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Re: [filters] what should feGaussianBlur sample outside the source image?

From: Nikos Andronikos <nikos.andronikos@cisra.canon.com.au>
Date: Tue, 7 Aug 2012 13:09:27 +1000
Message-ID: <502086E7.7010600@cisra.canon.com.au>
To: <public-fx@w3.org>
Hi Dirk,

In the definition for FillPaint, what does the following line mean?

This keyword represents the target element rendered filled.

What I would read it to mean conflicts with my previous understanding of FillPaint, and the other text in the definition.

On 7/08/2012 11:50 AM, Dirk Schulze wrote:

It clarifies already that requested pixels outside of the current primitive are assumed to be transparent black. Therefore the rendering output of opera and webkit is correct here. FillPaint is a pseudo filter primitive and does not contribute to the context you describe. I can add the quotes in a follow up mail once I am on my desk if you can't find the necessary quotes.

Greetings
Dirk

Sent from my iPhone

On Aug 6, 2012, at 5:28 PM, "Cameron McCormack" <cam@mcc.id.au><mailto:cam@mcc.id.au> wrote:



Consider this document:

  http://people.mozilla.org/~cmccormack/tests/blur.svg

The Filters spec (and SVG before it) says the following in the
feGaussianBlur section:

  If the input has infinite extent and is constant (e.g FillPaint,
  this operation has no effect.

The document uses FillPaint as the input to feGaussianBlur, but in Opera
at least, the blue rectangular area has blurry edges, because it is
(presumably) sampling transparent black outside the source image area.
For the operation to have no effect, you would expect the rectangle to
have sharp edges, which would imply sampling the FillPaint outside the
source image area.

The test
http://dev.w3.org/SVG/profiles/1.1F2/test/harness/htmlObjectMiniApproved/filters-overview-01-b.html
seems to assume that transparent black is sampled outside the source
image area.

The spec should be clarified to indicate how to sample around the edges
of the source image, and if it should be transparent black, the sentence
about having no effect with FillPaint should be changed.






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Received on Tuesday, 7 August 2012 03:09:57 GMT

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