Beta test Bitstream Vera fonts available.

Jim.Gettys at hp.com Jim.Gettys at hp.com
Wed Feb 26 04:15:20 UTC 2003



> Sender: squeak-dev-bounces at lists.squeakfoundation.org
> From: "Andreas Raab" <andreas.raab at gmx.de>
> Date: Tue, 25 Feb 2003 23:15:48 +0100
> To: "'The general-purpose Squeak developers list'"
> <squeak-dev at lists.squeakfoundation.org>
> Subject: RE: Beta test Bitstream Vera fonts available.
> -----
> Thanks. I've tried them out but the quality in small sizes is not overly
> convincing. I've attached a small picture that shows Vera Sans in different
> sizes (VeraSansStrike.gif). Since the glyphs were generated using Squeak (w/
> font plugin) I cannot judge the kerning (Squeak doesn't use the kerning
> pairs currently) but some of glyphs look problematic - for example, watch
> the "O" in line 1 and 3, the "b" in Line 2, the "ö" (o-umlaut) and question
> marks in line 4 the "N" in lines 5 and 6. The other fonts included look
> similar in quality; generally good fonts but somewhat poor at small sizes.
>
> I've also tried with Yoshiki's TTF support and it looks better, yet at small
> sizes it is too washed out (see VeraSansTTF.gif). So it seems that while
> these fonts are nice they aren't really as great in small sizes.
>
> BTW, someone wrote that these fonts are hinted - is this certain?! From the
> looks of it I see nothing that seems to go beyound regular drop-out support
> but maybe Windows (aka: the font plugin) is screwing me. I'd like to see if
> someone on a different platform can get "better results" than what I am
> seeing.

There are no delta hints in Vera: they will not generate good bitmaps at
small sizes.  They are intended for use primarily anti-aliased as we
now do on Linux; antialiased, they do very well indeed at small sizes.
Prima, from which Vera was derived, did have delta hints,
but due to the procedure used to generate them, had bad results when
imaged anti-aliased (alot of strokes went to zero width).
(Bitstream has since changed how they generate
their delta hints).  But Vera is otherwise nicely hinted...

I use Vera very nicely on my iPAQ handheld at 6 pixels size :-)....

For some samples of where things are at using all open source technology,
see: http://zap.crl.dec.com/Screenshot-4.png and http://zap.crl.dec.com/Screenshot3.png.  This is best looked at on
a flat panel with typical horizontal rgb subpixel order.  Most things
on those two shots are in one face of Vera or another....

One is of my desktop (yes, I do have MS Office installed on my Linux machine);
the other is primarily a waterfall display app of one of the fonts.

There will be some additional work done on hinting over the next few weeks.
You can see in the waterfall display a few characters need some additional
TLC, as also you observed...

Here's the scoop:

Xft2 use Freetype for the basic rasterization; but that is just the start.
Xft2 adjusts the hinting to keep things on pixel boundaries much more than
Microsoft Cleartype does (which appears to at most adjust to subpixel
bounadaries); we believe this is better, and I think the
above shot of my desktop bears this out.  The resulting glyphs are imaged
at 3 times the horizontal or vertical resolution (depending on flatpanel
subpixel order and orientation), and the results used to form a glyph which
is alpha composited to the screen.  This process Keith Packard calls subpixel
decimation.  So we end up a bit less faithful to the font outlines, but
less fuzzy than Cleartype (which is sharper than not doing subpixel stuff
is in the first place).

Xft2 will either use the X render extension for the alpha compositing,
or will go down to pixels, alpha composite them to pixels extracted
from the screen, and shove the pixels back to the screen if render isn't
present.  All the code is open source (MIT  license).
                                     - Jim

--
Jim Gettys
Cambridge Research Laboratory
HP Labs, Hewlett-Packard Company
Jim.Gettys at hp.com



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