We're using GraphicsMagick in our product. We are not modifying the source in any way. I am wading through the licenses but it's not clear what text we need to include in our about box and what needs to be in our documentation. Is it enough to say "Portions of this software are Copyright (C) 2002 - 2012 GraphicsMagick Group"? Do we need to include notices from any of the libraries (we're using the JPEG, PNG, and TIFF libraries)?
What about our documentation? Do we need to include the complete text of any of the licenses there?
As far as libpng and zlib are concerned, you don't have to say anything. Mentioning these libraries would be nice but it's not required.
Our legal department weighed in on this question. We meet the requirement for including the necessary licenses "in the software" by including the licenses with the software in a file called notices.txt. We also include the licenses in the documentation. Since the requirement to include the licenses is met by including the notices.txt file, we do not have to include any notices in the About box, though I am lobbying to give credit to the GraphicsMagick community by including "Portions of this software are Copyright (C) 2002 - 2013 GraphicsMagick Group" in the About box.