Document Type

Technical Report

Publication Date


Technical Report Number



The 1996 Child Pornography Prevention Act (CPPA) extended the existing federal criminal laws against child pornography to include certain types of "virtual porn". In 2002, the United States Supreme Court found that portions of the CPPA, being overly broad and restrictive, violated First Amendment rights. The Court ruled that images containing an actual minor or portions of a minor are not protected, while computer generated images depicting a fictitious "computer generated" minor are constitutionally protected. In this report I outline various forms of digital tampering, placing them in the context of this recent ruling. I also review computational techniques for detecting doctored and virtual (computer generated) images.