> But a high resolution device with good dithering algorithms should be
> able to overcome the problem. Display dithering on analogue monitors
> has been around since the early 80's so the technology should be well
> understood.
Dithering is for a lack of colour depth, not a lack of resolution, and
I think would give an even more offputting effect than the current one.
Currently, if I want to display (say) the letter "I" on a 3:2 upscaled
LCD screen, assuming the original image is (fixed-point font, please):
XXX
X
X
X
XXX
then I'll either get:
XXXXX
X
X
X
XXXXX
or
XXXX
XX
XX
XX
XXXX
depending on if the center pixel is on a 1 or a 2-upscale boundary.
With dithering, I'd get
XXXX
X X
XX
XX
XXXX
or something equally painful, depending on how it decided to spread
out the pixels.
Now, you could get the desired effect with temporal dithering, but
that's more commonly known as flickering.
The "cleartype" that some people have mentioned is based on the fact
that most LCD screens are arranged with the pixels something like:
RGB RGB RGB RGB
RGB RGB RGB RGB
RGB RGB RGB RGB
so if you want to display a one-and-two-thirds pixel wide line, you can do
..B RGB R...
..B RGB R...
..B RGB R...
It sounds weird, but it actually works pretty well -- but only for
black-on-white text. It doesn't work that well for white-on-black text,
the coloured halos are more noticeable and it really doesn't work at all
for general coloured images, for obvious reasons. And, in practise, it's
used for text rather than general antialiasing, because there's
information available for subpixel-resolution rendering of text, so they
can do useful things. It also only works in the horizontal dimension
(for most LCD screens -- there may be ones which arrange the subpixels
vertically, I don't know for sure).
Now, all of this stuff starts to get much more complicated when you
get into the world of HDTV and the various up/downscalers there -- but
one of the reasons that HD-DVD players hundreds of dollars more than
normal ones is that they have very sophisticated stuff in there to do
live _nice_ upscaling of lower-resolution images to HDTV screens.
-- dan
-- dan
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