Social media sites often use the "image_src" microformat for displaying link thumbnails. This simple plugin adds the image_src rel value to the code of your site. By default, the plugin applies only to singular views and it uses the featured image. It only applies when an image is available.

1. Go to: WordPress > Plugins > Add New > and find "image_src"
2. Activate via WordPress > Plugins > Installed Plugins

Requires: PHP 5.3+

The @image_src filter hook allows for image customization and/or extending the plugin to views without a featured image:

add_filter('@image_src', function ( $src = '' ) {
  return $src ? $src : '/example.png';
});

Copyright (C) 2013 by Ryan Van Etten