Abstract:

        We present a semifragile nonsubsampled contourlet transform (NSCT) based watermarking algorithm for image authentification. We embed watermark in the singular values (SVs) of the blocks within lowfrequency subbands of NSCT by an adaptive quantization method. Watermark extraction is available only with a key constructed by chaotic signal initial value and quantization parameters. Subbands of individual scale and individual direction all have the same size as those of the original image. This algorithm can improve the tampering localization capability without causing remarkable manmade trace. Experimental results show that this algorithm is robust to JPEG compression but extremely sensitive to malicious operations.

Key words: watermark, authentification, nonsubsampled contourlet transform, single value decomposition