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An Adaptive Robust Digital Image Watermark Based on the Discrete Operation

An adaptive robust watermarking algorithm in which a binary character watermark was embedded into the grayscale digital image based on the discrete operation was proposed. The approximation subband of the original digital image in the wavelet domain was decomposed into blocks and classified first by considering human visual masking characteristics. Then, the blocks with best abundant texture information were selected adaptively according to the size of binary character watermark, and the watermark embedding was carried out by adjusting these selected block coefficients based on the discrete operation. A scheme is also developed for watermark extraction from the distorted image based on the discrete operation. As the watermark embedding and extraction are based on the binary discrete operation, the embedded digital watermark with the proposed algorithm is robust enough against the commonly used image processing such as additive noise, filtering, JPEG compression, and geometric cropping.