This is a sample from the open graph protocol's homepage
<html prefix="og: http://ogp.me/ns#">
<head>
<title>The Rock (1996)</title>
<meta property="og:title" content="The Rock" />
<meta property="og:type" content="video.movie" />
<meta property="og:url" content="http://www.imdb.com/title/tt0117500/" />
<meta property="og:image" content="http://ia.media-imdb.com/images/rock.jpg" />
</head>
<body></body>
</html>
...copy/paste that in Google's Structured Data Testing Tool. Hit submit, and nothing.
Now try this in Google's Structured Data Testing Tool:
<!DOCTYPE html>
<html xml:lang="en" lang="en">
<head prefix="foaf: http://xmlns.com/foaf/0.1/ og: http://ogp.me/ns#" typeof="foaf:Document">
<meta charset="utf-8" />
<title property="og:title">The Rock (1996)</title>
<meta property="og:type" content="video.movie" />
<link property="og:url" href="http://www.imdb.com/title/tt0117500/" />
<link property="og:image" typeof="foaf:Document" href="http://ia.media-imdb.com/images/rock.jpg" />
<meta property="og:description" name="description" content="A movie..." />
</head>
<body>
<link property="og:image" typeof="foaf:Document" href="http://www.imdb.com/images/SeanConnery.jpg" />
</body>
</html>
See the problem? You don't get the second pic, "SeanConnery.jpg" because it's out the scope of the namespace, and no, you can't put it on the <html>tag, only the namespace http://www.w3.org/1999/xhtml/ is allowed there.
So, in order to do this properly with your situation (of the images being only in the <body>) you would have to move all the properties to the <body>
<!DOCTYPE html>
<html xml:lang="en" lang="en">
<head>
<meta charset="utf-8" />
<title>The Rock (1996)</title>
<meta name="description" content="A movie..." />
</head>
<body prefix="foaf: http://xmlns.com/foaf/0.1/ og: http://ogp.me/ns#" typeof="foaf:Document" resource="http://www.imdb.com/title/tt0117500/">
<meta property="og:type" content="video.movie" />
<link property="og:url" href="http://www.imdb.com/title/tt0117500/" />
<link property="og:image" typeof="foaf:Document" href="http://ia.media-imdb.com/images/rock.jpg" />
<meta property="og:description" content="A movie..." />
<img property="og:image" typeof="foaf:Document" src="http://www.imdb.com/images/SeanConnery.jpg" />
</body>
</html>
BTW, images and movies are sub-classes of foaf:Document