A New Robust Watermarking Scheme Based on Wavelet Transform

A new robust watermarking scheme based on discrete wavelet transform(DWT) is proposed. The proposed scheme embeds a watermark into a host image twice in two different frequency ranges to withstand different type of image processing operations or even deliberate attacks. The host image will be decomposed to different frequencies in different resolution levels by DWT, and then the watermark is embedded into lower frequency coefficients of the host image first, while guaranteeing each two embedded values of the watermark are not adjacent respectively, which should be robust to typical operations such as low-pass filtering and lossy compression. The same watermark, using the spread spectrum technology, is embedded into the mid-frequency coefficients of the host image again to enhance robustness of the watermark. Experimental evaluations show that after the embedded images had been changed by common image processing operations, proposed method has more robustness comparing with existing schemes.