[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:  6.1
Component:  Media                                |     Version:  6.0
 Severity:  normal                               |  Resolution:
 Keywords:  has-unit-tests needs-dev-note        |     Focuses:
  needs-docs needs-user-docs needs-patch 2nd-    |  performance
  opinion needs-testing changes-requested        |
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Comment (by eatingrules):

 Thanks for doing those comparisons, Adam.

 Creating only WebP thumbs definitely tempers my concerns about disk space
 issues, as I'm coming around to the idea that it could solve some problems
 by not having both types of images stored on disk. But, questions remain:

 **How will dealing with thumbnail regeneration work?**

 If regenerating is suddenly going to add WebP thumbs for all images in an
 existing library, that will suddenly use ~70% more disk space.
 Regeneration is common enough that this really needs to be considered and
 planned for.

 I don't think it will be safe to delete the old JPG thumbs as new WebPs
 are generated, since there could very likely be links directly to the JPG
 images.  So how to prevent a sudden and unexpected massive increase in
 disk space for site owners?

 (And it's not just when installing a thumbnail regeneration plugin.
 WooCommerce, for example, can regenerate thumbnails in the background --
 completely unannounced. Woo is running on 5+ million sites!)

 ** Could you maybe share some sample images from the tests so we can get a
 sense of the visual quality loss (if any) for each of the compression
 levels?**

 I know each site owner may have a different tolerance for quality loss,
 but seeing the differences may help us choose a default compression
 setting -- rather than basing it solely on % of space savings.

 ** What about images other than photos? **

 From the repo it looks like you tested with photos from unsplash.com.
 What about other image types, like drawings, line-art, logos, or
 screenshots? Or "Pinterest images" (which are typically photos with text
 overlaid)?

 **What happens when users Right-Click->Save as, and they get a WebP
 instead of a JPG?**

 Of my concerns, this is the most minor - but it speaks to the client's
 understanding what their site is doing and having control over it.  If
 they opt-in to the WebP feature then they can be informed at that time
 what will be happening, and will ''expect'' to see this new/different
 format, rather than just being confused or frustrated by it.

 ** Is the plan still for this be enabled by default?**

 Making these features ''opt-in'' solves a lot concerns, since it puts the
 site owner back in the driver's seat.

 **Will there be any user interface for turning this on or off?**

 **What happens to existing images/thumbnails when it's enabled?
 Disabled?**

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Ticket URL: <https://core.trac.wordpress.org/ticket/55443#comment:145>
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