preserveAlpha

SVG Elements
1. A
2. B-C
3. D
  1. <defs>
  2. <desc>
4. E
  1. <ellipse>
5. F
6. G
7. H
  1. <hkern>
8. I
  1. <image>
9. J-L
  1. <line>
  2. <linearGradient>
10. M
11. N-P
12. Q-R
  1. <radialGradient>
  2. <rect>
13. S
  1. <script>
  2. <set>
  3. <stop>
  4. <style>
  5. <svg>
  6. <switch>
  7. <symbol>
14. T
15. U
  1. <use>
16. V-Z
  1. <view>
  2. <vkern>

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

You can use this attribute with the following SVG elements:

<feConvolveMatrix>

Example

html, body, svg {
  height: 100%;
}

<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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