Science & Engineering Research Support soCiety (SERSC)
In this paper, a novel scheme is proposed for watermarking lossy compressed images just before transmission and authenticating them once they are received, away from the core of the compression and de-compression processes. The scheme is inserted into the Joint Photographic Expert Group (JPEG) structure that is encoded using the Discrete Cosine Transform (DCT) at specified locations. The watermark information is extracted from and embedded into specified DCT coefficients, following novel criteria. The scheme is robust to lossy compression; though it is fragile, exposing any slight changes of the probe images.