Hi Pomahony,
Thanks for your kind words.
Your message will be seen quicker if you put it on a user's Discussion page, as opposed to his/her User page. You can think of the Discussion page as a forum for that user, while his/her User page is for him/her to describe himself/herself.
This page explains the legal meaning of "derivative work"; more commonly, it just means that a particular work of art was based on an existing one.
In this case, I created the upper-right graphic based on the bottom-right one by Will Heltsley (according to its summary).
Happy contributing to Wikipedia!