Sure. There are a number of patents, held/applied for by Microsoft, covering various aspects of sub-pixel rendering of text/images. Here is an example, though a search engine will discover more...
http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=WO0021068&F=0
Some argue that these patents are un-enforcable due to prior art. See http://www.grc.com/ctwho.htm for an overview.
Microsoft indicates that it will license their implementation of sub-pixel antialiasing (a.k.a. ClearType ) for between one and three US Dollars per device. See here for more details...
http://www.microsoft.com/mscorp/ip/tech/cleartype.asp
Apple hold patents for portions of the TrueType hinting mechanisms. The Freetype library source code is distributed in such a manner that it may be compiled with or without the patent restricted code. When compiled without, a patent-free auto-hinting mechanism is employed, which is not as good as the patented code, but far better than nothing. For more information, see...
http://www.freetype.org/patents.html
So, it seems acceptable to distribute patent restricted stuff in source form, and let the user decide what they compile/install/use. The new BitBlt mode does not use any patented code. And so a VM with Freetype plugin/library compiled to use the non-patented auto-hinter, and the modified BitBlt, will be patent free. The sub-pixel stuff, entirely in Smalltalk, and distributed as source, would then be an optional install.
But, of course, I'm not a lawyer :) Cheers, Andy
----- Original Message ----- From: "stéphane ducasse" ducasse@iam.unibe.ch Newsgroups: gmane.comp.lang.smalltalk.squeak.general Sent: Thursday, March 30, 2006 9:11 AM Subject: Re: Henrik antialising
Hi andy
could you explain a bit more the issues with the patents and the license?
Stef On 29 mars 06, at 16:55, Andrew Tween wrote:
I'll see if I can package up a modified Windows VM with Freetype plugin, the new BitBlt mode for sub-pixel, and a semi-stable 3.8Full image. That way, at least the people with Windows can have a play. I think I need to remove the sub-pixel code from the image and make it a changeset, due to the patent issue. I also need to double check that when I built the freetype lib, I didn't compile it with the patented truetype hinting enabled. Patents, don't you just love 'em :)
Does anybody know if it would be ok to put this stuff on ftp.squeak.org ?
Cheers, Andy
----- Original Message ----- From: "Lord ZealoN" lordzealon@gmail.com Newsgroups: gmane.comp.lang.smalltalk.squeak.general Sent: Wednesday, March 29, 2006 3:16 PM Subject: Re: Henrik antialising
I can have this in 3.8?
2006/3/29, Diego Gomez Deck DiegoGomezDeck@consultar.com:
Great!
I can't wait to get a version running on my Squeak.
Cheers,
-- Diego
Here is a screenshot similar to the one Bert posted, but this time with sub-pixel anti-aliasing applied. This will only look o.k. on an LCD monitor with vertical striping in RGB
order.
Cheers, Andy
----- Original Message ----- From: "Diego Gomez Deck" DiegoGomezDeck@consultar.com Newsgroups: gmane.comp.lang.smalltalk.squeak.general Sent: Thursday, March 23, 2006 1:11 PM Subject: Re: Henrik antialising
Hi Andrew,
I've now got everything installed (in a 3.8 image), and the Vera fonts
are
rendering correctly. It looks very good.
Please send the mandatory screenshot.
Cheers,
-- Diego
--
::Mi blog:: http://blog.lordzealon.com