When you like a media, the current showing url will be shared. The Like button shares always the current showing URL. Facebook checks the site if there are any open graph meta tags. These tags are set in the head of the HTML document, it stores amongst others the image that should be shown on facebook. If there are no open graph tags, facebook searchs for image in the site.
So if you would like to show the assoicated image on facebook, the image needs to be stored on an own page with an open graph image tag referring this image and thats not possible.