Yes, there is possible.
Inside the functions.php
add the follow source.
add_action( 'after_setup_theme', 'twentyfourteen_default_header' );
/**
* Add Default Custom Header Image To Twenty Fourteen Theme
*
* @return void
*/
function twentyfourteen_default_header() {
add_theme_support(
'custom-header',
apply_filters(
'twentyfourteen_custom_header_args',
array(
'default-text-color' => 'fff',
'default-image' => get_stylesheet_directory_uri() . '/images/default_header.jpg',
)
)
);
}
Now was the set the default image, from the path. The rest is a little bid css magic to set to your requirements. Alternative you can set also a image via CSS, but is not so easy to change for the theme users. With this function you set a default and the custom possibilities like Customizer or via back end is also possible.