Switching image URLs with multiple CDN subdomains

When images on a site are placed on multiple CDN subdomains, how can the code referenced in the API (https://yoast.com/wordpress/plugins/seo/api/) be implemented?:

function wpseo_cdn_filter( $uri ) {
	return str_replace( 'https://example.com', 'https://cdn.example.com', $uri );
}
add_filter( 'wpseo_xml_sitemap_img_src', 'wpseo_cdn_filter' );

What if for instance you have image content served on both https://cdn-1.example.com, https://cdn-2.example.com, https://cdn-3.example.com,…?