[wp-trac] [WordPress Trac] #55443: Create WebP sub-sizes and use for output

[WordPress Trac]

#55443: Create WebP sub-sizes and use for output
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 Reporter:  adamsilverstein                      |       Owner:
                                                 |  adamsilverstein
     Type:  enhancement                          |      Status:  assigned
 Priority:  normal                               |   Milestone:  6.0
Component:  Media                                |     Version:  trunk
 Severity:  normal                               |  Resolution:
 Keywords:  has-patch has-unit-tests needs-      |     Focuses:
  testing needs-dev-note needs-docs needs-codex  |  performance
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Comment (by adamsilverstein):

 > When converting medium-resolution photographs (approx 1600px – 2500px on
 the long edge), WebP files are often larger than the JPEG equivalent. (In
 my tests using my own photography, in around 60% of cases.) This change
 might make the “modern image format” test of Page Speed Insights happy,
 but enforcing WebP by default on sites which use a lot of photography will
 often cause longer image loading times.

 Hey @markhowellsmead - thanks for the feedback. Are you comparing
 compression you achieve on your own desktop machine or on your WordPress
 site? WordPress may not show the same results for the sub-sizes it
 generates, since the compression relies on GD/Imagick which may not have
 the latest compression algorithms. If you are compressing, uploading and
 using the "original" uploaded image you may indeed be able to get better
 sizes with JPEG, however that isn't the way most images are used (instead,
 users upload large originals and WordPress compresses various sub sizes
 for display). Could you describe your workflow (and also what compression
 approach you use, is it MozJPEG?)?

 Part of this proposal includes storing the generated file size, one thing
 we are considering is always choosing the smaller image (at display time),
 especially since compression effectiveness can vary by image and size.

 Could you provide a sample original image we could test with where the
 WebP version is larger?

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Ticket URL: <https://core.trac.wordpress.org/ticket/55443#comment:17>
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