was from the text used in a graduate-level data communication course I took many, many years ago. It said, more or less, that "Communication requires three things: a shared model, a shared set of symbols, and a common system for associating symbols with objects from that model."
Now here's the thing that I think is wise about that idea. People respond as if something like a famous photograph has an objective meaning and that everyone *should* somehow all have the same reaction to it. But intelligent, educated people should know better than that. Personally, I see a considerable element of self-deprecating humor in this particular choice of photo. However nobody should be particularly surprised that not everyone is laughing.
After many years of watching people drag out the pitchforks and torches when they're offended, or man the ramparts when they're offended by that offense, here's what I think the sensible way to handle this kind of thing is. When you feel offended by something someone says, say so, but without accusing the sayer of bad faith or collusion with the Forces of Oppression. When you have given offense you apologize and express yourself a different way.
You have a choice: you can either accept that people coming from different experiences will view things differently than you and work around that; or you can try to convince everyone in the world to think and feel the same way you do about everything.