In this paper, we use a set-theoretic approach to provide an efficient and deterministic iterative solution for the
compensated signature embedding (CSE) scheme introduced in an earlier work.<sup>4</sup> In CSE, a fragile signature is
derived and embedded into the media using a robust watermarking technique. Since the embedding process leads
to altering the media, the media samples are iteratively adjusted to compensate for the embedding distortion.
Projections Onto Convex Sets (POCS) is an iterative set-theoretic approach known to be deterministic, effective
and has been used in many image processing applications. We propose to use POCS for providing a compensation
mechanism to address the CSE problem. We identify two convex constraint sets defined according to image
fidelity and signature-generation criteria, and use them in a POCS-based CSE image authentication system.
The system utilizes the wavelet transform domain for embedding and compensation. Simulation results are
presented to show that the proposed scheme is efficient and accurate in terms of both achieving high convergence
speed and maintaining image fidelity.