Documents and files with the same mimetype should have the same summary view

If you create a document type image, the summary will display a preview thumbnail.
If you create a file containing an image, there won't be any preview displayed.

As a user point of view the same document created through a file, a specific type or even by drag and drop should have the same summary view. No matter if you add, create, drop or import a document, the extension should "decide" which facet to use (image, video, office docs, note, …).