Workaround for JetPack site accelerators causing full-size images to shrink when enabled

Sep 6, 2020 PHP WordPress Jetpack

Problem

When JetPack’s Site Accelerator </ q> and Speed up static file loading </ q> are turned on in WordPress, the width of the image loaded in the post will be reduced. Image size </ q>: Even if you specify Full size </ q>, it will be reduced to 1024px.

Cause

JetPack refers to global $ content_width to determine the maximum width of the image ¹.

How to solve

Add the following contents to functions.php etc. and overwrite $ global $ content_width ².

<? php
// ...

(function () {
global $ content_width;
$ content_width = 1920; // Specify the maximum expected width of the image.
}) ();

// ...

Remarks

In the future ³, it may be possible to change global $ content_width withadd_theme_support ()⁴.

Reference page

• Full image size (Gutenberg block “image”) is not full size but limited at 702px · Issue # 13433 · Automattic / jetpack.
• Content width-WordPress Codex Japanese version.