Block-based adaptive image watermarking scheme using Just Noticeable Difference

Digital watermarking has been proposed as a solution to the problem of copyright protection of multimedia files in networked environments. In this paper, a block-based adaptive image watermarking scheme using just noticeable difference (JND) is proposed. The proposed scheme is performed in both pixel domain and discrete cosine transform (DCT) domain. It first divides host image into 8 times 8 blocks. After that, it calculates the capacity of each block to embed information without being perceptible. This capacity can be determined by JND threshold, which is one feature of human visual system (HVS) model and it measures the smallest difference between watermarked and host image that is just detectable for human vision. The DCT coefficients of each block are adaptively modified according to the JND threshold values. Watermarks will be embedded in the modified DCT coefficients. Performance and experimental results of proposed scheme are presented. As expected, high robustness of watermarked images without image quality distortion can be achieved.