W3C home > Mailing lists > Public > www-svg@w3.org > August 2012

SVG Compositing

From: Bob Holmes <rangsynth@gmail.com>
Date: Sun, 5 Aug 2012 11:46:52 +0200
Message-ID: <CAMvo67YWoNtns3JFRpHUCDF4871zOU1=-V0HuBnrrL05uc=EVQ@mail.gmail.com>
To: www-svg@w3.org
There is an SVG document called "Compositing and Blending 1.0" dated
"25 July 2012" somewhere around and it splits the compositing and the
blending into two steps. That made for sense to me but now in the
other SVG spec with the "comp op" properties it puts the blenders and
the compositors into the single property, so therefore the result of a
multplication or overlay is not then subject to any further
compositing operator.

Basically for each operator there is the confusion...

1) Does source require premultiplication for all operators...

2) Is the output result color considered as premultiplied or not
premultiplied for all operators. Are some one way and others the

3) Is the input destination or backdrop color premultiplied? This is
what confuses me. In some places it says the output or result color is
premultiplied  but the formulae then goes ahead and acts as if it was
not premultiplied in some cases.

In short, a lot of confusing or seemingly contradicting statements
about what is and is not premultiplied and also if any of the blend
modes actually need to be further composited which seems to make more
sense but not doable with the singular comp op.
Received on Sunday, 5 August 2012 21:22:52 UTC

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