I personally like how you can choose to show a post’s image to show up in it’s own attachment page, yet I noticed sometimes it shows the medium size of the image. If you want to show the ‘full’ size of the image, I found a quick workaround.
In the wp-includes folder, make the following change to the post-template.php file.
Look for “medium” in the following chunk of code:
$p .= wp_get_attachment_link(0, 'medium', false);
and change it to “full”
$p .= wp_get_attachment_link(0, 'full', false);
This is a core wordpress file, so keep in mind, when you update your wordpress version, you’ll have to re-do this fix. Does anyone else know how to do this same thing without having to touch core wordpress files? If so, please leave a comment! Thanks!