Peripheral Vision Flicker on Monitor
krumins george
Is the video card driving the monitor in interlaced mode?
David Detienne (deti...@elen.utah.edu) wrote:
: I just got a new monitor (that I'll be sending back). If you stare
: at one spot on the screen it is fine, but icons just a couple cm away
: look like they are wiggling up and down. The effect is consistent
: anywhere you look on the screen. I did a survey with coworkers, and
: those older than 40 years couldn't see it, but younger people could
: see it. So it seems to be a peripheral vision flicker that only
: "younger" people can see. What is causing this?
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Mark F. Flynn
deti...@elen.utah.edu (David Detienne) writes:
>I just got a new monitor (that I'll be sending back). If you stare
>at one spot on the screen it is fine, but icons just a couple cm away
>look like they are wiggling up and down. The effect is consistent
>anywhere you look on the screen. I did a survey with coworkers, and
>those older than 40 years couldn't see it, but younger people could
>see it. So it seems to be a peripheral vision flicker that only
>"younger" people can see. What is causing this?
It's not peripheral vision flicker, jut plain old flicker, which is more
noticeable to peripheral vision. (Probably a rods versus cones thing).
But don't be so fast to blame your monitor. What you need to do is find
out what is the maximum refresh rate your monitor AND graphics card can
support at the resolution you are showing. You want 70 Hz or better. So
the problem could be the card, the monitor, both, or it could be that
you just need to adjust the settings.
Mark Flynn
==Kaiser Electronics ==phone: (408) 432-3000 x1091
==2701 Orchard Park Way ==Fax: (408) 432-8440
==San Jose CA 95134 ==email: fly...@kaisere.com
David Detienne
unk
In article <504pud$i...@news.cc.utah.edu>, deti...@elen.utah.edu says...
faster (more sensitive to light). The eye integrates the image on the retina
for a fraction of a second in order to collect ligth and reduce noise. The
more sensitive periferial vision need not collect for as long as the center
part of the visual field i.e. it can see faster variations.
In the center the flickering image fuses to a continous picture in time, but
not in the periferial field.
I think that the ambient ligth play a part in this also because in low ligth
conditions the fusing time increases (dark adaption). Do experiments!
decrease the ambient ligth or image brigthness an see what happends.
/Regards
Peter Weijnits
e-mail pe...@physto.se
William C. Snyder
David Detienne wrote:
>
> I just got a new monitor (that I'll be sending back). If you stare
> at one spot on the screen it is fine, but icons just a couple cm away
> look like they are wiggling up and down. The effect is consistent
> anywhere you look on the screen. I did a survey with coworkers, and
> those older than 40 years couldn't see it, but younger people could
> see it. So it seems to be a peripheral vision flicker that only
> "younger" people can see. What is causing this?
My guess is that the "up-and-down" flicker is due to an interlaced
display mode. This usually occurs with icons which have small structure
that "dissappears" during one of the two half-frames. Non-interlaced
flicker is annoying to many people when it's rate is below 70 Hz. An
interlaced mode can have 90 Hz half-frames, and thus 45 Hz full frames,
well below the perception limit. Any horizontal structures ( size = one
scan line ) will modulate at the slower 45 Hz and be distracting. Solid
structures will not be objectionable.
The well-known test for refresh-rate flicker (in contrast to interlace
flicker) is to pull up a white screen (like in a blank word processor
page) and look at the monitor out of the corner of your eye.
The flicker or interlace depends on your video card mode. Many video
cards and monitors allow more than one mode. The modes that are possible
depend on the capabilities of the monitor and card. Plug and Play with
Windows95 (if that what you are using) will try to adjust the mode to
what it thinks is the best possible, but if the monitor is not PnP, this
may not happen. You need to check the monitor literature and the card
literature to see if there is a non-interlaced mode at the desired
resolution which has a refresh rate at 72 Hz or above. Almost all
monitors and cards these days can do 72 Hz, 768 X 1024 X 256 colors.
Unless you got a bottom of the line monitor you probably don't need to
return it.
Note that I cheerfully paid an extra few hundred dollars to get 90 Hz
non-interlaced performance. I believe that one shouldn't operate at just
above the perceptable limit, but comfortably above it.
-Will
--
Dr. William Snyder
wi...@icess.ucsb.edu
http://www.icess.ucsb.edu/~will/will.html
Imaging Scientist
Institute for Computational Earth Systems Science
University of California Santa Barbara