View source for Open Graph protocol integration

I want to do the integration, is there an easy way to get the first photo of a page from the template?

the idea is to be able to easily add these META:

%%(hl html)
<meta property="og:title" content="Example title of article">
<meta property="og:site_name" content="example.com website">
<meta property="og:type" content="article">
<meta property="og:url" content="http://example.com/example-title-of-article">
<meta property="og:image" content="http://example.com/article_thumbnail.jpg">
<meta property="og:description" content="This example article is an example of OpenGraph protocol.">
%%

Cheers

Semantic Markups
  * ((https://www.ogp.me/ The Open Graph protocol))
  * ((https://schema.org/docs/gs.html Schema.org))
  * ((https://search.google.com/test/rich-results Google Rich Results Test Tool))