Is it unprofessional to use graphics from Wikipedia in a poster?
The primary issues with using Wikipedia for academic research are that it's a tertiary source, and there's no credibility/quality assurance.
So, you should make sure that
- If the image contains intellectual content that requires citation, you should cite a primary source for that content.
- The image (including its factual/intellectual content) meets academic standards of quality and accuracy.
Assuming these are satisfied, reusing images from Wikimedia (or a similar source) is not inherently unprofessional. Of course, if the image is of poor quality or doesn't fit in well with your poster, it will look unprofessional - but this would also be true if you had created the image yourself.
This is, of course, assuming that the image you are using is in Wikimedia commons (not all images on Wikipedia are), and
- you follow the license requirements (protects against legal/copyright problems)
- you correctly attribute the source (protects against ethical/plagiarism concerns)
Adding some details to the previous response, I'd like to stress that many Wikipedia images come from Wikimedia Commons, and Commons is a different project than Wikipedia. It is mainly a repository of free multimedia files
"that makes available public domain and freely-licensed educational media >content to all, and that acts as a common repository for the various projects of >the Wikimedia Foundation." The expression "educational" is to be understood >according to its broad meaning of "providing knowledge; instructional or >informative". [1]
Thus, it is possible to find great images in Commons, that come from various sources (like NASA, or other institutions like museums, galleries, libraries, academic databases, academic journals). There are great pictures on Commons.
Now, you are talking about "simple graphic", and the specific image is "meant to illustrate a basic mathematical notion". [2] There are many professionals who use their free time to provide Commons (and hence Wikipedia articles) with illustrative, clear graphics.
I can't think of no valid reason not to use a graphic meant to illustrate the exact concept you want to illustrate, and meant to be used and shared for free, just because there would be the word "wikimedia" in the credits.
If the images suits your need and you feel it professional enough, please use it and give credit.
[1] https://en.wikipedia.org/wiki/Wikimedia_Commons#Policies
[2] Here's the Mathematics category.
Full disclosure: I'm a >10 years old volunteer in Wikimedia projects, and I've also been very active in movement roles like being president of a Wikimedia national chapter.
The answers here are excellent, but a few points. (This from the perspective of someone who knows Wikipedia policy and Creative Commons licenses well; I do not claim any special expertise in academic standards that might go above and beyond the legal requirements, though.)
The Wikipedia page or the Wikimedia Commons page will almost always have detailed information about the file's license, about its author, and about its origin. You should consult that information as a starting point, and can have a fairly high degree of confidence in its accuracy -- but to meet an academic, professional, or legal standard, you should also find ways to confirm this information for yourself. The information is intended to be helpful in that effort, but is not necessarily authoritative.
When doing that verification, be aware that some of Wikipedia's sources -- including U.S. federal agencies and major museums -- provide deceptive or incomplete information. In a comment thread above, it's been noted that images in the public domain may be marked with "licenses" or other text that indicates they are only to be used for non-profit purposes, or they are not to be modified, etc. Sadly, such cases are not uncommon. Those claims are inaccurate. If a file is truly in the public domain, no such requirement can be legally binding. (If you're in such a situation and it's important, you should check with a lawyer.)
Many (but not all) files will require attribution (the "BY" component of CC BY or CC BY-SA licenses). However, that attribution is to the copyright owner, not to Wikipedia or Wikimedia. As a practical matter, Wikimedia's Terms of Use suggest a link to the Wikimedia page as the minimal/standard way to fulfill that attribution (which is important in the case of anonymous/pseudonymous contributors, whose Wikimedia avatar is the only available method of attribution). But in many cases, a user provides their legal name; and in some, they even indicate a preference for how to write the attribution, perhaps including a business name (as I have done here, for example). If for some reason you prefer not to credit "Wikipedia" or "Wikimedia", that may be just fine. Look closely. Also, beware of the (thankfully rare) files you may find on Wikimedia Commons that are available under only the GFDL license; its attribution requirements are highly arcane and cumbersome!
The "Share-Alike" (SA) component of a license commonly used on Wikimedia has not been discussed. It's rare that it would impact a project like this, but it could. If your poster is derived from a file with such a license (which is a different standard than merely including it), then your poster must be made available with the same license.
Disclosure was brought up in a comment thread above, so a few points about myself:
- I'm not a lawyer
- I'm one of many co-authors of the Wikimedia/Wikipedia Terms of Use
- I run a training & consulting company focused on Wikipedia
- I'm the editor of the Wikipedia Signpost newsletter.