Enrico Sorcinelli

Feature Image Extended extends featured image functionality allowing:
<ul>
<li>Hiding featured image in your themes for all post types.</li>
<li>Adding link to the featured image.</li>
<li>Adding thumbnail featured image in administration screens listing.</li>
<li>Featured image quick-editing.</li>
</ul>
<h3>Usage</h3>
Once the plugin is installed you can control settings in the following ways:
<ul>
<li>Programmatically by using <code>featured_image_extended_settings</code> filter (see below).</li>
<li>Using the Settings->Featured Image Extended administration screen.</li>
</ul>
If your theme uses a different call other than <code>the_post_thumbnail()</code>/<code>get_the_post_thumbnail()</code> in order to get the featured image, this plugin might not work. 
So, in order to get extended featured image settings and apply to your pages, you should use <code>featured_image_extended()</code> (see below).
<h3>API</h3>
<code>featured_image_extended( integer $post_id = null )</code>
It returns an array containing featured image extended information of <code>$post_id</code> post (or current post if you don’t supply an argument) like following:
<pre><code>array(
 'show' => true,
 'url' => 'https://myurl.com',
 'target' => '_blank',
 'title' => 'Image title',
)
</code></pre>
<h4>Hooks</h4>
<code>featured_image_extended_settings</code>
Filter plugin settings values.
<pre><code>apply_filters( 'featured_image_extended_settings', array $settings )
</code></pre>
<code>featured_image_extended_admin_settings</code>
Filter allowing to display or not the plugin settings page in the administration.
<pre><code>apply_filters( 'featured_image_extended_admin_settings', boolean $display )
</code></pre>

Featured Image Extended

Feature Image Extended extends featured image builtin functionality.

ryanshoover

Cousett

Easily display a mobile featured image on your posts and page!
Up to 70% of website traffic today is on mobile devices. Sometimes WordPress does not quite resize the featured image in the best way. Avoid this and have full control over your featured images on any device with this plugin.
To add a mobile featured image, simply upload a new image in the meta box right below the WordPress Featured Image called Mobile Featured Image. The new image can be a specifically resized version of your featured image or an entirely new image targeted especially for mobile viewers.
You can add your mobile featured image without worrying about slowing down your site. The mobile image is added to the <code>srcset</code> attribute of your featured image. Vistors’ browsers will automatically download the best image for the size of their screen.
This plugin works by filtering the <code>wp_calculate_image_srcset</code> function and changing the url for all screens under 980w to the mobile featured image. 980w is a reliable breakpoint between the iPhone 6+ and the iPad, two common measures for when a mobile image would be needed.

Featured Image Extended vs Mobile Featured Image