It seems most people are not checking out the site (my guess, since everyone
is describing what's usually done to achieve sub pixel rendering), as the
technique described on www.grc.com really shows its full effect only on
LCD's. It does also have the side-effect of creating anti-aliased edges, but
that is not the main point.

Adrian

> -----Original Message-----
> From: Henrik Gedenryd [mailto:Henrik.Gedenryd at lucs.lu.se]
> Sent: October 6, 1999 11:41 AM
> To: Squeak list
> Subject: ClearType for Squeak/Sub-pixel antialiasing
> 
> 
> The TrueType font rendering and antialiasing in Squeak is 
> very cool. I 
> realized it would be quite easy to implement sub-pixel 
> rendering, at least
> in a simple form.
> 
> If you haven't heard of it, sub-pixel rendering is when you 
> manipulate the
> individual R, G and B cells of an LCD screen's pixels to achieve a 3x
> increase in horizontal antialiasing resolution, which makes 
> especially text
> much sharper. In effect, you use the three cells of each pixel as
> independent pixels, and balance their colors so you don't 
> notice that they
> are of different colors (like you don't notice that a white 
> pixel is made of
> one red, one green, and one blue cell).
> 
> Now this only works on LCD screens (more or less), but that's what a
> Dynabook is meant to use after all, isn't it?!! Or you could use that
> 22-inch Apple $4000 monster LCD monitor, for example...
> 
> Microsoft is implementing this as ClearType, boasting about 
> it and claiming
> to have invented it, although it's an old invention by Apple, 
> Xerox, and
> others (hmm, doesn't that sound familiar?).
> 
> A good description of how it works and of how to implement 
> it, with good
> pictures and a simple demo implementation, is at
> http://www.grc.com/ctwhat.htm
> (Those three pages are all the information I needed to do my 
> preliminary
> implementation, in my spare time. It ended up being only 
> 20-30 lines of
> Squeak.)
> 
> I attached a small sample GIF as an illustration. In it, the 
> four variants
> are, top to bottom:
> 
> 1. Standard Morphic anti-aliasing
> 2. Simple sub-pixel version without color balancing (notice color
> artifacts).
> 3. 3-pixel color balancing.
> 4. 5-pixel color balancing. Should be sharper than #3 but 
> appears not to be;
> I don't know why.
> 
> Note that the vertical resolution is not improved by this technique.
> 
> However, Andreas Raab tells me, "the reason that none of the TrueType
> stuff is actually used is that we don't have grid-fitting or 
> hinting in
> Squeak which means that despite the efforts of anti-aliasing 
> stuff fonts at
> small resolutions are hardly readable (too blurry)". Now sub-pixel
> techniques improve this a lot (as the right sample in the 
> image is meant to
> show; the effect is even greater with italics).
> 
> The lack of grid-fitting is the cause, I believe, of the gray 
> blur that can
> be seen in particular inside the lower case 'e', and below 
> the horizontal
> bar of the 'A', in the small samples.
> 
> Actually, also the SP-rendered images would become even sharper with
> improved type rendering, as they use the same anti-aliasing code.
> 
> Are these improvements hard to do? I'm not sure, does anyone 
> out there know?
> There is eg. a free-source (C) package called FreeType that implements
> TrueType rendering with hinting and all. Now I'm just hoping 
> that others
> also would like better TrueType support in Squeak, and would 
> like to chip in
> w r t hinting etc. and implementing general use of outline 
> type in Squeak.
> 
> Note that we have a working cross-platform version of 
> ClearType even before
> Microsoft has released any version at all! As for now, this is just an
> experimental implementation. It can be made more general, 
> much faster, and
> better integrated into Morphic, for example.
> I am on my part certainly willing to do the fixes needed to 
> make it general
> enough, and to optimize it and produce a C-compiled version 
> for Balloon.
> 
> Anyone?
> 
> Henrik
> 
> < = > .
> 
>