If content type conatins a Content Relations(Multiple) Field and after adding images as related objects to the content item . The content Preview output following error:

Variable "objectParameters" does not exist in EzPublishCoreBundle:default:content/embed_image.html.twig at line 7

Error demo at:
http://www.screencast.com/t/8XWANrc63

Error not happen when adding image to Content Relation (simple)

suggestion in embed_image.html instead of :
{ parameters:

}
{ parameters:

}
this will resolve the issue and output a simple image view.