Hi Steve, thank you for your answer.

The images still is’nt displayed. My knowledge of PHP is not sufficient to solve this.
I have this to display the image uploaded with the cpt code above:

<?php $image_ids = get_post_meta($post_id, 'portret');   
		foreach ($image_ids as $image)
{
  $myupload = get_post($image); 
  $title = $myupload->post_title;
  $description = $myupload->post_content;
  $caption = $myupload->post_excerpt;
 
  echo 'title:' . $title;
  echo 'description:' . $description;
  echo 'caption:' . $caption;
 
  print_r($myupload); // Displays all data
}
?>