Plagiarism of images and photographs is really no different than plagiarism of words, music, or any original work. Copying an image from a book or the internet without citing the original source (or gaining permission of the creator when necessary) constitutes plagiarism.
In this case, the painting (left) is identical to the photograph but is flipped. It appears the exhibition organizer in Luxembourg has removed any mentions of the painting.
Whether Ms Zhang takes legal action or not is unknown at this time...however I believe the painter has sullied his artistic reputation in his home country of Luxembourg, especially as the offense has been mentioned a number of times in art-related peiodicals.
