The take-away is that as the artist/author you own the copyright to your work. Even though you sold someone the original, you still own the rights to that image (unless you've also expressly sold the copyright) and the owner of the original cannot reproduce it without your permission. Read through the site and see if you come to the same conclusion.
Here's what they say:
" Generally, copyright lasts for the life of the author, the remainder of the calendar year in which the author dies, and for 50 years following the end of that calendar year. Therefore, protection will expire on December 31st of the 50th year after the author dies. In the case of a work that has more than one author, the copyright will last for the remainder of the calendar year in which the last author dies, and for 50 years after that."
