Code-Snippets-Functions/Execute a function on a child site/Jetpack/exclude-external-images-from-cdn.txt

function jetpackblog_external( $skip, $image_url, $args, $scheme ) {
// Get your site URL, without the protocol
	$site_url = preg_replace( '~^(?:f|ht)tps?://~i', '', get_site_url() );

	/**
	 * If the image URL is from your site,
	 * return default value (false, unless another function overwrites).
	 * Otherwise, do not use the CDN
	 */
	if ( strpos( $image_url, $site_url ) ) {
		return $skip;
	} else {
		return true;
	}
}
add_filter( 'jetpack_photon_skip_for_url', 'jetpackblog_external', 9, 4 );