baquast

and a last correction to get the thumbs on the frontpage to be of the same size:

the rest to be added to functions.php should be:

function hatch_portrait_sizes() {

  add_image_size( 'archive-thumbnail', 220, 332, true );
  add_image_size( 'single-thumbnail', 640, 966, true );
}

This way, the archive thumbnail has the same ratio. This should also be changed in the home.php file, i.e.:

‘height’ => 332

a working example is on: https://www.finwiki.nl

actually it would be best to add the last part that should be added to functions.php to line 238.

Thank you for this improvement. I have a few clarifications for your instructions

1. This is done by copying post.php (in the wp-content/themes/hatch folder) and renaming the copied file to e.g. post-portrait.php and they editing line three to: * Template name posts: Portait

2. functions.php is also in the hatch folder. You should add these lines at specific points:

line 45: add_theme_support( 'get-the-portrait' );
line 58: add_action( 'init', 'hatch_portrait_sizes' );
line 116: the rest (or somewhere around there, don't put it inside another function)

3. This extension file is actually a copy of get_the_image.php which can be found in this folder.

Btw, how can we change the images to portraits on the front page?