The purpose of this paper is to present an imperceptible and robust watermarking algorithm with high embedding capacity for digital images based on discrete wavelet transform (DWT) domain.
First, the watermark image is scrambled using chaotic sequence and mapped to avoid the block effect after embedding watermark into the host image. Then, the scrambled watermark is inserted in LH2 and HL2 sub‐bands of the DWT of the host image to provide a good tradeoff between the transparency and the robustness of watermarks.
This paper presents experimental results and compares the results to other methods. It can be seen from the comparison that this method can obtain a better performance in many cases.
One of the main differences of this technique, compared to other wavelet watermarking techniques, is in the selection of the wavelet coefficients of the host image. When performing second level of the DWT, most methods in the current literature select the approximation sub‐band (LL2) to insert the watermark. The technique presented in this paper decomposes the image using DWT twice, and then obtains the significant coefficients (LH2 and HL2 sub‐bands) of the host image to insert the watermark.
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