Is there a limit to what we can see?

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John Doroshenk
With all the talk about HD VHS and HD-DVD and the claims of beauty that is being displayed, is there a limit to how much we can visionally comprehend. I mean I've seen some hd content and its amazing, but can they really improve on that and do you think you'd be able to tell. It seems to me at some point there would be limit reached on visual improvements. Is HD-DVD with the best compression technology and laser the end. Or is there something more beyond that? I think it could be the end, at least in my mind, and the only changes will be in storage capacity to increase content and audio types (more speakers full bitrates) and size of the media. Any thoughts on this. Do you agree or do you think our enternal persuit of upgrade envy will continue.

John
 

Adam Barratt

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I think it's unlikely in the extreme that HDTV will be the last advancement in video we see. HDTV is well short of matching film, let alone the absolute capabilities of human visual perception.

I imagine it will be quite some time before any readily-available technology is truly capable of approaching either of these.

Adam
 

Cees Alons

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Yes, like Adam said, there's a physical limit. It's the size and distance of the cells in our retina (approx. 5 micron).
The next thing you have to know is: how far will you be from the viewing screen? This is a slightly more difficult question, because it has to deal with related questions, like: do you want to see all of the picture in your viewing area (I think most of us will). When do you consider necessary eye/neck movements as inacceptable (angle?), etc.
If we assume a 1:1 ratio (distance-to-screen : width-of-screen) as the widest acceptable angle (most people will say: that's too close!), then there's no sense whatsoever to increase the resolution ever to more than (roughly) 3000 distinctive horizontal pixels.
If you think you should sit further away / closer, you may decrease/increase this number according to ratio.
(If you're never closer to your screen than 4x its width, DVD is all your eyes need
.)
Cees
 

Joseph DeMartino

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I mean I've seen some hd content and its amazing, but can they really improve on that?
Look at the HD content on a store display, then look at the real objects and people around you. Until the day you can't tell the difference between the two, there will be room for improvement.

Regards,
Joe
 

wally

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Look at the HD content on a store display, then look at the real objects and people around you. Until the day you can't tell the difference between the two, there will be room for improvement.
Then you plug-in direct, like Matrix or Brainstorm.

BTW, anyone know anything about the Brainstorm release? Amazon doesn't even have the ratio listed.
 

DaveF

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Yes, there is a fundamental limit to what we can perceive. The eye's angular resolution is about 1 arc-minute (which is related to the cones-size Cees mentioned).
Here's a few tidbits about the eye

- Most of the focusing power comes from the cornea. The lens provides accomodation so we can see things far and near.
- Around 45 yrs, the lens crystalizes -- can't flex anymore -- and you can no longer accomodate. This is presbyopia, and why "old" people
wear reading glasses, bifocals, etc.
- The "fovea" is the area of the retina with the highest concentration of cones (color-detecting cells), and provides our highest resolution vision. This is pretty much in the center of our vision.
Cool stuff:
There is some really cool research being done (including here at the U of R), combining adaptive optics (from astronomy) and retinal imaging (from visual science) that allows nearly perfect pictures of the retina. Before, you could either get good-quality pictures of dissected eyes' retinas, or you could get low-quality images of "living" eyes. Now, you can get high-res images of living eyes.
Even better, this system can be made to work in reverse -- the person being measured can be "given" perfect vision, by removing all the optical aberrations of their lens. This is like a perfectly tailored pair of glasses.
Alas, this is all still research equipment. Adaptive Optical glases won't be at Lens Crafters anytime soon. But this research could eventually help with corrective surgeries and phthalmic lens fabrication.
Concievably, the average person's visual limits could be taken to the fundamental limit in the future!
Ok, class dismissed
 

Jack Briggs

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Now, class, there will be a test on Monday. Print the thread out and study it over the weekend. Thank you.
 
M

MaxY

John,
Take a Careful look around you, put your hand in front of your face and really look at it.
When HDTV looks that good, it has reached the limit.

Max
 

Mike Miskulin

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And let's not forget the good ol' Wavefront Lasik technology currently being studied in Canada (otherwise known as America, Jr.
). With this refractive surgery, one could conceivably be able to see 20/6 (basically, the limit of perceptable human site). Some people who've had the surgery done successfully have even complained of their site being too perfect. They could perceive the pixelation on television sets better then ever before, and viewing pleasure was decreased substantially...Another argument for the immediate implementation of nationwide HD broadcasts!
Long term results are still pending.
mike. (the resident optometrist)
 

DaveF

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Ok, more fun info (This is from books on my desk; I didn't know this stuff off-hand.)
  • Retina has 6M cones and 120M rods
  • Cones in the fovea are 1.5µm dia and 2.5µm apart. Rods are 2µm dia
  • Field of vision is 150° high and 210° wide. Binocular FOV is 130° dia.
  • Rods & Cones are more sparsely space in outer regions of retina
  • The eye works in illumination spanning >4 orders of magnitude: moonlit night to noon sun
  • The retinal image is upside down. This was first propounded by Kepler in the 17th century
  • Ultimate (angular) resolution is roughly 1 arc-minute, according to either the cone size and spacing, or by wave-optics theory. This also generally agrees with comments from Dawes (1867), Hooke (1680), and controlled experiments.
Ok, time for some math. Hold on, it's a wild ride
(Van Patton, you paying attention? Here's some real-world Trig.)
D = 1 arc-min
R = D arc-min / (60 arc-min/deg) * pi / 180 = 0.3 milli-radians
The smallest point resolvable is:
h = L * D
where h is diameter of the spot, and L is the distance away from the spot (Draw an isosceles triangle. D is the angle of the peak. L is the height. h is the base.)
So, 10 feet from TV
10 ft => 3 meters
h ~= 1 mm ~= 4/100 inches
That's a few hairs side-by-side
In the movie theater, sitting 30 feet from the screen
h ~= 10 mm ~= 1/2 inch
Of course, this is all idealized, and are "ultimate" values. Everything else being perfect, you're not going to beat this resolution, without defying the laws of physics. So, there is no use in designing past these values. I'd make a wild guess that a factor of 10 larger (poorer resolution) is still practically an extreme design goal.
I'll leave it to the reader to compare these gibberish to film-grain size and television pixel size.
Bring your #2 pencils to class on Monday, for the quiz
 

Cees Alons

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I'll leave it to the reader to compare these gibberish to film-grain size and television pixel size
Dave, I've already done that (see above). If the screen is as wide as your distance to it (3 meters), then pixels at 1 mm amount to a total of 3000 pixels along the horizontal axis of the screen.

Cees
 

Christian Dolan

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This is interesting, considering how much time we spend on aspect ratios.

From DaveF’s figures (210 degrees horizontal by 150 degrees vertical), the visual field of the human eye has an inherent “ratio” of 1.4:1, just shy of the thinnest widescreen ration that I know of, 1.66:1.

-Christian
 

David Ruiz

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I too have seen HD on display at stores like Best Buy & Circut city, and I can say that it is a LOT more room for improvement. HD, looks nowhere near as good, as FILM does. Until HD, can reach the resolution that FILM has, that's when the limit will be reached.

I will admit that HD is in the right direction, though.
 

Cees Alons

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Christian,

But that's not the way you look. You don't fix your eyes on the center of the screen, and be able to view the whole image then. Your eyes (gaze) have to move all over the screen, because you can only see sharp enough in the centre of your retina.

And there's much more movement possible in the horizontal plane than it is in a vertical direction.

Cees
 

Artur Meinild

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I think it's unlikely in the extreme that HDTV will be the last advancement in video we see. HDTV is well short of matching film, let alone the absolute capabilities of human visual perception.
However, since digital filming now is HD resolution (Star Wars Episode 2 for example) and since "only" HI-DEF transfers are made of current films, one could say that HIDEF will be the limit for a certain amount of films at least.
 
M

MaxY

Yes there are limits on what you can see.
The MPAA is constantly limiting what you can see with their uneven ratings. Then there is local decency laws that again limit what you can see and then there are ever a few national laws regaurding content as well.

Max
 

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