preserveAlpha

the preserveAlpha attribute indicates how a <feConvolveMatrix> element handled alpha transparency.

You can use this attribute with the following SVG elements:

Example

<svg viewBox="0 0 420 200" xmlns="http://www.w3.org/2000/svg">
  <filter id="convolveMatrix1" x="0" y="0" width="100%" height="100%">
    <feConvolveMatrix kernelMatrix="1 -1 2 0 0 0 0 0 -2" preserveAlpha="true"/>
  </filter>
  <filter id="convolveMatrix2" x="0" y="0" width="100%" height="100%">
    <feConvolveMatrix kernelMatrix="1 -1 2 0 0 0 0 0 -2" preserveAlpha="false"/>
  </filter>

  <image xlink:href="//developer.mozilla.org/files/6457/mdn_logo_only_color.png" width="200" height="200"
      style="filter:url(#convolveMatrix1);"/>
  <image xlink:href="//developer.mozilla.org/files/6457/mdn_logo_only_color.png" width="200" height="200"
      style="filter:url(#convolveMatrix2); transform:translateX(220px);"/>
</svg>

Usage notes

Default value false
Value true | false
Animatable Yes
true

This value indicates that the convolution will only apply to the color channels. In this case, the filter will temporarily unpremultiply the color component values and apply the kernel.

false

This value indicates that the convolution will apply to all channels, including the alpha channel.

Specifications

Specification Status Comment
Filter Effects Module Level 1
The definition of 'preserveAlpha' in that specification.		 Working Draft No change
Scalable Vector Graphics (SVG) 1.1 (Second Edition)
The definition of 'preserveAlpha' in that specification.		 Recommendation Initial definition

Browser compatibility

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/preserveAlpha