og:image is not parsed correct if e.g. og:image:width exists on page

[vonholst]

og:image is parsed correctly at first
if there are more og:image attributes, e.g. og:image:width it replaces the image attribute.

[vonholst]

I would suggest the following modification:
opengraph_dict.update({u"_".join(attr.split(":")[1:]): value})

This will yield image, image_width, image_height, ...