Abstract
Printer identification based on a printed document can
provide forensic information to protect copyright and verify
authenticity. In addition to intrinsic features (intrinsic
signatures) of the printer, modulating the printing process
to embed specific signature (extrinsic signatures) will
further extend the encoding capacity. Some features
generated by modulating EP process such like raggedness
of the edge in the text, can be designed and utilized to help
develop the extrinsic signature. By increasing the level of
modulation, which increase reliability of detection and thus
capacity, we can drive the extrinsic signature to a point
without perceptual degradation of the image quality. In this
paper, we will investigate embedding extrinsic signature in
text documents using laser intensity as a signal modulation
source and develop extrinsic signatures using both
frequency as well as amplitude modulation. Preliminary
experimental results showed that it is feasible to embed
detectable extrinsic signatures in text characters without
degrading perceptual text quality.
