MORPHOLOGICAL IMAGE TAMPER DETECTING METHOD CONSIDERING ROBUSTNESS AGAINST COMPRESSION

摘要

This paper proposes mathematical morphology-based tamper detecting methods that consider robustness against compression. Some operation of mathematical morphology have an algebraic property called idempotence that once an image is processed, it will never be changed by further operation with the same structuring element. The conventional morphology-based tamper detecting method judges a suspected image to have been tampered if idempotence is disrupted between the suspected image and its morphologically operated image. This conventional method, however, has difficulty in distinguishing between malicious tampering and legal compression. This paper shows that idempon-tence holds for compressed images under certain conditions. This property enables the proposed method to distinguish compression from tampering.