Patents in PS3 (Was: Re: [pdftex] xpdf (was: [Gs-devel] Re: [gnu@to ad.com: Re: EFF place holder...

[luke.kendall at cisra.canon.com.au]

On 10 Feb, Raph Levien wrote:
>  Lastly, there is the spectre of the Schreiber patent on color 
>  management. The exact scope of validity of this patent is a subject 
>  of intense controversy. The current assignee (EFI) has pursued it 
>  very aggressively, and has apparently collected a lot of money in 
>  settlements. It's also a matter of some debate whether PostScript 
>  LL3 really does "color management" - in the graphic arts market, 
>  native PostScript "color rendering dictionaries" have been all but 
>  abandoned in favor of ICC. 

My understanding is that Adobe have come up with a good implementation
of using Coons patches for color blending (arguably the obvious
implementation, but anyway ...).

PS level 3 provides blend objects, (maybe even as Coons patches?), as
objects for the user to work with.  So if you don't have a way of
implementing them, then you don't have a full clone.  You'll need to
take care to avoid their patent.  It might be enough to avoid the
method they use to determining whether a sub-division is small enough
to be drawn with a flat colour.

http://www.trilithon.com/pagesous/shading.html has a writeup on blending
in PS3, which you probably all know about anyway.

Some US patents that are relevant, most relevant first.  There are
others that I have heard of.

US 6,313,840 "Smooth shading of objects on display devices"
US 6,147,689 "Displaying 2D patches with foldover"
US 6,271,861 "Smooth shading of an object" (more for interactive work,
I think).

You might need to search the European Patent database, to find other
patents they may have.  http://gb.espacenet.com/

Possibly irrelevant patents I turned up on the European site while
trying to dig up the above ones:

http://l2.espacenet.com/dips/viewer?PN=EP1111542&CY=gb&LG=en&DB=EPD
http://l2.espacenet.com/dips/viewer?PN=EP0924651&CY=gb&LG=en&DB=EPD

luke