Watermark embedding based on statistical specification of wavelet coefficients in subbands

Many watermarking methods use correlation detection for extraction of watermark. The decision threshold of correlation is chosen based on error probability appeared in detection process. Attacks on watermarked image usually cause fluctuation in error probability, precision, extracted energy, and length. In this paper, we have defined an index referred to as the ´ratio of detection´ constructed from the correlation of coefficients of the stego image with the watermark. It is shown that this factor models the effect of energy and length of watermark and has better performance from decision threshold after any attack. The new algorithm can address fairly good optimization on the above issues. The extracted results are used in a novel embedding approach in which the DWT-coefficients of the image, in each sub-band, are separated into dominant and non-dominant groups. A sequence of a random generator output, referred to as signature data, is then embedded into these coefficients to obtain the watermarked image. Experimental results demonstrate that the proposed method has better robustness compared to other similar methods