At 8:47 AM -0800 2/26/03, <Jim.Gettys at hp.com> wrote:
>Fine as far as I can tell.  On plain old CRT's, you skip the
>subpixel stuff, of course, and CRT's add "natural" fuzz whether you like
>it or not.

But OTOH you *do* get better Nyquist filtering along the horizontal 
with something close to the right lowpass filter at the sampling 
limit. The lack of this in any dimension on flat panels is one of the 
big reasons why the pitch has to be so high on flat panel displays.

BTW, Color picking on CRTs for better antialiasing has been 
successfully used in the past by various folks and groups including 
the old Negroponte Architecture Machine Group at MIT. (So it can be 
done.)

Cheers,

Alan

At 8:47 AM -0800 2/26/03, <Jim.Gettys at hp.com> wrote:
>  > Sender: squeak-dev-bounces at lists.squeakfoundation.org
>>  From: "Andreas Raab" <andreas.raab at gmx.de>
>>  Date: Wed, 26 Feb 2003 10:20:49 +0100
>>  To: "'The general-purpose Squeak developers list'"
>>  <squeak-dev at lists.squeakfoundation.org>
>>  Subject: RE: Beta test Bitstream Vera fonts available.
>>  -----
>>  Hi Jim,
>>
>>  > 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.
>>
>>  Yup, that's what I thought.
>>
>>  > 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....
>>
>>  Looks very impressive. In particular the small fonts look not washed out at
>>  all and appear very readable at small sizes.
>>
>>  > 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...
>>
>>  *Grin* Compared to what I sent these look _perfect_ ;-)
>
>Glad you think so.  For the record, note that I have the TrueType hinter
>enabled on my machine in Freetype; dunno how you have it set.
>
>The latest freetype's autohinter (used if TrueType possibly
>patented algorithms are not enabled) continues to improve btw.... 
>What you get out of the box on Linux depends on the Linux
>distribution you use.
>
>>
>>  > 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.
>>
>>  Absolutely agree. The quality is amazing. So Xft2 hacks the hinting?! Sounds
>>  somewhat scary ;-)
>>
>
>Yes, Keith Packard can be a bit scary at times... :-)  There is also one
>additional idea that could be tried; rather than keeping the character's
>strokes on pixel boundaries, keep a triad of subpixels together; that
>might allow better positioning of the glyphs on the line, but then the
>green subpixel would not necessarily be at the center (your eye is most
>sensitive to green).  Dunno if Keith will ever try that one out.  This
>all interacts in mystic ways with the human brain's signal processing
>system. Neurons are not the same as a DSP, and the only thing to do
>is to implement and see if you like it better.  The human system
>has *really* sensitive edge detectors...  And flat panels allow
>you to get *MUCH* sharper edges; exploiting that is a major feature...
>
>Basically, you only get AA on pixels that would otherwise have
>ended up involved in jaggies...
>
>>  > 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).
>>
>>  How's the quality for non-LCD screens?! Plain old CRTs for example?
>>
>
>Fine as far as I can tell.  On plain old CRT's, you skip the
>subpixel stuff, of course, and CRT's add "natural" fuzz whether you like
>it or not.
>                            - Jim
>
>
>
>--
>Jim Gettys
>Cambridge Research Laboratory
>HP Labs, Hewlett-Packard Company
>Jim.Gettys at hp.com


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