User blog comment:Semanticdrifter/The CC-BY-SA License and You/@comment-954127-20120717222227/@comment-4811793-20120718174820

@Randomtime, that is a good way of explaining it. Here's a relevant passage from our Licensing Policy:

"Freely licensed or public domain images are strongly preferred on Wikia.

Non-text media on Wikia should not be assumed to be available under the same license as the text. Please view the media description page for details about the license of any specific media file.

If you are uploading files to Wikia, you should cite the source of the file, attribute the authors, and note any copyright information, where applicable. Individual communities may elaborate upon and refine requirements for file uploads."

Most images, like the screencaps you use, are likely to qualify under fair use. When you have altered the images, things do get a little trickier. You are licensing your collages under the CC-BY-SA, but only the specific arrangement you have created. the underlying images are still the property of the copyright holder.