[wp-trac] [WordPress Trac] #48842: Fix calculation error when resampling images before resizing in class-wp-image-editor-imagick.php

[WordPress Trac]

#48842: Fix calculation error when resampling images before resizing in class-wp-
image-editor-imagick.php
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 Reporter:  azaozz                               |       Owner:  (none)
     Type:  defect (bug)                         |      Status:  new
 Priority:  high                                 |   Milestone:  5.3.1
Component:  Media                                |     Version:  4.5
 Severity:  normal                               |  Resolution:
 Keywords:  has-patch 2nd-opinion needs-testing  |     Focuses:
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Comment (by vanyukov):

 @azaozz , the "to be more efficient" was for resource handling. When
 debugging the issue with large sizes not being generated, I went back to a
 4 or 5 years back discussion in trac and there was a reference to this
 article:
 https://www.smashingmagazine.com/2015/06/efficient-image-resizing-with-
 imagemagick/

 I can see that many image optimization settings are similar in WordPress,
 so I assumed a lot was taken from that article. Here's a quote:

 >This means that if we were resizing an image to be 500 pixels wide,
 -thumbnail would first resize it to 2,500 pixels wide using -sample; the
 result might be blocky and pixelated, as we saw in the examples above, but
 the operation would be fast and would produce a result with a small file
 size. Then, ImageMagick would resize this image from 2,500 pixels wide to
 500 pixels wide using -resize. This smooths out the blockiness, but the
 file size stays pretty low.

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Ticket URL: <https://core.trac.wordpress.org/ticket/48842#comment:5>
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