[wp-trac] [WordPress Trac] #39216: PDFs with non-opaque alpha channels can result in previews with black backgrounds.

[WordPress Trac]

#39216: PDFs with non-opaque alpha channels can result in previews with black
backgrounds.
-------------------------------------------------+-------------------------
 Reporter:  gitlost                              |       Owner:  (none)
     Type:  defect (bug)                         |      Status:  new
 Priority:  normal                               |   Milestone:  Awaiting
                                                 |  Review
Component:  Media                                |     Version:  4.7
 Severity:  normal                               |  Resolution:
 Keywords:  dev-feedback 2nd-opinion has-patch   |     Focuses:
  has-unit-tests                                 |
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Comment (by 6adminit):

 Replying to [comment:8 emirpprime]:
 > We've just upgraded ~20 servers to Debian 9 from Deb7/8 and been bitten
 by this. Unfortunately in all the testing no-one happened to upload a PDF
 with transparency in it.
 >
 > So far, modifying the {{{decode="ps:alpha}}} line in
 {{{/etc/ImageMagick-6/delegates.xml}}} from {{{-sDEVICE=pngalpha}}} to
 {{{-sDEVICE=jpeg}}} has fixed it.
 >
 > ----

 I can confirm this very simple mod do the trick for us too

 Configuration:
 Debian 10
 PHP 7.2.27
 Ghostscript 9.27

 Command:

 {{{
 sed -i.back -e 's#pngalpha#jpeg#g' /etc/ImageMagick-6/delegates.xml
 }}}

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Ticket URL: <https://core.trac.wordpress.org/ticket/39216#comment:14>
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