A Multiple and Mixed Watermark in Digital Image Based on DWT
Xiaodong Zhu · Jisuanji fangzhen · 2005
Toward the distributing feature of DWT coefficients, on the foundation of lots of researches and experiments on the watermark embedding methods in low, intermediate, high frequency of DWT domain, we design a watermark scheme to embed multiple, mixed watermark in digital image based on DWT. In the low frequency coefficients of DWT, we embed the m-sequence as the watermark information into the digital image by using spread spectrum; At the same time, in the intermediate and high frequency, we embed a real pseudo-random sequence which meets N(0,1) distribution into the image. And each watermark has the property of blind extraction. From the results of experiments, this multiple and mixed watermark method uses several properties of watermark in each frequency. Comparing to single watermark method, our scheme enhances the robustness on the condition of transparence.