An adaptive digital image watermarking algorithm based on binary discrete operation was proposed in the wavelet transform domain. At first, the wavelet approximation sub-image of the original image was decomposed into blocks and classified by using the human visual masking characteristics. Then, the blocks with best abundant texture information were selected adaptively according to the size of the pseudo-random sequence watermark, and the watermark was embedded by adjusting these block coefficients based on the binary discrete operation. The original image was not required for detecting the watermark. As the watermarking embedding and detection is based on the binary discrete operation, the embedded digital watermark with the proposed algorithm is robust enough against the commonly used image processing techniques. Moreover, the embedding watermark is invisible.