Studiofreya

SF Generate Tags is a plugin that helps generate tags for posts. It scans the names of all attached images and/or the post content (text) and places the resulting tags in the built-in WordPress “Tags Widget” in the post editor. 
The plugin analyzes collected words and picks out the most suitable for tags. 
All tags are then sorted in descending order and posted into the Tags widget. 
If you don’t like a tag which has been discovered and want to delete them, you can just click the X button and save post without them. 
The plugin doesn’t mess with your existing tags. It preserves all your existing tags for the post. All the actions can be easily undone.
This plugin should work with any language. It’s filtering algorithm is designed for English. All other languages will have all the words be added as tags.
<a href="https://studiofreya.com/wordpress/sf-generate-tags/" rel="nofollow ugc">SF Generate Tags website</a>
<h4>Features:</h4>
<ul>
<li>Easy to use from the admin panel for post edit </li>
<li>Choose to generate tags from attached images or post text or both</li>
<li>Exclude words that you don’t want to be tags</li>
<li>Easy to remove all undesirable tags</li>
<li>All actions can be undone</li>
<li>Existing tags are preserved</li>
<li>Add other tags later</li>
<li>Regenerate tags after updating the post (or not)</li>
<li>Limit number of generated tags</li>
</ul>

SF Generate Tags

Generate tags for posts from images or/and post text.

Hesham Zebida

The plugin adds more functionality to the <a href="http://www.studiopress.com/" rel="nofollow ugc">StudioPress</a> Generate Child Theme.
This plugin is a very handy tool for Generate Child Theme users, it allows you to display the Generate Box on front page, home page, single posts, and everywhere. It also has an option to switch between different color schemes with only a few clicks.
See live example of <a href="http://generatebox.com/" rel="nofollow ugc">Generate Box</a>.
<h4>Credit</h4>
The Generate Box was designed by <a href="http://twitter.com/rafaltomal" rel="nofollow ugc">Rafal Tomal</a>, lead designer of <a href="http://www.copyblogger.com/" rel="nofollow ugc">Copyblogger Media</a>, and coded by <a href="http://www.famousbloggers.net/" rel="nofollow ugc">Famous Bloggers</a>.
=Resources= 
You can download <a href="http://www.studiopress.com/graphics/generate-box" rel="nofollow ugc">PSD</a> here.

Generate Box

More functionality for the StudioPress Generate Child Theme.

SF Generate Tags vs Generate Box