Wikipedia:Scanning an image does not make it your "own work"
People often upload images to Wikipedia and to the Wikimedia Commons – photographs, works of art, posters, etc. – and claim them as their "own work" and often themselves as the "author", under the idea that scanning an image they found somewhere, taking a screenshot, photographing an already copyrighted work, and/or the act of uploading itself, confers upon them the status of owner. With some exceptions noted below, it does not.
As an illustration of the logical flaw inherent in thinking these acts make you an image's owner, consider this: If you were to take a book off your shelf and manually re-type it, would that make you its author and the owner of its copyright? Of course not.
Nevertheless, many users, laboring under this misunderstanding, purport to release the copyright of such images, uploaded as their "own work", when they were never theirs to begin with.
As a simple example of valid ownership, you are the owner of an (original) painting that you painted (or inherited from the painter). Photographs can be less straightforward. As a general rule (and outside of legal inheritance of photographs) you are not the owner of a photograph unless you took the photograph with your camera, or paid for it to be taken in a work for hire relationship. But that is only the first step in analysis, because, taking a simple photograph of something that is already copyrighted, creates no ownership in you. For example, if you snap a flat photograph of a poster, you have done nothing original and you do not own the copyright to that image.
It becomes more complicated where the manner of your photograph results in significant original transformation, modification or adaptation of the already copyrighted image you photographed. When that is the case, a secondary copyright may be created, called a derivative work. Nevertheless, that part of the picture depicting the existing copyrighted work, retains its copyright. This means, in turn, that you cannot release that image unless you also own the original work. Note that original photographs that contain only a very insignificant part of an already copyrighted work may meet a "de minimis" exception to copyright.
Please do not claim ownership of other people's work as your own and then attempt to release an image's copyright over which you have no authority. Doing so is copyright infringement.