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- To: mjd@MATH.AMS.ORG, email@example.com
- Subject: Re: Thoughts
- From: "Y&Y, Inc." <support@YandY.com>
- Date: Mon, 16 Feb 1998 13:00:11 -0500
At 09:17 AM 98/02/16 -0500, Michael John Downes wrote:
>I'm not exactly an expert in PS rendering, could someone explain how a
>hinted bar is going to be rendered better than a lineto at low
>resolutions? I don't see how there could be a significant difference
>unless the PDF viewer is really brain-dead about rendering horizontal
>and vertical lines. Doesn't it boil down in practice to choosing between
>one-pixel thickness or two-pixel thickness, and shifting 0.5 pixel (or
>less) in a vertical or horizontal direction to put the line on a pixel
>boundary? Are you saying that Acrobat Reader *doesn't* do a good job of
>this for plain old horizontal and vertical lines, but somehow can do
>better with bar glyphs from a font?
I guess you haven't seen PDF output made from DVIPS PS files :-)?
Acrobat Reader *can* do a good job of rendering rules, but only
if you draw them in a way that it can understand they are supposed
to be rules. (For a start, PS from DVIPS `snaps to'
the `underlying' grid - which of course in the case of Distiller is a
meaningless 144 dpi).
In any case, the hinting in a font may cause parts of glyphs to move
which will make things not line up with a line drawn some other
way. This generally means that it is more reliable to use glyphs
when constructing some larger entity rather than rules mixed
with glyphs. At high resolution, of course, it doesn't matter. And at
very low resolution you can get artifacts even when all parts come
from a font (because the character level hinting will distort the
coordinate system in different ways in different chaacters).