "flicker" is vertical redraw.
 

A13X

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Why do you A13X had to revive this 5 year old thread. Oo

Funny timing tho cuz I just ordered the ViewSonic VX2268wm 120Hz which I've waited like 5 years for, for me it's a huge difference between 100 and 60Hz in gaming, why I've waited this long for 100Hz+ LCDs to appear, 60Hz doesn't cut it for me for some games, for strategy games it's OK. :p Anything with lots of movements in it like FPS, racing etc I really can't stand 60Hz now when I've got used to the smooth feeling 100Hz gives.

I didn't revive the thread, someone else did.

But anyway, yeah i tried the 120hz samsung and wasn't impressed. There appeared to be less ghosting than 60hz screens, but it didn't feel any more responsive than the 60hz TN i had at home, and wasn't anywhere near crt speed. Even 75 hz felt much faster on a CRT. Then again that was just the samsung... the viewsonic could be different but from what i've read they both have input lag.
 

vick1000

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It is completely dependant on the source bieng viewed. Liquid Crystals changing form to change the color of the light bieng passed through is completely different than an electron gun charging phosphors on a CRT mask, or moving frames of a film.

The way your eye percieves the light and darkness and the changes of those factors, are what determine if you percieve blurring. The eye will inhernetly retain some part of teh image when shifting between dark and light images, so your brain will always percieve some blurring in those cases.
 

Inu

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Let's just hope OLED Technology promises to improve things in some way the technology works. Since SEDTV Will never make it through the legal crap.
 
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