David's point is coherent with what I experienced when one of my photographs was used improperly without autorisation. The journalist to whom I wrote claimed that it was my responsability to state my name for credits to be given.
Her arguments surprised me (beside being legally bizarre) as my name was indeed stated under the image. But only the Commons image page, which you reach by clicking on the image, not on the article itself. I also suspect that they used the small resolution image which appears on the article, rather than the higher resolution available on Commons.
-- Rama