# Automatically sets the image Title, Alt-Text, Caption & Description upon upload
add_action('add_attachment', 'pami_set_image_meta_upon_upload');
# Helper function
if (!function_exists('pami_image_meta_first')) {
  function pami_image_meta_first($my_image_title, $encoding = 'UTF-8') {
    $my_image_title = mb_ereg_replace('^[\ ]+', '', $my_image_title);
    $my_image_title = mb_strtoupper(mb_substr($my_image_title, 0, 1, $encoding), $encoding). mb_substr($my_image_title, 1, mb_strlen($my_image_title), $encoding);
    return $my_image_title;
  }
}
# Main function
function pami_set_image_meta_upon_upload($post_ID) {
  if (!wp_attachment_is_image($post_ID)) return;
  $my_image_title = get_post($post_ID)->post_title;
  // Sanitize the title: remove hyphens, underscores & extra spaces:
  $my_image_title = preg_replace('%\s*[-_\s]+\s*%', ' ', $my_image_title);
  // Sanitize the title: capitalize first letter of every word (other letters lower case):
  $my_image_title = str_replace('"', '', $my_image_title);
  $my_image_title = str_replace('«', '', $my_image_title);
  $my_image_title = str_replace('»', '', $my_image_title);
  $my_image_title = str_replace('—', '', $my_image_title);
  $my_image_title = str_replace(':', '', $my_image_title);
  $my_image_title = str_replace('  ', ' ', $my_image_title);
  $my_image_title = str_replace('   ', ' ', $my_image_title);
  $my_image_title = pami_image_meta_first(mb_strtolower($my_image_title));
  // Set the image Alt-Text
  update_post_meta($post_ID, '_wp_attachment_image_alt', $my_image_title);
  $my_image_title = mb_strtolower($my_image_title);
  $my_image_meta = [
    'ID' => $post_ID,
    'post_title' => 'Изображение — ' . $my_image_title, // Set image Title to sanitized title
  ];
  // Set the image meta (e.g. Title, Excerpt, Content)
  wp_update_post($my_image_meta);
}