human eye refresh rate

[fire400]

RE: Yeah...
By scrapsma54 on 11/9/06, Rating: 2
By scrapsma54 on 11/9/2006 5:39:56 PM , Rating: 2

overclocking? I wouldn't doubt it. However, The human eye sees
life at a refresh rate of 60hz; jumping it further requires a huge modification to the human brain. This would be usefull in soldiers. seeing at a rate of 200hz would ultimately make soldiers see bullets in slow motion. The drawback would be self explanitory. Also watching television would be like watching a slide show. I have heard something about placing neodymium magnets in a incision and when the wound heals the magnet can pick up electric charges and the nerve tissue picks them up. The drawback is the coating would crack and the implant would have to be replaced. Scientists are working on a more durable coating.

http://www.dailytech.com/article.aspx?newsid=4653

some kid posted this, and I was wondering how true the soldier statement and the TV statement would be should a development actually exist in the future.

someone please clarify, thx-

 

[Cattlegod]

I had always assumed the human eye never had a "refresh rate" but more a blurring effect when something moves too fast (i.e. like an LCD screen).

 

[fire400]

Originally posted by: Cattlegod
I had always assumed the human eye never had a "refresh rate" but more a blurring effect when something moves too fast (i.e. like an LCD screen).

you mentioned LCD screen, would a plasma screen do much better?

 

[Kreon]

That'd be pretty cool...

But to see things in slow motion, wouldn't that mean that the brain would speed up, along with the eye?

Just a thought from a not expert

If it works, another technology to turn humans into more deadly killing machines, what a lovely world we live in, everything becomes a weapon...

 

[bobsmith1492]

We were just talking about this in DSP class. We were talking about aliasing, and I mentioned how the low sampling rate in videos makes fast moving objects like wheels and helicopter blades seem to be moving backwards, slowly, or not at all. Prof said he thought he noticed the same thing even when there was no apparent sampling source (i.e. when outside in full sunlight).

Has anyone ever noticed aliasing effects (slow motion wheels) when outside on a sunny day, or does it just blur?

 

[wantedSpidy]

We have no 'sampling' rate as such. Our body does processes continuous signals. Since most electronics cannot handle conituous signals (in order to keep the math simple), we samlple real signals at a certain rate, to get a discrete signal which represents the original signal.

As for seeing aliasing with the naked eye, it doesn't matter if the signal is continuos or discrete, in order for there to be aliasing. Its just that when we talk about signals in the frequency domain it gets easier to graphically see what happens when there is aliaing in a signal.

does that make sense? damn, I need to take a class in technical writing .....

 

[SuperFungus]

I've definately noticed 'slow motion wheels' on a sunny day before, even ones that seem to be going backwards, and often wondered how it happens. So your prof isn't alone on that bobsmith.

 

[herm0016]

i agree. when looking at airplane propellers they seem to go backward, than change direction. all while in reality just changing speed. seems as if we do have a "refresh rate" i wonder if its a function of the eye or the brain?

 

[CycloWizard]

The controlling variable here is called a 'flicker fusion rate' (or, 'flicker fusion frequency'). At frequencies higher than this rate, the human eye/brain complex will see an 'analog' image, whereas below this rate, humans will see 'blanks' or merged images, depending on how the image is presented to the eye.

Why does this happen? Because, though the photochemical isomerization reactions that govern light detection in the retina are an analog process, the result of temporal summation of these reactions is a discrete action potential (i.e. an electric depolarization/hyperpolarization of the nerve cell). The frequency of action potentials is controlled by the light intensity and wavelength. Thus, though the light entering the eye is essentially an analog stimulus, the response that our brain sees is still discrete in nature.

Edited to add links.

 

[gsellis]

scrapsma54 does not seem to know humans. I think he is thinking that we can notice flicker on a monitor at 60hz and thinks that is how our brain functions. That flicker 'detection' is caused by the 60hz flicker with florescent lighting working like a strobe and highlighting the scan rate on the monitor.

The human eye has a rate of about 30 frames per second. Anything faster and our brain fills in the gaps. Some humans go a bit faster (the first pulsar was discovered by a woman touring Lowell Observatory - she asked why it was blinking and they shrugged her off as a loon - years later, the star in question was found to be pulsing at 30fps and they immediately remember that one woman who goes uncredited - that was at least the story they told us at Lowell when we toured )

As for 200hz/fps/whatever - "seeing in slow motion"? No matter how well you can see it, it still is moving at 2000+fps most likely. Wow, you almost sense the bullet that kills you. There is no way to react to it, but hey, you could see if it really had your name on it. The advantage might come in being able to tie it to a computer and use the ballistics track to localize the source. That could be a passive system and harder to detect* than something like "personal radar".

* harder to detect? A passive system? That should be impossible! Not. One of the things they do with weapons systems is test them for signature emissions. The electronics in a weapon will make electronic noise. If poorly designed, someone could listen for it and pinpoint its source to destroy it. Worse, listen to it and steal its information. Fictional example, you listen for an enemies radar gear. Forget the signal, you detect the console's signature and they did a bad job on cutting the RF on it. Wow, I can grab their radar screen and see their IFF to detect MY targets and see if they see me.

 

[Gibsons]

Originally posted by: gsellis
scrapsma54 does not seem to know humans. I think he is thinking that we can notice flicker on a monitor at 60hz and thinks that is how our brain functions. That flicker 'detection' is caused by the 60hz flicker with florescent lighting working like a strobe and highlighting the scan rate on the monitor.

The human eye has a rate of about 30 frames per second. Anything faster and our brain fills in the gaps. Some humans go a bit faster (the first pulsar was discovered by a woman touring Lowell Observatory - she asked why it was blinking and they shrugged her off as a loon - years later, the star in question was found to be pulsing at 30fps and they immediately remember that one woman who goes uncredited - that was at least the story they told us at Lowell when we toured )

As for 200hz/fps/whatever - "seeing in slow motion"? No matter how well you can see it, it still is moving at 2000+fps most likely. Wow, you almost sense the bullet that kills you. There is no way to react to it, but hey, you could see if it really had your name on it. The advantage might come in being able to tie it to a computer and use the ballistics track to localize the source. That could be a passive system and harder to detect* than something like "personal radar".

* harder to detect? A passive system? That should be impossible! Not. One of the things they do with weapons systems is test them for signature emissions. The electronics in a weapon will make electronic noise. If poorly designed, someone could listen for it and pinpoint its source to destroy it. Worse, listen to it and steal its information. Fictional example, you listen for an enemies radar gear. Forget the signal, you detect the console's signature and they did a bad job on cutting the RF on it. Wow, I can grab their radar screen and see their IFF to detect MY targets and see if they see me.

Which would mean a smart military should invest in Faraday cages of all shapes and sizes. Maybe I should invest in some copper futures....

 

[CycloWizard]

Originally posted by: gsellis
scrapsma54 does not seem to know humans. I think he is thinking that we can notice flicker on a monitor at 60hz and thinks that is how our brain functions. That flicker 'detection' is caused by the 60hz flicker with florescent lighting working like a strobe and highlighting the scan rate on the monitor.

The human eye has a rate of about 30 frames per second. Anything faster and our brain fills in the gaps. Some humans go a bit faster (the first pulsar was discovered by a woman touring Lowell Observatory - she asked why it was blinking and they shrugged her off as a loon - years later, the star in question was found to be pulsing at 30fps and they immediately remember that one woman who goes uncredited - that was at least the story they told us at Lowell when we toured )

This really depends on how the images are presented to you. In a TV sense, the flicker fusion rate is about 25 Hz, which corresponds to about 50 Hz (because each frame gives more than one stimulus impulse). This is why TVs refresh at 30 Hz (really, 29.97) - this is high enough to avoid the flicker fusion rate without being so high that it wastes energy creating excess frames. If you're in Europe where the power cycles (or, at least, used to cycle) at 50 Hz, many people can see the lights flickering. Here in the US, everything is run at 60 Hz. Still, some people can detect flickering because some peoples' brains process things faster than others, some peoples' nerves conduct more rapidly, and some peoples' photoreceptors have better electrical coupling with their corresponding nerves.

As for the refresh rate of a monitor, I can tell you anecdotally that, even in the absence of other light sources (i.e. only my monitor is turned on), I'll get a headache if I use a computer at 60 Hz for a prolonged period. I can also tell when gaming if my framerate starts to drop below 120 Hz. This is because the discrete signals going to my brain have fewer impulses and behave somehwat irregularly due to the 'chopiness' of the resulting signal. My brain has a hard time dealing with this irregular input and has to work harder to form an image.

 

[randay]

just activate your third eye.

 

[Smilin]

Despite the fact that flickering may seem to disappear to us above ~75hz this does not mean our perception is bound to 75fps.

Military testing of pilots found they could identify an aircraft when shown an image for 1/240th of a second.

To see with your own eyes what I mean, find a rapidly moving object like a fan (ceiling fan, desk fan, propeller). Look at it and flick your eyes away and then back. Try a couple times. You WILL see the otherwise blurred fan frozen in space ever so briefly. So briefly you can only 'remember' seeing it frozen but it does indeed happen.

 

[bobsmith1492]

Originally posted by: gsellis
scrapsma54 does not seem to know humans. I think he is thinking that we can notice flicker on a monitor at 60hz and thinks that is how our brain functions. That flicker 'detection' is caused by the 60hz flicker with florescent lighting working like a strobe and highlighting the scan rate on the monitor.

The human eye has a rate of about 30 frames per second. Anything faster and our brain fills in the gaps. Some humans go a bit faster (the first pulsar was discovered by a woman touring Lowell Observatory - she asked why it was blinking and they shrugged her off as a loon - years later, the star in question was found to be pulsing at 30fps and they immediately remember that one woman who goes uncredited - that was at least the story they told us at Lowell when we toured )

As for 200hz/fps/whatever - "seeing in slow motion"? No matter how well you can see it, it still is moving at 2000+fps most likely. Wow, you almost sense the bullet that kills you. There is no way to react to it, but hey, you could see if it really had your name on it. The advantage might come in being able to tie it to a computer and use the ballistics track to localize the source. That could be a passive system and harder to detect* than something like "personal radar".

* harder to detect? A passive system? That should be impossible! Not. One of the things they do with weapons systems is test them for signature emissions. The electronics in a weapon will make electronic noise. If poorly designed, someone could listen for it and pinpoint its source to destroy it. Worse, listen to it and steal its information. Fictional example, you listen for an enemies radar gear. Forget the signal, you detect the console's signature and they did a bad job on cutting the RF on it. Wow, I can grab their radar screen and see their IFF to detect MY targets and see if they see me.

I can easily see 60Hz flicker - monitors with 60Hz refresh rates and fluorescent light bulbs reaaaaaly bug me, trust me. It's worse out of the corner of your eye as peripheral vision is much quicker, apparently.

 

[CycloWizard]

Originally posted by: Smilin
Despite the fact that flickering may seem to disappear to us above ~75hz this does not mean our perception is bound to 75fps.

Military testing of pilots found they could identify an aircraft when shown an image for 1/240th of a second.

To see with your own eyes what I mean, find a rapidly moving object like a fan (ceiling fan, desk fan, propeller). Look at it and flick your eyes away and then back. Try a couple times. You WILL see the otherwise blurred fan frozen in space ever so briefly. So briefly you can only 'remember' seeing it frozen but it does indeed happen.

Like I said, the flicker fusion rate is dependent on how the image is presented to you. The experiment you describe is a true transient response (really, an impulse) rather than the steady state behavior that we hope to achieve when using computer monitors and TVs. As with most things, transient behavior is a lot more complicated, but the same principles apply.

 

[CTho9305]

Originally posted by: gsellis
The human eye has a rate of about 30 frames per second. Anything faster and our brain fills in the gaps.

Interesting claim... download all the files in this directory, run the program, and let me know if you still feel the same way.

 

[bobsmith1492]

Originally posted by: CTho9305

Originally posted by: gsellis
The human eye has a rate of about 30 frames per second. Anything faster and our brain fills in the gaps.

Interesting claim... download all the files in this directory, run the program, and let me know if you still feel the same way.

Slick program! 60FPS looks better even than 45-50 FPS...

 

[IEC]

Originally posted by: bobsmith1492

Originally posted by: CTho9305

Originally posted by: gsellis
The human eye has a rate of about 30 frames per second. Anything faster and our brain fills in the gaps.

Interesting claim... download all the files in this directory, run the program, and let me know if you still feel the same way.

Slick program! 60FPS looks better even than 45-50 FPS...

Comparing 90FPS to 60FPS I can still see a significant difference. I can still see the difference between 120FPS and 90FPS, but it's barely noticeable. Anything above about 45FPS doesn't bother me, though I'd much prefer 75FPS+

I can't stand televisions - it's like watching a flickering slideshow

Edit: Or any other CRT-based device at <75Hz

 

[bobsmith1492]

Originally posted by: ariafrost

Originally posted by: bobsmith1492

Originally posted by: CTho9305

Originally posted by: gsellis
The human eye has a rate of about 30 frames per second. Anything faster and our brain fills in the gaps.

Interesting claim... download all the files in this directory, run the program, and let me know if you still feel the same way.

Slick program! 60FPS looks better even than 45-50 FPS...

Comparing 90FPS to 60FPS I can still see a significant difference. I can still see the difference between 120FPS and 90FPS, but it's barely noticeable. Anything above about 45FPS doesn't bother me, though I'd much prefer 75FPS+

I can't stand televisions - it's like watching a flickering slideshow

Edit: Or any other CRT-based device at <75Hz

Ya, my refresh rate limits me to 60 (LCD) - maybe I can bump it up, though...

 

[CycloWizard]

Originally posted by: bobsmith1492
Ya, my refresh rate limits me to 60 (LCD) - maybe I can bump it up, though...

Somewhat unrelated question, but what does the refresh rate of an LCD really control? Is it the frequency of the backlight? The pixel update rate? I never really read anything about this, since I'm still too poor to worry about buying an LCD (still sporting my 8-year-old 17" CRT ).

 

[imported_Seer]

The backlight is always on, it doesn't change. I think it might be the pixel update / sampling rate.

Anyone know how to get that program running above 60 Hz? No matter what resolution / refresh I set in Nv control panel, it changes it to 640x480 automagically.

 

[CTho9305]

Originally posted by: Seer
The backlight is always on, it doesn't change. I think it might be the pixel update / sampling rate.

Anyone know how to get that program running above 60 Hz? No matter what resolution / refresh I set in Nv control panel, it changes it to 640x480 automagically.

The README file has contact info at the bottom - maybe the author still has source code. Unfortunately, the URL for the "skeleton" code he worked from no longer exists.

 

[bobsmith1492]

Yeah it looks like if Vsynch is on, the program is limited to either half of the screen refresh rate or full, and some areas where it is fully adjustable. If you turn off Vsynch, it's much more controllable (and runs up to 200 FPS!)

Also, the readme says it's made for 640x480 only.

LCD refresh rates are the rate at which the pixel positioning is updated, I'm pretty sure.

 

[Born2bwire]

Originally posted by: bobsmith1492
Yeah it looks like if Vsynch is on, the program is limited to either half of the screen refresh rate or full, and some areas where it is fully adjustable. If you turn off Vsynch, it's much more controllable (and runs up to 200 FPS!)

Also, the readme says it's made for 640x480 only.

LCD refresh rates are the rate at which the pixel positioning is updated, I'm pretty sure.

If I recall correctly, triple buffering will help with Vsync when it has to drop below the full refresh rate.