WordPress.org

1. Upload the file post-attached-image.php to the /wp-content/plugins/ directory
2. Activate the plugin through the "Plugins" menu in WordPress
3. Configure the plugin in the "P-Image" menu located under the WordPress "Options" menu

If image can't be uploaded is needed to edit a little file /wp-admin/edit-form-advanced.php at line 12. It is because your browser can't set encoding type using javascript. form must be form enctype="multipart/form-data" Without this string file will not be uploaded.