Add the “picture-” suffix to all images when uploading to WordPress

I’m using this in my WordPress theme functions.php to sanitize all images filenames when uploaded:

function sa_sanitize_special_chars ($filename) {
    return remove_accents( $filename );
}
add_filter('sanitize_file_name', 'sa_sanitize_special_chars', 10);

Now, I need also to add the “picture-” prefix to all images when upload too. How can I do that (in functions.php)?