If you are tired of seeing the same old default “log in” logo, then you can change that to display a logo of your choice. To change the logo, you need to create and copy the new custom logo.png image into the image file in your root folder then copy and paste the following code into your functions.php file.

wp_change_login_logo.php

// login page logo
 function custom_login_logo() {
 echo '<style type="text/css">h1 a { background: url('.get_bloginfo('template_directory').'/companylogo.png) 50% 50% no-repeat !important; }</style>';
 }
 add_action('login_head', 'custom_login_logo');