# Eyes Resolution & Monitor Pixel Size

Discussion in 'Digital Photography' started by Hughes, May 6, 2009.

1. ### HughesGuest

Hi,

I wonder if this is just a coincidence or design.

Human eyes have a average resolution of 60 arcseconds for brightly
illuminated target.

My monitor has a pixel pitch of 0.264mm.
When I view it at a distance of of 800mm (0.8 mtr). The 0.264mm pixel
subtends at an angle of
theta = 2 arctan (0.5 (0.264)/800) * 206265
= 68.07 arcsec

The angle of the pixel subtended at a viewing
distance of 0.8 mtrs is 68 arcseconds close to
human eyes resolution of 60 arcseconds. Is this
just a coincidence or did they make the pixel
size of the monitor to match the resolution
specification of human eyes by design?

Hughes

Hughes, May 6, 2009

2. ### Ray FischerGuest

Higher resolution is expensive. It makes sense that people would a
monitor that is as sharp as they can see but not more expensive than
needed.

Evolution in action.

Ray Fischer, May 6, 2009

3. ### whisky-daveGuest

Not all monitors are the same.
I view mine at about 500mm

The 0.264mm pixel
If you take your 800mm that's 31.49 inches.
That's about 10 times pi . but so what.

What makes you think 800mm has any meaning.
If such a meaning was meant surely they'd set distance of 1 metre
a true SI unit.
Playing with numbers can prove anything, i.e Captain Kirk caused 911

Well the numbers in 1701 add up to 9 the first and last are 1s 911
The word Enterprise has 9 letters, and there's 11 in captain Kirk . 911

Coincidence well some don't think so, but they are, or should be
in specially padded homes and kept away from sharp objects ;-)

whisky-dave, May 6, 2009
4. ### mcescherGuest

mmmmm, pi......

mcescher, May 6, 2009
5. ### Don StaufferGuest

If the monitor were designed for one specific application then it may be
design. But for a general purpose monitor, it is somewhat a combination
of coincidence and design.

Say I were designing a cockpit display for a military aircraft with a
night vision device such as a flir. Then the acuity of the operator
WOULD be a design factor.

However, for general commercial monitors there would be some effort to
determine what normal viewing distances are, and to avoid too high a
resolution that goes beyond the viewers acuity, but that would not be
the main driver. More to the point would be a cost-quality tradeoff.

In essence, many years ago, monitor resolution did not match- one could
see the pixels plainly. As TV and monitor business grew and involved
more money, there was a big effort to improve resolution, and of course
in TV systems the advent of HD standards. Eventually the performance
equaled or exceeded the needs based on acuity, and there is no longer
such a push for finer and finer ppi. Rather, the other factors,
brightness, contrast and color purity are now the big efforts.

Don Stauffer, May 6, 2009
6. ### HughesGuest

This may be why they say there is not much difference
in watching 720P vs 1080P HDTV shows at home at a normal sitting
distance because the 1080P pixels and
their separations are so small that our eyes 60 arcsecond resolution
can no longer detect them (maybe needing 20 arcsecond to see the
pixels separations). So there may
be no need for 2160P HDTV years from now unless
people get to see TV the same distance as viewing
monitors.

H

Hughes, May 6, 2009
7. ### Chris.BeeGuest

History records that the flat screen computer monitor is merely a
development of the common CRT TV from the infancy of computers. (ZX81
and BBC and vast rooms full of (mostly) white coated men using punched
card sorters and giant reels of tape)

It is quite amusing now to see science fiction programmes and films
displaying large numbers of B&W CRT screens in "futuristic" space
ships. If each new generation's tools and toys are magic to the
last.. what do we have in store in the next?

I wonder whether there will ever be a general move towards displays
attached to the head itself? I doubt that "special glasses" will take
off. Too many negative social aspects. Perhaps a direct connection to
the optic nerve or the brain itself by some means of inductance or
skin conductance? A projected 3D hologram? A permanent brain implant,
heads-up display with GPS, TV, film, radio, communication and
broadband? It sounds quite stressful! ;-)

Chris.Bee, May 6, 2009
8. ### Jürgen ExnerGuest

See "Richter 10" by Arthur C. Clark. He calls it "chipped" if I remember
correctly. Written in 1996 he was pretty good at forecasting the
proliferation of cameras everywhere, not implanted yet but many people
indeed can't live without their cell phones and blogs and spaces and
texting and sexting and ... any more.

jue

Jürgen Exner, May 6, 2009
9. ### OfnutsGuest

Monitor resolution ranges, due to market constraints, from "barely
readable" (around 50dpi) to "we can make it more expensive but noone
will see the difference" (around 200dpi). Sometimes there are
explanations for miracles or even mere coincidences.

Ofnuts, May 6, 2009
10. ### Dr J R StocktonGuest

In sci.astro.amateur message <
Never quote an author whose name you are unable to spell correctly.

"Richter 10" was co-authored, and probably largely written, by Mike
McQuay.

Dr J R Stockton, May 7, 2009
11. ### Kennedy McEwenGuest

God how I WISH you were right!

As someone who designs the FLIRs that produce images on those monitors,
I am sorry to say that you are very wide of the mark.

The drivers for selection of those monitors are, in order:
Cost
Size
Cost
Direct sunlight visibility
Cost
Weight
Cost
Power dissipation
Cost

I think I might have underplayed the importance of cost. ;-)

Seriously, you only have a limited amount of space in a cockpit to fit a
video display and it will be further from the pilot than you would like,
so its practical resolution to the operator is always going to be well
below SD TV standards, even if the display itself is much higher. Then
there is aircraft vibration to consider. By the time its all added up,
most of the time they can't tell the difference between Q-VGA and 720p
HD! There are a couple of exceptions, where the image is not presented
to just the pilot, but that is generally the case.

Kennedy McEwen, May 8, 2009
12. ### Chris.BeeGuest

"Never" was a bit strong, JR, and your tone quite unwarranted despite
your hero-worship of said author.

Notwithstanding the typo, Jürgen's information was both useful and
included the source.

Will a simple flogging do?

Or shall we chop of his hands before relieving him of his head?

Perhaps you were hoping for the head as your prize to show off at
Stockton Towers?

Dare I suggest a search for <tact & tone> ?

Chris.Bee, May 8, 2009