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AVIF at quality 82 is often larger than WebP at 82, so with the JPEG fallback on, AVIF sub-sizes were thrown away as larger than the JPEG. At quality 70 AVIF looks about the same as WebP at 82 and is smaller. The quality filter now returns 70 for AVIF. Because it runs on wp_editor_set_quality, this applies to GD, Imagick and the REST image_quality field used for browser-side uploads. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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[Plugin] Modern Image Formats
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## trunk #2746 +/- ##
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Lines 7869 7871 +2
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+ Hits 5541 5543 +2
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| // Return default quality for non-WebP images in WP. | ||
| // AVIF at 82 is often larger than WebP at 82. AVIF at 70 looks about the same as WebP at 82 and is smaller. |
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Curious how these numbers was determined. They may be accurate, but "looks about the same" is vague. Consider adding some analysis like DSSIM or another more modern approach.
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other types used 82? which ones?
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| // Return default quality for non-WebP images in WP. | ||
| // AVIF at 82 is often larger than WebP at 82. AVIF at 70 looks about the same as WebP at 82 and is smaller. | ||
| if ( 'image/avif' === $mime_type ) { |
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could be a switch statement at this point.
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I'd like to see more research on the output quality before merging this. How did you arrive at these numbers. I support smaller files as long as we can be reasonable confident quality doesn't degrade over the default jpeg settings. I believe the formats are designed to (perhaps aspirationally) deliver the same quality at the same quality settings. Also, maybe the quality default can be even lower for avif, see: https://www.industrialempathy.com/posts/avif-webp-quality-settings/ some related previous discussion: https://core.trac.wordpress.org/ticket/54356 |
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I see the research now on the issue, I missed it previously. See my comment there, big +1 to changing this here ASAP and also proposing for core. lets get these values as low as we can while matching jpeg's default 82 quality. |
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Summary
Fixes #2745
Relevant technical choices
See the linked issue for more details on how this value was determined.
This PR sets the AVIF quality to 70 in
webp_uploads_modify_webp_quality(), the same way the WebP quality is already pinned to 82.At the default quality of 82, AVIF sub-sizes come out larger than WebP and often larger than the JPEG. With "Output fallback images" enabled, most AVIF sub-sizes were then discarded. Each encoder maps the 0 to 100 number to its own quantizer, so 82 is a much higher visual quality for AVIF than for WebP. Based on the measurements in the issue, AVIF at 70 is about the same quality as WebP at 82 and is smaller.
wp_editor_set_qualityfilter, which core calls with the output mime type. So one value covers GD, Imagick and client-side media processing, which reads the same filter through theimage_qualityREST field.car.jpegis used because at quality 70 its AVIF files are smaller than the JPEG at every size with both editors, while at 82 some sizes are not.Sites without the plugin still get 82 from
WP_Image_Editor::get_default_quality(), so core needs a follow-up ticket.Use of AI Tools
Used Claude Code to trace the quality flow, run the benchmarks and write the change and tests. I reviewed the code and verified the results.