21" monitors: quality at low resolutions

Installing the latest version of your graphics card drvier may help.

Erco wrote:
 > I have a 21" CRT trinitron monitor, model SONY GDM-F520, very nice at high
 > resolutions, from 1024x768 to 2048x1536, but when I use low resolutions for
 > playing old games (320x200, 640x480, 800x600) or for DOS text, the quality
 > of the image is very poor, not because the pixels are big (it's logical) or
 > the frequency is low, but because vertical pixels are not adjacent, due to
 > horizontal black lines (like a grille), so vertical lines are discontinuos
 > and not uniform.
 > It's very annoying, the image is not clear (even at 800x600), due to these
 > extraneous horizontal lines.
 > I'd like to know if you experience the same problem.
 >
 > It's a characteristic of every big CRT monitor? Or it's a problem only of
 > the trinitron/aperture grille tube? Shadow mask monitors are better for
 > displaying low resolutions?
 > Before, I had a 15" NEC shadow mask monitor, perfect and clear at every
 > resolution (up to 1024x768)!
 >
 > I supposed that a 21" CRT monitor was the best choice for displaying
 > different resolutions (instead of LCDs that are clear only at the native
 > resolution), but I was wrong (at least with my SONY monitor).
 >
 > What is your experience with low resolutions on 21" monitors?
 > Anyone can give me an explanation of this problem?
 >
 > Thank You!

 >
 >
 >> Stay informed about: 21"" monitors: quality at low resolutions 

On Sat, 5 Jul 2003 02:42:07 +0200, "Erco"
wrote:

 >It's very annoying, the image is not clear (even at 800x600), due to these
 >extraneous horizontal lines.
 >I'd like to know if you experience the same problem.

There should be no problems displaying low resolutions.
 >> Stay informed about: 21"" monitors: quality at low resolutions 

 > There should be no problems displaying low resolutions.

I don't think it's a problem, maybe it's a characteristic of the
Trinitron tube, anyway I don't like how display low resolutions, cause
eye fatigue..
 >> Stay informed about: 21"" monitors: quality at low resolutions 

On 8 Jul 2003 13:14:18 -0700, ercofra.DeleteThis@interoffice.it (Erco) wrote:

  >> There should be no problems displaying low resolutions.
 >
 >I don't think it's a problem, maybe it's a characteristic of the
 >Trinitron tube,

No, it's not. Low resolutions should be extra easy for it to handle.

 >anyway I don't like how display low resolutions, cause
 >eye fatigue..
 >> Stay informed about: 21"" monitors: quality at low resolutions 

"Erco" wrote in message

 > I have a 21" CRT trinitron monitor, model SONY GDM-F520, very nice at high

Large PC monitors have the raster (CRT) gun width optimized for higher
resolutions. I'm not a CRT expert, but I think the beam-spot (when it
strikes the CRT plate) is relatively fixed. Maybe it can 'modulated'
larger/smaller by slight amounts, but not enough to cover the *correct*
sizes for *ALL* resolutions (From 640x480 -> 2048x1536...that's a 4x4
range!)

This means that the raster width will be 'just right' for some res's
(like 1280x1024 and 1600x1200.) It will be 'too large' for other
res's (2048x1536), resulting in overlapping pixels. And finally, for
'legacy' (low) resolutions, the raster will be much too small, leaving
gaps between successive adjacent scanlines.

Not knowing what your monitor looks like, it's hard to say whether
you're observing the 'expected' raster-width or an actual problem with
the CRT. 640x480 on my Viewsonic P225 (21" shadow-mask CRT) is painful
to look at for exactly the reason you describe. (Vertical lines have
'breaks' in them at every scanline.)

And incidentally, in the original IBM VGA monitor specification, all
200/240-line modes were physically 400/480 line-modes. The VGA-CRTC
controller double-scanned each framebuffer-scanline to simulate a
half-vertical resolution on the CRT-display. There were two reasons
for this... building a wide-band monitor (15KHz - 32KHz) was expensive
in those days, and a true 200/240-line mode = ~15.7KHz scanline rate.
The other reason is likely due to the electron-gun's spot-size. Either
the designers could choose for CGA (200-scanline) resolutions, and
have terrible VGA (400/480-scanline) display, or target the other way
around.

 > resolutions, from 1024x768 to 2048x1536, but when I use low resolutions
for
 > playing old games (320x200, 640x480, 800x600) or for DOS text, the quality
 > of the image is very poor, not because the pixels are big (it's logical)
or
 > the frequency is low, but because vertical pixels are not adjacent, due to
 > horizontal black lines (like a grille), so vertical lines are discontinuos
 > and not uniform.
 > It's very annoying, the image is not clear (even at 800x600), due to these
 > extraneous horizontal lines.
 > I'd like to know if you experience the same problem.
 >
 > It's a characteristic of every big CRT monitor? Or it's a problem only of
 > the trinitron/aperture grille tube? Shadow mask monitors are better for
 > displaying low resolutions?
 > Before, I had a 15" NEC shadow mask monitor, perfect and clear at every
 > resolution (up to 1024x768)!
 >
 > I supposed that a 21" CRT monitor was the best choice for displaying
 > different resolutions (instead of LCDs that are clear only at the native
 > resolution), but I was wrong (at least with my SONY monitor).
 >
 > What is your experience with low resolutions on 21" monitors?
 > Anyone can give me an explanation of this problem?
 >
 > Thank You!

 >
 >
 >
 >> Stay informed about: 21"" monitors: quality at low resolutions 

Thank you Lash, you say interestings things, that describe my problem
and give a possible reason.

My monitor is optimized for high resolutions (up to 2048x1536 @ 86 Hz,
0.22mm pitch) and maybe the beam-spot don't cover the correct pixel
size for low resolutions, leaving gaps between successive adjacent
scanlines (it's exactly what I see). The gaps are bigger for very low
resolutions (320x200, 640x480), and, as the resolution increase, the
size of the gaps decrease, until it's indistinguishable from 1280x1024
to 2048x1536.

But, wait, why the gaps are only between adjacent horizontal
lines(causing breaks in vertical lines) and there are no breaks in
horizontal lines?

Another question comes to my mind: a solution for displaying low
resolutions with a little beam-spot, is to double/quadruple-scan each
scanline(like you describe for old VGA monitors), for example I can
simulate 640x480 with a physical resolution of 1920x1440, triplicating
the scanlines (1920=640x3, 1440=480x3); I don't think it's difficult
to implement a controller that do it, maybe, who make big monitors
don't care about the quality at low resolutions because suppose that
who buy a costly 21" CRT monitor he's a professional that never use it
under 1280x1024.

And what about LCDs? I think that big LCDs with a physical resolution
of 1600x1200 can simulate low resolutions better than big CRT
monitors, so in the future, big LCDs with fast response time will be
the perfect choice for professionals and gamers. What you think?
 >> Stay informed about: 21"" monitors: quality at low resolutions 

On 10 Jul 2003 17:31:13 -0700, ercofra.RemoveThis@interoffice.it (Erco) wrote:

 >But, wait, why the gaps are only between adjacent horizontal
 >lines(causing breaks in vertical lines) and there are no breaks in
 >horizontal lines?

I have to correct myself. In my previous post, I wasn't thinking of
the gap between scan lines at low resolutions. Sorry for the
misinformation.

Now, the answer to the above question is simple. The electron beam
draws each horizontal line in a continuous sweep, so there are no
gaps. At the end of each line, it will "jump" down to the next line,
which may indeed be far-enough away so that a gap appears between
successive lines.
 >> Stay informed about: 21"" monitors: quality at low resolutions 

 > At the end of each line, it will "jump" down to the next line,
 > which may indeed be far-enough away so that a gap appears between
 > successive lines.

Ok, we've focused the problem, however my old NEC 15" don't suffer of
this defect, pixels at low resolutions (320x200, even at CGA/EGA) are
of the correct size and cover all the screen uniformly; these
pixels(of the NEC), are big and square, not round, so I suppose that
each line is scanned several times, without gaps.

I'd like to know if every big CRTs have the gap defect, or there are
monitors that use the technique of my old good NEC for simulating low
resolutions.

John Gill, you say that your Mitsubishi monitor is good at 800x600, do
you try 320x200 or 640x480? Don't you see gaps between successive
lines?
 >> Stay informed about: 21"" monitors: quality at low resolutions