post_type: attachment

Hello
quick question – I got the plugin to show attachments – that was quite easy – thanks for that – however, I was wondering how I actually could display the attachment / image – I’m using a template and by setting a global $post, I think I’m actually able to get the post ID/attachment ID – is that the right way to do it – I don’t see that the post ID is actually passed to the “display_posts_shortcode_output” filter.

thanks again for your help