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

Re: Compositing math in SVG

From: Rik Cabanier <cabanier@gmail.com>
Date: Wed, 11 Jul 2012 12:06:33 -0700
Message-ID: <CAGN7qDDf9OXWpkq==2B5K5G+SYEn5ZPKf5WCbtrj8dfRMacVPw@mail.gmail.com>
To: Calculemus <calculemus1988@gmail.com>
Cc: www-svg@w3.org
On Wed, Jul 11, 2012 at 8:39 AM, Calculemus <calculemus1988@gmail.com>wrote:

> Another blend mode with different math, pin light:
> http://illusions.hu/effectwiki/doku.php?id=pin_light_blending
> http://www.imagemagick.org/Usage/compose/#pinlight
> I drew decision trees and checked for which conditions
> which results you get, and those are indeed different.

It's unfortunate that different implementations exist. However, as long as
they don't export to HTML and expect it to blend the same, there should be
no issue.

> There are many blend modes that svg does not have from
> these sources:
> www.imagemagick.org./Usage/compose
> www.pegtop.net/delphi/articles/blendmodes/
> and others.

I'm sure that there are many more blending modes. Photoshop has a bunch
that we didn't include either.
The SVG blending spec aimed to implement the PDF blend modes so we stuck
with that.

I was hoping that we could extend blending with GPU shaders which would
allow any operation. However, because the security issues we've seen with
filter effects, it is not an option at this point.
Once the GPU drivers are better, we can revisit the issue.

> I am trying to construct a maximal set of blend modes
> and to confirm the math for all of them. I will later combine
> those with Porter-Duff compositing operations.
> I can help you enrich svg but will need your help on things
> like this for this journey ;)

 Thanks! Don't forget that this feature applies to HTML as well!
Received on Wednesday, 11 July 2012 19:07:01 UTC

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