An Efficient Image Watermarking Method using Lifting Wavelet Transformation (LWT)

In image watermarking method we have two common attacks namely, Cropping and random bending. In this paper we propose a method of image-watermarking to deal with these attacks, also with other common attacks. In the embedding process, the pre-processing of host image is done by a Gaussian low-pass filter and then, we select randomly a number of gray levels and the histogram of the filtered image is constructed and these methods are also followed for secret key image . After that, a histogram-shape-related index is given to choose the pixel groups with the highest number of pixels and a safe band is given between the chosen and non-chosen pixel groups. A watermark-embedding scheme is determined to insert watermarks into the chosen pixel groups. The histogram-shape-related index and safe band are used to bring about good robustness. Moreover, a high-frequency component modification mechanism is also applied in the embedding scheme to further improve robustness. At the decoding end, based on the assigned secret key, the watermarked pixel groups are discovered and watermarks are extracted from them.