Text looks kind of fuzzy in portrait mode

Whenever I use my monitor in portrait mode, all text looks, well, exactly like the way Safari 3 for Windows renders text. For those who haven't used Windows Safari 3, here's a description: essentially, what I mean is that everything looks a little fuzzy and bolded/shadowy.

I can't figure out if this is because of the monitor (I expect better from IPS panels), the GPU (tried both AMD and Nvidia graphics cards), the OS (Cleartype is enabled already, so I don't know what else to try), or if it's just a placebo effect. Any ideas?

 

What's the LCD's native resolution, and what is it when it's in portrait?

 

The LCD's native resolution is 1680x1050, and in portrait mode the resolution is 1050x1680.

One more thing I forgot to mention earlier: The monitor is connected to my computer via DVI.

 

well, cleartype only really works well as long as the pixel have vertical color bars. when you turn the screen, they get turned and are horizontal, then, which doesn't work really with cleartype. you lose 3x the horizontal resolution (the resolution, that matters most for font rendering) => it gets more blurry.

 

I think windows 7 support horizontal cleartype.

 

it's unimportant what the os supports: the SCREEN doesn't support horizontal cleartype. text is mostly vertical tilted (see the y, see the A, etc.. most are nearly vertical lines). to increase the crispness and smoothness of those near-vertical lines, you have to increase the resolution horizontally. and to do so, pixels have to be layed out like this:

R G B
R G B
R G B


one pixel, 3 vertical suppixels.

but if you turn the screen, it won't be like that anymore, it will be like this:

RRR
GGG
BBB

and your horizontal increase in resolution is gone. and there, your crispness of cleartype.

this will only change if we get one day pixels similar to digicams layouts:

R G
G B

it would reduce the horizontal res, but increase the vertical one.