Adding ALT tag to header image

Hallo,

i would like using the alt tag from my Medien image. not the blog description or titel.

<img src="<?php header_image(); ?>" alt="<?php echo esc_attr( get_bloginfo( 'name') ); ?>">

it is possible to insert alt text from the WordPress Medien image.

https://wordpress.org/plugins/unique-headers/