There is nothing inconsiderate about using the cropped image "Lena". Nothing. It is not an offensive image. Only hypersensitive people who choose to be offended by everything find it offensive, and those people should be fought against, not placated.
Look, you're under no real obligation to stop being an inconsiderate asshole. I'm just pointing out that there are practical consequences.
You don't have to be offended by the image. You don't even have to understand why people are offended, that's fine. But if you don't take other people's feelings into consideration, that's the inconsiderate part.
Other people are going to have different opinions than you do. Telling other people they're not allowed to be offended is why you're an asshole.
I would be an inconsiderate asshole if the picture was actually offensive, ie, if it was goatse, someone in blackface, etc. But it isn't, and unlike you, I have the courage to make a statement about the image: that it is objectively not offensive. There is no one out there who is actually offended by it. They are all people pushing an agenda.
So your argument seems to be that because some people could be offended by it, we shouldn't use it, even though the notion that anyone could be offended by it is ridiculous on its face. So what, then, about things like gay pride parades? People can be offended by those, too. According to your argument, we should end that, too. But I'm sure you'd never advocate for that. You'd say something like "it's their right to be in your face in public". And of course it is, even though it can offend people. But that same argument defends people who'd use offensive images in image processing papers, not just ones which are just a target for politically correct assholes. You only care about people being offended if they're on your side.
Gay pride parades are not bad things, and just the same, a woman posing for Playboy is not a bad thing, and using the cropped image of the face of a woman's nude picture is even less offensive than a gay pride parade. And nobody should be pressuring anyone to stop either of those things.
I'm just saying that anyone who IS offended by it is a whiny, oversensitive asshole who wants to force the world to accommodate them, and that is wrong. Standing up to them does not make me the asshole: babying them makes you the asshole.
Edit: just take another look at the cropped picture "Lena". If your argument is that that is somehow offensive, you are wrong, plain and simple.
You can't understand the meaning of a symbol by studying the symbol. You have to go look at what it means. It's like analyzing a swastika and deciding that neo-nazis aren't offensive. The problem is that only men were part of that project, they treated a woman in an exclusive manner, and now that image is a reminder of that sexist hierarchy.