How to set author for post AND post attachments

I have multiple author accounts on one of my WordPress installs. Often I will create a post, and set the author to be a different account. However, when I upload images into that post, their attachment page lists the author as my account. How can I set the author for posts, and have it carry over to the media associated with that post?

Use this in your theme’s functions.php:

add_filter( 'add_attachment', 'wpse_55801_attachment_author' );

function wpse_55801_attachment_author( $attachment_ID ) 
{
    $attach = get_post( $attachment_ID );
    $parent = get_post( $attach->post_parent );

    $the_post = array();
    $the_post['ID'] = $attachment_ID;
    $the_post['post_author'] = $parent->post_author;

    wp_update_post( $the_post );
}