generated thumbnail images compression level with .webp images

phiw13 · 2025-08-12 06:13:50

I am always rather unhappily surprised with the size of the generated thumbnails when using .webp images – on average 30% larger than it should be. This happens both with the Textpattern generated thumbnails and those generated with the smd_thumbnail plugin.

I tried to find if Textpattern or the plugin somewhere set the compression level by I got nowhere. Is there a way to improve that.

(recent versions of PHP, Textpattern 4.9dev, GD in use)

Bloke · 2025-08-12 09:16:34

Leave this with me.

Bloke · 2025-08-12 10:38:41

This commit introduces the overridable TEXTPATTERN_THUMB_QUALITY constant. Add something like the following to your config.php:

define('TEXTPATTERN_THUMB_QUALITY', 60);

to lower the quality from its default value of 80 percent. The quality value is applied to JPG, WEBP and AVIF thumbnails.

phiw13 · 2025-08-12 11:37:19

Interesting, will check it out tomorrow.

phiw13 · Yesterday 01:52:12

Bloke wrote #340123:

This commit introduces the overridable TEXTPATTERN_THUMB_QUALITY constant. Add something like the following to your config.php:

define('TEXTPATTERN_THUMB_QUALITY', 60);...

to lower the quality from its default value of 80 percent. The quality value is applied to JPG, WEBP and AVIF thumbnails.

Sadly it doesn’t seem to change much to the file size. For a webp image I set it to 50 to match the setting used in Acorn. Recreating the 800*450px thumbnail (from a 1600*900px source image), I get a 12% reduction only (expected: 25%). Testing with a jpg with a setting at 70 again to match Acorn settings shows a slightly better result: a 10% file size reduction compared to the originally generated thumbnail.

Testing with the same webp image but with smd_thumbnail enabled and the profile configured to match shows better results (~20% less).

For the jpeg files it is still an improvement (the user/owner of the site most always deals with jpeg files).

Bloke · Yesterday 08:32:40

That’ll probably be down to GD then. We pass the quality setting to PHP in its relevant function signature and the rest is out of our hands.

Keep this feature? Revert it?

phiw13 · Yesterday 09:36:06

Bloke wrote #340208:

That’ll probably be down to GD then. We pass the quality setting to PHP in its relevant function signature and the rest is out of our hands.

Keep this feature? Revert it?

I still see a win for those jpeg with some 10~15% fat reduction compared to the default (using 70 instead of the default, 80).

Bloke · Yesterday 09:43:03

Fine by me. It stays :)

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#1 2025-08-12 06:13:50