High accuracy document source detection

A method performed by one or more processors, the method comprising:

• ranking unique copies of a set of unique copies based on a first subset of unique copy keypoints that matches artifact keypoints of an artifact relative to unique copy keypoints within each unique copy;
• determining uniquely matching keypoints for each unique copy, the uniquely matching keypoints comprising a second subset of unique copy keypoints that matches the artifact keypoints for only one of the unique copies in the set of unique copies;
• and
• from the set of unique copies, providing a unique copy from which the artifact was derived based on an absolute match significance of a first-ranked unique copy and a unique match significance determined from the uniquely matching keypoints of the first-ranked unique copy.

One or more computer storage media storing computer-readable instructions thereon that, when executed by a processor, cause the processor to perform a method comprising:

• identifying unique copy keypoints for each unique copy in a set of unique copies;
• identifying artifact keypoints for an artifact derived from one of the unique copies in the set of unique copies;
• ranking the unique copies based on a first subset of unique copy keypoints that matches the artifact keypoints relative to the unique copy keypoints for each unique copy;
• determining uniquely matching keypoints for each unique copy, the uniquely matching keypoints comprising a second subset of unique copy keypoints that matches the artifact keypoints for only one of the unique copies in the set of unique copies;
• and
• outputting an indication identifying whether the artifact was derived from a unique copy, from the set of unique copies, based on an absolute match significance of a first-ranked unique copy and a unique match significance determined from the uniquely matching keypoints of the first-ranked unique copy.