Add filter for Divi image sizes

functions.php

add_filter('et_theme_image_sizes', 'return_my_image_sizes');

function return_my_image_sizes( $sizes )
{
	$image_sizes = array(
		'400x250'   => 'et-pb-post-main-image',
		'1080x675'  => 'et-pb-post-main-image-fullwidth',
		'400x284'   => 'et-pb-portfolio-image',
		'510x382'   => 'et-pb-portfolio-module-image',
		'1080x9999' => 'et-pb-portfolio-image-single',
	);
	return $image_sizes;
}