It is true that someone "hung" the picture in the past, and it is also true that the picture was "hung" (passive participle) by someone, nevertheless we still use the present / active participle to talk about the picture's present location. In English, we usually use the present participle to indicate location: Hanging, standing, sitting, lying. Other European languages (such as French) would indeed use the past / passive participle. Note that the English verb “hang” can be used in active voice (Ivy is hanging the picture), passive voice (the picture is being hung by Ivy), and *middle voice* (the picture is hanging).