Within this update, they added a feature that forces large images to scale down in size to be “web-ready.” So if an image is larger than the default threshold (2560px), WordPress will automatically scale it down.
As I’m sure you already know, large images are problematic because they can impact the loading time of a website, which in turn harms SEO and user experience and takes up a lot of space on the server.
Now, I do understand why WordPress has added this feature. Many WordPress users upload images to their website directly from their camera or a stock image website, which are often huge! However, there are times when we do want to upload large images to our WordPress websites, despite knowing that they will slow down our websites, and we don’t want WordPress to stop us from doing so.
I found out how to easily remove this new image scaling functionality. I thought I’d share my knowledge just in case you have problems uploading images to WordPress.
This post will show you how to stop WordPress from scaling large images after the version 5.3 update.
Paste in this add_filter() function
To access the functions.php file via the WordPress admin area, hover over Appearance in the left-hand menu of WordPress and click on Theme Editor.
If you can’t see the Theme Editor option, it may have been disabled either using a plugin (usually a security one), via the theme, or via some code in your website files. You may need to contact a developer if you’re unsure how to access this.
Once the Theme Editor is open, click on Theme Functions (function.php) on the right-hand side of the screen. This will open up the functions.php file.
If you are using a pre-made WordPress theme and aren’t already using a child theme, I highly recommend setting up one and editing the functions.php file of the child theme rather than the main-0parent theme.
Open up your functions.php file
add_filter( 'big_image_size_threshold', '__return_false' );