We let ds throw things. He can throw balls, pillows, stuff toys, scarves, various other "soft" things. If he throws something that he shouldn't throw (a wooden block, legos, etc) we tell him he can't throw x because someone could get hurt/something could get broken, but he can throw balls, pillows et al. Usually we tell him he can't throw x and then we ask "what can you throw?" If he throws the "inappropiate" thing again, he loses it. Sometimes that means it goes on top of the book shelf, sometimes I just put it away (today he wanted to throw a wooden egg, I took it from him and put it back in his play kitchen).
I think the logical consquence of throwing things at the picture, is not being in the room with the picture. Even if it is a "time out" if he can't be "trusted" to be in that room, he can't be in that room.