Wikipedia:What is a featured picture?/Examples of technical problems

There is no agreed definition of what constitutes a featured picture. However, Wikipedia featured picture candidates should not display any of the following technical flaws, unless there are strong mitigating reasons, such as historical significance or unique subject matter: see the featured picture criteria page for guidelines, and the WP:WIAFP/example subject matter gallery for examples of notable exceptions.

In practice
Typically, technical problems in nominated images aren't as blatant as they are in the examples above. Here are some real world case studies.