W3C home > Mailing lists > Public > www-svg@w3.org > December 2013

Re: [filter-effects] Blending without compositing

From: Rik Cabanier <cabanier@gmail.com>
Date: Fri, 6 Dec 2013 09:28:12 -0800
Message-ID: <CAGN7qDCUT7Vvm+jZFS+K3J4NRV6ObSpGB2afWyeXHJ+c3pU3iA@mail.gmail.com>
To: Dirk Schulze <dschulze@adobe.com>
Cc: "public-fx@w3.org" <public-fx@w3.org>, www-svg <www-svg@w3.org>
On Fri, Dec 6, 2013 at 5:16 AM, Dirk Schulze <dschulze@adobe.com> wrote:

> Hi,
>
> The SVG WG resolved at the F2F in Tokyo this summer that <feBlend> in
> Filter Effects should support blending without compositing. This shall
> avoid double compositing as it can happen in combination with
> BackgroundImage today. [1]
>
> We did have some difficulties to define the exact way to disable
> compositing. There are two different proposal so far:
>
> 1) Support all compositing operators on <feBlend>
>
> The idea is that we actually do not disable compositing but allow the
> author to use a different compositing operator. The ‘mode’ attribute could
> be extended to support compositing modes as well:
>
> <blending> = [normal | multiply | screen | darken | lighten] || [over | in
> | out | atop | xor]
>
> which could look like this:
>
> <feBlend mode=“screen atop” in2=“BackgroundImage” />
>

Unfortunately, this does not solve the problem. We want to option to skip
the compositing step, not to replace it with another one.


>
> (The compositing values could be replaced by the keywords used by Canvas.)
>
> 2) Create new attribute ‘compositing'
>
> SVG does not support boolean attributes yet. Therefore the attribute
> ‘compositing' would need values like ‘composite’/’no-compositing’ or simply
> ‘true’/‘false’.
>
> With this attribute the compositing step can just be omitted completely or
> switched to source-over compositing following the formulas from CSS
> Compositing and Blending.
>
>
> Any preferences?
>

I think only option 2 is viable.


>
> [1] http://dev.w3.org/fxtf/filters/#issue-9d31c6c7
>
Received on Friday, 6 December 2013 17:28:42 UTC

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