Monitor Resolution Conundrum

[Box134]

I have a Viewsonic A90f+ monitor which I've grown to hate. It's supposed to
be "optimized," (whatever that means) for 1280 x 1024. The best refresh rate
I can get at that resolution is a measly 75 Hertz.

I was just mucking around, playing with different resolutions, and I found
one at 1360 x 768. Now the interesting thing is I can pump this monitor up
to 85 or 100 Hertz. The picture is nice and stable but one thing.... my
digital pictures are all out of proportion. Text seems to adapt and looks
good, icons are distorted.

So I'm wondering, is there any way around this? Is it a case of either/or?
Is there no way to use a resolution with a high refresh rate and have
correctly proportioned images too? Is this a limitations of WinXP? Who would
use resolutions of 1360 x 768 anyhow? Maybe a monitor with a different
aspect ratio?

 

[Bob Myers]

I have a Viewsonic A90f+ monitor which I've grown to hate. It's supposed to
be "optimized," (whatever that means) for 1280 x 1024. The best refresh rate
I can get at that resolution is a measly 75 Hertz.

It's measly only if you can really see flicker at that
rate. If not, what's wrong with 75 Hz? This is NOT
a case of "faster is always better."

I was just mucking around, playing with different resolutions, and I found
one at 1360 x 768. Now the interesting thing is I can pump this monitor up
to 85 or 100 Hertz.

Sure; with only 768 active lines per frame - and probably right
around 800 lines total - you don't run out of horizontal frequency
range until you get to these higher refresh rates. But there is
almost certainly zero benefit to be had at running faster than
85 Hz. Somewhere in the 80-85 Hz range, you've hit the point
where over 95% of the population can no longer detect flicker
under typical monitor viewing conditions.

The picture is nice and stable but one thing.... my
digital pictures are all out of proportion. Text seems to adapt and looks
good, icons are distorted.

Sure they are. 1360 x 768 is almost a 16:9 aspect ratio, and
you're probably trying to display it full-screen on a 4:3 CRT -
which means the image is SEVERELY compressed horizontally.
In other words, you have too many pixels per line, yet Windows,
in drawing the icons, text, etc., is still assuming that the pixels are
"square" (meaning the you have the same number per inch
horizontally as vertically). If you want an undistorted full-screen
image at these rates, your only option is to go back to the good ol'
"XGA" format - 1024 x 768 pixels. Or you might try an intermediate
format; 1280 x 1024 isn't a good match to a 4:3 tube in the first
place (it's 5:4), so how about 1280 x 960 (which would let you up
the refresh rate a bit higher than 75, if you insist), or perhaps something
like 1152 x 864.

Bob M.

 

[Box134]

It's measly only if you can really see flicker at that
rate. If not, what's wrong with 75 Hz? This is NOT
a case of "faster is always better."

No, it's not a macho thing..... my old eyes definitely prefer 85 Hz, more if
they can get it.

Sure; with only 768 active lines per frame - and probably right
around 800 lines total - you don't run out of horizontal frequency
range until you get to these higher refresh rates. But there is
almost certainly zero benefit to be had at running faster than
85 Hz. Somewhere in the 80-85 Hz range, you've hit the point
where over 95% of the population can no longer detect flicker
under typical monitor viewing conditions.

Some people say low frequencies can affect your eyes, even if you can't
detect flicker. I don't know if that's true or not. Read an interesting
thing about cats ( I'm not a cat ) which claimed some cats can't see
anything on a TV screen because they process so fast all they see is a
moving point of light.

If you want an undistorted full-screen
image at these rates, your only option is to go back to the good ol'
"XGA" format - 1024 x 768 pixels. Or you might try an intermediate
format; 1280 x 1024 isn't a good match to a 4:3 tube in the first
place (it's 5:4), so how about 1280 x 960 (which would let you up
the refresh rate a bit higher than 75, if you insist), or perhaps something
like 1152 x 864.

Just by coincidence, after computing ratios, I did decide independently that
1280 x 960 was best for this screen because it does match the ratio of the
display dimensions which are 4:3. I still can't do better than 75 Hz, but
that will have to do until I get a new monitor. When I was buying this one I
made the mistake of concentrating on the highest resolution possible, and
not the frequency of a resolution I'd be likely to use. Actually this
monitor is capable of 80 Hz at 1280 x 1024, but as luck will have it, my new
video card doesn't support that particular frequency.

Thanks for the reply.

 

[Not Gimpy Anymore]

No, it's not a macho thing..... my old eyes definitely prefer 85 Hz, more
if
they can get it.

Actually this flies in the face of Human Factors data that says "eyes
slow
down with age" - FWIW. Maybe there are complicating perceptual factors,
in which case a visit to a capable opthalmologist may be in order to assure
there are no serious medical complications involved.

Interesting that it will support the high refresh at this format, but not
others - then it's really likely to be a "plug-n-play" issue between the
monitor
and video card. Sounds like the monitor .inf file (if there is one) is not
complete enough - or else the video driver is not properly calculating
the monitors capabilities. Depending on your OS & driver, you may be
able to work around that shortcoming, if you want to. Don't be fraid to
play around with the advanced display properties to see what you can
do.

NGA

 

[chrisv]

Read an interesting
thing about cats ( I'm not a cat ) which claimed some cats can't see
anything on a TV screen because they process so fast all they see is a
moving point of light.

Couldn't be. The phosphor itself has some persistence, i.e. it
continues to glow, even after the electron beam has moved on.

 

[Bob Myers]

Couldn't be. The phosphor itself has some persistence, i.e. it
continues to glow, even after the electron beam has moved on.

Actually, not all that much - the persistence of standard color
phosphors is in the low hundreds of microseconds for even the
slowest. (And even that is to 10% of the initial luminance.) To
a fast enough camera, the image on a CRT screen REALLY IS
just a moving spot of light, with a very dim after-image remaining
behind it. (Which is why we perceive flicker, for one thing - the
CRT really is a very highly-varying light source.)

I've also been led to understand that other animals tend not to
perceive TV and other images as we do, but for a different
reason - that they simply can't make the leap from seeing a
2-D image to in some way "believing" that it is a representation
of 3-D reality. On the other hand, I once had a miniature
schnauzer who was absolutely fascinated by television, especially
animal shows - so go figure. I am pretty confident that whatever
the explanation, it doesn't involve other eyes being significant
faster than ours, as the response speed of vision has to do with
some interesting chemical and neural actions going on in the retina
and the visual cortex of the brain, and I doubt that these are all
THAT much different in cat's eyes. I could easily be wrong in this,
though - there are certainly other significant differences between
human vision and that of other animals, including some which have
significantly greater visual acuity ("resolution") than we do, and some
which even use a different set of "primaries" (I have been told there
are, for instance, some insect eyes based on more than three primaries,
and there are certainly many types of eyes that see outside of what
we humans consider to be the "visible" spectrum.)

Bob M.

 

[chrisv]

Actually, not all that much - the persistence of standard color
phosphors is in the low hundreds of microseconds for even the
slowest. (And even that is to 10% of the initial luminance.)

Well, an entire line will be drawn in about 140 microseconds (NTSC) or
10-20 microseconds (computer monitor)...

To a fast enough camera, the image on a CRT screen REALLY IS
just a moving spot of light, with a very dim after-image remaining
behind it.

Seems to me it would have to look (at least) like a moving line,
obviously with decreasing brightness the further from the lead spot.

(Which is why we perceive flicker, for one thing - the
CRT really is a very highly-varying light source.)

Of course.

 

[Bob Myers]

Seems to me it would have to look (at least) like a moving line,
obviously with decreasing brightness the further from the lead spot.

Sort of - it really is a case of the spot where the beam is at
the moment being VERY bright, and the phosphor "trailing"
the spot very rapidly decreasing in brightness. Remember, that
"hundreds of microseconds" number I gave for color phosphor
persistence is for the slowest phosphor. A more complete
description would be a very bright spot, trailing a dimmer
line, trailing a series of much dimmer lines.

Bob M.

 

[Box134]

Actually this flies in the face of Human Factors data that says "eyes
slow
down with age" - FWIW. Maybe there are complicating perceptual factors,
in which case a visit to a capable opthalmologist may be in order to assure
there are no serious medical complications involved.

I had my eyes checked when I got computer glasses and everything was OK.
Best investment I've ever made.

Interesting that it will support the high refresh at this format, but not
others - then it's really likely to be a "plug-n-play" issue between the
monitor
and video card. Sounds like the monitor .inf file (if there is one) is not
complete enough - or else the video driver is not properly calculating
the monitors capabilities. Depending on your OS & driver, you may be
able to work around that shortcoming, if you want to. Don't be fraid to
play around with the advanced display properties to see what you can
do.

I'm not sure why the high refresh occurs at certain resolutions... I think
it may have to do with computational throughput. If card's compute engine is
drawing more lines the scan rate goes down, if it's drawing fewer lines it
can draw them more frequently. Just my non-technical explanation.

I've tried every conceivable variation in advanced properties. If I really
get to despise this monitor I guess I'll have to buy a new one.

 

[Box134]

Of our three cats only one will watch some TV and only when there are birds.
As soon as the bird segment is over he looks away and goes to sleep. The
other two take no notice whatever.

 

[Bob Myers]

I'm not sure why the high refresh occurs at certain resolutions... I think
it may have to do with computational throughput. If card's compute engine is
drawing more lines the scan rate goes down, if it's drawing fewer lines it
can draw them more frequently. Just my non-technical explanation.

No, sorry, it doesn't work that way. The process of refreshing
the screen (i.e., creating the video signals from the content of the
graphics memory) happens completely separate from the process
of creating the images in the first place (which is what the compute
engine does).

IF everything is working properly, then you should be able to
achieve the highest refresh rates with the lowest "resolution"
(the pixel format with the fewest pixels/lines), since the
limits you will run into are (a) how fast pixels can be
clocked out of the graphics memory (by what is, appropriately
enough, called the "pixel clock"), and (b and c) the limits the
monitor will place on the horizontal and vertical scan rates.
However, there may be some artificial (and somewhat
arbitrary and/or seemingly nonsensical) limits imposed by
the drivers or other software.

Bob M.