It is it legitimate? (Two Photographs)

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Is it legitimate to photograph the work of others and take credit for the resulting photograph? This question applies here and to another set of photos later this week. In my view, if the approach taken in the photograph is distinctive then the taking of photographs of graffiti and outdoor art is legitimate.  Equally true if more than one artist has been involved in the final product. Finally, if there is context or only a portion of the art is visible, I believe the photographer has the right to call the work his own.