I'm applying a new theme to my site, and the theme has a custom thumbnail size. I realize that
add_image_size() does the work of creating the custom thumb whenever a new post is created.
This in my theme's functions.php:
add_image_size('ttrust_threeColumn', 280, 170, true);
However, I have a bunch of old posts I need to create this thumbnail size for. These old posts have a filename stored in a custom "Thumbnail" field, e.g.:
I can grab that file path with this:
Now if I loop through all the old posts, how can I create the custom ttrust_threeColumn thumbnail size for each post?
I appreciate the help! I've tried a bunch of different functions and methods, but I can't seem to get a grasp on thumbnail creation for existing posts.