Re: [fxtf-drafts] Clarify the size of the "input image" (#324)

@mstange The spec text says:

> Determines how to extend the input image as necessary with color values so that the matrix operations can be applied when the kernel is positioned at or near the edge of the input image.

"input image", across the spec, specifies the input into the filter primitive. For chained filter primitives the size of the input image depends on the filter primitive region of the previous filter. Here, the input is the `SourceGraphic`. So the input image size depends on the image size of the `SourceGraphic`. In your example, the input image has a size of 20x20 and _not_ 100x100.

The [filter region]( is a clipping region that:
1. Determines the final paint size
2. Clips all input filter primitive subregions.

So while the filter region in your example should not have any affect. In the following it would:

<svg xmlns="" width="500" height="500">
  <filter id="f1" filterUnits="userSpaceOnUse" x="10" y="10" width="100" height="100">
    <feGaussianBlur stdDeviation="10" edgeMode="duplicate"/>
  <g filter="url(#f1)">
    <rect x="0" y="0" width="20" height="20"/>

Here the input gets clipped to the filter region and has the size of 10x10 now.

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Received on Monday, 16 September 2019 01:20:34 UTC