Many of the newer SE2.0 sites are well-suited to questions and answers containing images, and I love that many users use images in their posts. It can add value both for context and aesthetics. Examples:

(ok, the last two are mine)

But, I think the licensing issue is a bit worrying. Obviously Stack Exchange is very aware of licensing and all content posted by users is licensed under CC BY-SA 3.0. However, there is little control over ensuring that users hold the right to license the images they post, and many images are of dubious source.

Wikipedia has extensive image use policy to ensure that the images that make it onto the site are allowed to be there. Images must be accompanied with sourcing info when uploaded.

As far as I know, Wikipedia images are free to be used here, and there are many great images available on Wikipedia, but we can't know that that's where they are from unless the user says so. And, the license most likely requires linking to the source/author.

  • Should Stack Exchange require that images not owned by the user be accompanied with source and/or licensing info, and what do we do about existing unsourced images?
  • What is the proper way to indicate the source or license of the image?
  • (Added after Adam's answer) If requiring licensing info seems too onerous, should SE at least suggest or recommend sourcing so that images that are completely valid (i.e. Wikimedia Commons) have the proper attribution and the posts that use them can be worry-free should future issues arise?*

* I would recommend this approach at the very least, since if SE ran into image licensing troubles in the future, finding the source after-the-fact would be near impossible and unreferenced images would simply have to be removed.

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    How would this apply to simple things like screenshots? IANAL, but Licensing or even just sourcing a screenshot that I take to, say, illustrate an answer or demonstrate a bug seems excessive. "Source: me" is a bit silly. – Adam Lear Aug 11 '11 at 1:57
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    As I understand it, the SE people cry "Fair use!" and do some handwaving. They'd probably be the ones getting in legal trouble, if anyone, so I'm happy to let them ignore the potential problem. – user154510 Aug 11 '11 at 2:10
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    @Anna I'm not suggesting we throw common sense out the window. All content that you post to any SE site is licensed by you under the terms of service of the site. That's already taken care of. The problem occurs not when you took a screenshot, but when you don't have a right to re-license the content. – Nicole Aug 11 '11 at 3:15
  • @Matthew That's fine, but I'm more concerned about future-proofing the quality of posts with nice images, not providing a legal defense for SE the company. – Nicole Aug 11 '11 at 3:17
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    Just to be clear, are downvoters suggesting that the status quo - stealing images from anywhere is fine - should be maintained? – Nicole Aug 11 '11 at 3:35
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    @Renesis Are you suggesting that we should treat users as copyright infringers unless they provide documentation? Keep in mind that while Stack Exchange provides an easy way to use imgur to store images, Stack Exchange itself does not store those images, they only store a link to them. The link itself is licensed CC, not necessarily the image. So honestly I don't think that there's any liability at all. If the image gets taken down, Stack Exchange has a broken link in its CC licensed material, but it's not storing or distributing the images, only pointing to them. – Pollyanna Aug 11 '11 at 3:40
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    @Adam Actually, I'm suggesting that SE help users source their images (with a suggested format or help text or whatever) so that we keep the site looking good in any number of what-if scenarios. I'm not suggesting anything drastic, but I think that we should be a little bit concerned with attribution the more common the practice of including a nice image becomes on sites such as Travel.SE. My question really is a question. – Nicole Aug 11 '11 at 3:47
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    @Renesis I'm not in the downvoter camp, but the status quo isn't that stealing images is fine. It's not fine and it's against the ToS. Having someone fill out a textbox during upload isn't likely to be an improvement without validation and enforcement though, so I'm not sure how useful these changes would be if implemented. – Adam Lear Aug 11 '11 at 3:53
  • @Anna They'd probably be used about as often as the edit comments box is - rarely. Further, it would only provide more ammunition to the various copyright associations if they did bring a case against Stack Exchange. If we don't collect the information, and we enforce the TOS when infringment is found, we are relatively safe from many types of lawsuits. If we start to collect source information and attempt to enforce copyright then we implicitly accept some liability for infringment, which means that even if we comply with takedown notices, we could be sued for damages. – Pollyanna Aug 11 '11 at 3:59
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    Youtube found this out the hard way. Any pre-emptive action you take can and will be used against you in a court of law. It's not feigning ignorance - it's asserting that we are merely a "forum" where individuals post text and links, and we don't police that content for copyright violations. The violation occurs with the person who submits the content, not the carrier (stack exchange, in this case). We are further protected by the fact that we don't store or distribute the images themselves. All in all, I think this is a great example of overkill for absolutely no gain. – Pollyanna Aug 11 '11 at 4:00
  • @Adam I agree, especially with the "providing ammunition" part. – Adam Lear Aug 11 '11 at 4:03
  • @Adam doesn't SE's dedicated imgur storage put a wrinkle in that? Or is that just a technical optimization? – Nicole Aug 11 '11 at 4:32
  • @Renesis You'd have to ask the lawyers, now you're getting into the nitty-gritty, and I'm only generalizing based on past copyright user-generated-content vs common-carrier cases such as Youtube, Napster, and the torrent sites. Each case is unique and depending on where the case is heard there are minor differences as well. – Pollyanna Aug 11 '11 at 4:41
  • @Renesis, here's one of mine. I have to admit I just googled for the images... – Benjol Aug 11 '11 at 5:36

If Stack Overflow starts to actively police image licensing, they may actually create more liability for themselves. They're going to have to discuss this with their legal counsel, but most sites are better off requiring their users only post content they have the rights to post, and having a policy of quickly responding to DMCA notices.

You'll note that this is the current path that Stack Exchange currently takes via their terms of service, in section 3: https://stackexchange.com/legal

I think requiring users to add attribution notices to each image they post is a bit too far, and as you note would create a huge logistical problem for existing content, not to mention cluttering the posts with meta-content that doesn't materialy have anything to do with the question or answer.

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    What you say as logical, but using images with disregard to attribution and licensing until served with a take-down notice seems a bit wrong. – Nicole Aug 11 '11 at 1:46
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    @Renesis I suppose the question comes down to trusting the users and letting them do their thing unimpeded, or switching to a policy of not trusting them, and forcing them to justify their rights every time they post an image. The various content rights associations have really worked hard to make people think that it's better to mistrust users and require additional info before the violation, but in general I'd rather take an innocent until proven guilty stance. Treat the users as intelligent people who will do the right thing, and follow up when they don't. – Pollyanna Aug 11 '11 at 1:56
  • I'm not sure it has anything to do with forcing them to justify their rights. If they really do have the right there is no problem. This mostly have to do with photos. Anywhere but Photography.SE it's very unlikely anyone is using their own, and the rights of the authors of those works should be respected. – Nicole Aug 11 '11 at 3:38
  • @Renesis What kind of images do you have in mind? I don't see many in my daily use of SE at all. – Adam Lear Aug 11 '11 at 3:51
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    "Anywhere but Photography.SE it's very unlikely anyone is using their own" Ah, you are of the opinion that people are stealing more often than not. – Pollyanna Aug 11 '11 at 3:52
  • @Adam Photos, yes. Do you disagree? – Nicole Aug 11 '11 at 4:29
  • @Anna those like in the links in the question. Images representative of a place, a flower, a product, etc. – Nicole Aug 11 '11 at 4:31
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    @Renesis I'm talking about all images, not just photos, and my experience on the technical sites suggests that most images are obviously created for the question - screenshots, diagrams, etc. So I'd have to say that I do disagree with your assessment. But - the point is that Stack Exchange shouldn't be in the business of policing copyright - even if you could show that significant copyright infringement was occuring that wasn't fair use, it still wouldn't be a good idea to collect information - again, that just increases the site's liability, which is detrimental to the site and its users. – Pollyanna Aug 11 '11 at 4:36
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    I'm terrible at asking questions that reflect what I'm really looking for. I'm not hoping for policing, but for "what to do when you see that obvious stock image" or "should I suggest to other users that they use free images and include attribution". – Nicole Aug 11 '11 at 4:47


The biggest reason I prefer Stack Exchange to alternatives, and evangelize about it whenever appropriate, is the fact that contributed content is open (CC BY-SA 3.0)

I contribute detailed answers because the resulting QA is open, and like many coders I think that openness is the best way to make knowledge available. Anyone in any country can copy content to their USB sticks, print it on paper, publish an ebook about a particular topic, and reuse what I contributed in useful ways that I would never have imagined.

Consequences of mixed content

Having non-free images prevents reuse. Suddenly, that ebook can not be publish anymore. Non-compatible images have to be stripped, often leading to incoherent content. The usefulness of our contributions gets reduced.

So, we should strive to embed images that are compatible with CC BY-SA 3.0.

To reach this goal, keeping track of the license of each image is important. Writing this information under the image, or as the alt comment of the image, are the only two options right now. Ideally, the Stack Exchange UI could be updated to make this easier and more semantic, for instance by extracting this information automatically when inserting an image from a Wikimedia Commons URL.

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