wordpress_html5_insert_image_figure.php

<?php

/**
 * Change image tag
 */


add_filter( 'image_send_to_editor', 'html5_insert_image', 10, 9 );

function html5_insert_image($html, $id, $caption, $title, $align, $url, $size, $alt) {
  $src    = wp_get_attachment_image_src( $id, $size, false );  
  $html5  = "<figure id='post-$id media-$id' class='align-$align'>";
  $html5 .= "<img src='$src[0]' alt='$alt' />";
  if ($caption) {
    $html5 .= "<figcaption>$caption</figcaption>";
  }
  $html5 .= "</figure>";
  return $html5;
}