Countermeasure of re-recording prevention against attack with short wavelength pass filter

A previously proposed method using infrared (IR) rays to prevent the re-recording of images and videos corrupts the recorded content by adding invisible noise signals using a charge-coupled device or CMOS device during recording. However, it is not effective against re-recording using a short wavelength pass filter (SWPF) to eliminate the noise. We have now implemented a countermeasure that makes it effective against re-recording using such filters. It detects IR rays reflected off the filter by using the IR specular reflection properties of the filter. Evaluation of the countermeasure implemented on a functional prototype system showed that it effectively detects re-recording using an SWPF.