`  :The legal requirement is ``... You must ... provide, reasonable to the medium or means You are utilizing: (i) the name of the Original Author...`` (plus some other stuff).  This turns on the vague phrase ``reasonable to the medium or means You are utilizing``.  What is a ``reasonable`` way of providing attribution for images on a wiki?  We operate under the assumption that asking a user to click on the thumbnail in order to locate the attribution is ``reasonable``.  Hence the authorship information is always available (i.e. one click away), but it is often not presented alongside the thumbnail.  A dead tree analogy might be a textbook where all the photographers are cited in a separate list at the back of the book (a fairly common approach), but the reader has to make an effort to look up each image in order to find the attribution.  In that analogy the authorship information is similarly easily available but not immediately at hand.  Of course ``reasonable`` attribution may not necessarily be ideal from an image creator's point of view, since some individuals would presumably like their name immediately next to every image.  At the moment, we work under the assumption that having attribution statements on every thumbnail is not necessarily under CC-BY.  Someday, the courts may look at the issue and truly decide what is or is not ``reasonable`` attribution, but for the moment having the author's name be one click away is believed to be good enough.    `