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

Re: Compositing math in SVG

From: Rik Cabanier <cabanier@gmail.com>
Date: Tue, 10 Jul 2012 09:15:52 -0700
Message-ID: <CAGN7qDAYHhAfqceY-jKACw_EqGxhj9WuE21YkHY=Mb=YLHawMQ@mail.gmail.com>
To: Calculemus <calculemus1988@gmail.com>
Cc: www-svg@w3.org
Good catch!

As long as the math is done in floating point, there should be no
difference since the formulas become the same around .5.
However, if you do the math in bytes there will be some slight differences.
This would be an implementation issue and not something for the blending
spec where we're always talking about floats.

Rik

On Tue, Jul 10, 2012 at 2:08 AM, Calculemus <calculemus1988@gmail.com>wrote:

> "Let me know if you think that there are blend modes that are not in the
> current spec but that you believe should be included. I noticed that gimp
> has a bunch that are not in our current spec."
>
> Sure, I will be doing extensive study for this, since we want bullet-proof
> software.
>
> Here is another confusing thing. In some places the condition for
> hard-light is different.
>
> Places where the condition for hard-light is "if (top < 0.5)":
>
> 1. http://www.pegtop.net/delphi/articles/blendmodes/hardlight.htm
> 2. http://yahvuu.wordpress.com/2009/09/27/blendmodes1/#blend_basics
> 3.
> http://msdn.microsoft.com/en-us/library/windows/desktop/hh706313%28v=vs.85%29.aspx
>
> Places where the condition for hard-light is "if (top <= 0.5)":
>
> 1. http://dvcs.w3.org/hg/FXTF/rawfile/tip/compositing/index.html#blending
> 2. The Adobe reference 1.7
>
> Opinion on this? Does it matter?
>
Received on Tuesday, 10 July 2012 16:16:20 GMT

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