Robustness Evaluation of Digital Watermarking Based on Discrete Wavelet Transform

In this paper, we evaluate watermarking methods using Discrete Wavelet Transform (DWT). In order to clarify the difference of robustness of watermarks and the difference of image quality when decomposition level 1 and 2 of DWT are used, we perform experiments. In the experiments, we embed the digital watermarks in the frequency domain of still images. Then, we evaluate the degradation in image quality caused by the insertion of a watermark. We also evaluate the robustness of the watermark against several attacks (scale, index color, gradation conversion, and frequency conversion) with the evaluation support system JEWELS. Experimental results are summarized in regard to the PSNR value of each watermarked image and the bit error of the watermark extracted from attacked images.