Gravatar images in WordPress sites don`t have alt and title tags, with this plugin you can resolve this problem on your site.

Gravatar SEO

A light and simple plugin to insert automatically ALT & TITLE tags into Gravatar images in your site.

webriti

The SEO Optimized Images plugin lets you dynamically insert SEO-Friendly “alt” and “title” attributes to your images. Simply activate the plugin, provide the pattern, and you are ready to go.
The plugin dynamically replaces the “alt” and “title” tags. It does not make any changes to the database. This means that if you deactivate the plugin, everything will return to the original settings. 
With the plugin, you can insert an image name, a post title and a post category in the “title” and “alt” attributes of the image. 
Give SEO Optimized Images a try: we are sure you will like it!
In case you face any problem, contact us via the <a href="https://wordpress.org/support/plugin/seo-optimized-images" rel="ugc">Forums</a>.
<h4>GDPR-compliant</h4>
The plugin does not collect, store and share any user data, and is therefore GDPR-compliant.
<h4>Premium Version Features</h4>
★ Support for Featured Images 
 ★ Support for Woocommerce Product Images 
 ★ Support for Custom Post Type Images 
 ★ Custom Rules selectively add alt and title tags to images based on custom rules. 
 ★ 1 Year Support and Updates 
 ★ Support for popular page builders like Elementor, Site Origin etc
<h4>**Upgrade to pro**</h4>
Follow link to purchase premium version
<a href="http://webriti.com/seo-optimized-images" rel="nofollow ugc">Upgrade to the Seo Optimized Images Pro Version »</a>
<h3>External Resources</h3>
OptionTree Font: 
Copyright: (c) Derek Herman 
License: GNU General Public License v2.0 
Source: https://github.com/valendesigns/option-tree/blob/master/assets/css/ot-admin.css

Seo Optimized Images

Plugin is very light weight and ensure that images always have relevant alt tags.  

Adding alt tags is a great way to get additional traffic and this plugin makes it a breeze.

Light and Effective

The SEO Optimized Images plugin lets you dynamically add SEO-Friendly "alt" and "title" attributes to your images.

Gravatar SEO vs Seo Optimized Images