[wp-trac] [WordPress Trac] #54356: Determine and apply best default quality settings for WebP images

[WordPress Trac]

#54356: Determine and apply best default quality settings for WebP images
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 Reporter:  adamsilverstein                      |       Owner:
                                                 |  adamsilverstein
     Type:  enhancement                          |      Status:  assigned
 Priority:  normal                               |   Milestone:  6.1
Component:  Media                                |     Version:  5.8
 Severity:  normal                               |  Resolution:
 Keywords:  has-patch dev-feedback has-unit-     |     Focuses:
  tests                                          |  performance
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Comment (by mikeschroder):

 Including my comment from the
 [https://github.com/WordPress/performance/issues/7#issuecomment-1224010310
 testing ticket here as well], for context:

 > Hi @adamsilverstein ! Sorry for the wait here.
 > I'm working on testing this, but having a hard time getting trunk to
 respect the filter. It's possible it's a local environment issue, but I'm
 not sure yet.
 >
 > In the meantime, I thought it'd be helpful to provide my current
 thoughts.
 > TL;DR: Based on testing so far: I'm not strongly opposed to 82, but I
 prefer a value a little higher: 84.
 >
 > The mean / median in the testing were very close to 82.
 > However, they included an an image that was an outlier, and very easy to
 compress (72 quality required).
 > If this is removed, the mean/median become 84.
 >
 > The image in the tests (a portrait) that required the highest value to
 match its equivalent 82 JPEG needed a WebP quality of 90.
 >
 > For this image, and similar ones, the quality of the resizes will be
 lower than it was previously.
 >
 > I like the idea of matching the intent behind WebP's design, but I think
 we should make sure that aligns with the quality users currently expect
 from JPEG resizes (Side-wondering: Do you know if that design was based
 off of resizing from lossless images rather than JPEGs?).
 >
 > I also don't know where 86 came from, but it seems remarkably close to
 the value required for JPEG resizes into WebP!
 >
 > All of that said, I'm going continue another visual test, like you asked
 previously, and I'll follow up again.
 > I'm going to verify that the editors we're using actually generate a
 different size based on 82 / 84, and see if those would be visually
 distinguishable, regardless of the better DSSIM.

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Ticket URL: <https://core.trac.wordpress.org/ticket/54356#comment:11>
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