A methodology for comparing robustness of watermarking techniques is proposed. The techniques are first modified into a standard form to make comparison possible. The watermark strength is adjusted for each technique so that a certain perceptual measure of image distortion based on spatial masking is below a predetermined value. Each watermarking technique is further modified into two versions for embedding watermarks consisting of one and 60-bits, respectively. Finally, each detection algorithm is adjusted so that the probability of false detections is below a specified threshold. A family of typical image distortions is selected and parametrized by a distortion parameter. For the one-bit watermark, the robustness with respect to each image distortion is evaluated by increasing the distortion parameter and registering at which value the watermark bit is lost. The bit error rate is used for evaluating the robustness of the 60-bit watermark. The methodology is explained with two frequency-based spread spectrum techniques. The paper is closed with an attempt to introduce a formal definition of robustness.

Date Published: 9 April 1999
PDF: 12 pages
Proc. SPIE 3657, Security and Watermarking of Multimedia Contents, (9 April 1999); doi: 10.1117/12.344671

Published in SPIE Proceedings Vol. 3657:
Security and Watermarking of Multimedia Contents
Ping Wah Wong; Edward J. Delp III, Editor(s)