[wp-trac] [WordPress Trac] #63448: Image quality significantly degrades for resized PNGs with transparency in WordPress 6.8.1

[WordPress Trac]

#63448: Image quality significantly degrades for resized PNGs with transparency in
WordPress 6.8.1
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 Reporter:  elvismdev                            |       Owner:
                                                 |  adamsilverstein
     Type:  defect (bug)                         |      Status:  reopened
 Priority:  normal                               |   Milestone:  6.8.2
Component:  Media                                |     Version:  6.8
 Severity:  critical                             |  Resolution:
 Keywords:  has-patch has-test-info dev-         |     Focuses:
  feedback has-unit-tests commit fixed-major     |
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Comment (by SirLouen):

 Replying to [comment:73 adamsilverstein]:
 > Here is the relevant bit of code that we had in place previously:
 >
 >
 > {{{
 > // Reduce colors in the images to maximum needed, using the global
 colorspace.
 > $max_colors = pow( 2, $indexed_pixel_depth );
 > if ( is_callable( array( $this->image, 'getImageColors' ) ) ) {
 >     $current_colors = $this->image->getImageColors();
 >     $max_colors     = min( $max_colors, $current_colors );
 > }
 > $this->image->quantizeImage( $max_colors, $this->image->getColorspace(),
 0, false, false );
 > /**
 >  * If the colorspace is 'gray', use the png8 format to ensure it stays
 indexed.
 >  */
 > if ( Imagick::COLORSPACE_GRAY === $this->image->getImageColorspace() ) {
 >     $this->image->setOption( 'png:format', 'png8' );
 > }
 > }}}

 And for the icing, we had to add this report #63481

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Ticket URL: <https://core.trac.wordpress.org/ticket/63448#comment:74>
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