admin-logo.php

<?php

// CUSTOM ADMIN LOGIN HEADER LOGO
   function my_custom_login_logo() {
    echo '<style type="text/css"> h1 a { background-image:url('.get_bloginfo('template_directory').'/images/democratic-post-logo-google.jpg) !important; } </style>';
   }
   add_action('login_head', 'my_custom_login_logo');

// Die URL des Logos auf die eigene Website zeigen lassen 
function gp_change_login_page_url($login_header_url) {
    return get_bloginfo( 'url' );
}
add_filter( 'login_headerurl', 'gp_change_login_page_url' );

//Den Seitentitel des Logos ändern
function gp_change_login_page_title($login_header_title) {
    return get_bloginfo('title');
}
add_filter( 'login_headertitle', 'gp_change_login_page_title' );