From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <5eb33c612e76a028607ef83642fef691@vitanuova.com>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] writing code
Date: Fri, 18 Feb 2005 20:42:25 +0000
From: rog@vitanuova.com
In-Reply-To: <105ad9921fee22aab9e7df5e0b9fe0f6@terzarima.net>
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> it's really transparency (or opacity), not partial filling (of an area)=
.
> the whole area is filled, but with something more or less transparent/o=
paque.

from the porter-duff paper:
: If =CE=B1(a) and =CE=B1(b) represent subpixel areas covered by opaque g=
eometric
: objects, the overlap of objects within the pixel is quite arbitrary.
: We know that object A divides the pixel into two subpixel areas of
: ratio =CE=B1(a):1-=CE=B1(a).  We know that object B divides the pixel i=
nto two
: subpixel areas of ratio =CE=B1(b):=CE=B1(1-b).  The result of the assum=
ption is
: the same arithmetic as with semi-transparent objects and is summarised
: in the following table: