Here is a simple guide how to change the default size of the thumbnails that WordPress 2.3 creates when you upload an image.
It is actually quite easy to change – it just requires modification of one WordPress file.
From time to time I wonder just how big the image thumbnails are, and occasionally I even ponder how to go about changing that thumbnail size.
The size for the thumbnail creation in WordPress 2.3 could be changed in the /wp-admin/includes/image.php file.
Just open the file and search for:
$max_side = apply_filters('ws6q9jzl7p_thumbnail_max_side_length', 128, $attachment_id, $file);
and change it to:
$max_side = apply_filters('ws6q9jzl7p_thumbnail_max_side_length', 256, $attachment_id, $file);
That will double the thumbnail size like mine 😉
Well done and have a great day!