This is a method for the get gravatar image most easily and, this library have a feature, if in gravatar no exists an image for user email returns default image with username initials.
You can test example in this link (https://gravatar-url.herokuapp.com/examples/LibraryUse.php).
$ composer require jruedaq/gravatar-url
In your php file call autoload.php
require 'vendor/autoload.php';
getting a url image
$imageUrl = GetGravatar::getUrl(SessionData::get()->getFirstName(), SessionData::get()->getEmail(), 230);
Complete example
<?php
require 'vendor/autoload.php';
use jruedaq\GravatarUrl\GetGravatar;
$imageUrl = GetGravatar::getUrl("Juan David Rueda Quiroga", "jrueda@oneago.com", 230);
?>
<img src="<?php echo $imageUrl; ?>" alt="profile image">