A high-efficiency blind watermarking algorithm for double color image using Walsh Hadamard transform

This paper presents an efficient blind watermarking algorithm for double color images using Walsh Hadamard transform (WHT). In this algorithm, the energy gathering function of WHT and the strong correlation between the matrix coefficients in the frequency domain after transformation is used for embedding the digital watermark. Firstly, the color host image is divided into R, G, and B channels, and each channel is partitioned into 4 × 4 blocks. By researching the frequency domain coefficients of the WHT blocks, a strong correlation can be found between the coefficients of the first row of the frequency domain matrix, especially the first and second elements and the third and fourth elements in the first row. Therefore, the digital watermark can be embedded into the above matrix block by fine-tuning the mentioned coefficients, and the watermark information can be extracted by the difference between the two coefficients. According to a huge number of simulation results, the proposed algorithm shows better performance not only in invisibility but also in robustness, watermark capacity, and running time.