A Novel Dual Color Image Watermarking Algorithm Using Walsh–Hadamard Transform with Difference-Based Embedding Positions

Image watermarking is an essential technique for protecting the copyright of digital images. This paper proposes a novel color image watermarking algorithm based on the Walsh–Hadamard Transform (WHT). By analyzing the differences among WHT coefficients, an asymmetric embedding position selection strategy is designed to enhance the robustness of the algorithm. Specifically, the color image is first separated into red (R), green (G), and blue (B) channels, each of which is divided into non-overlapping 4 × 4 blocks. Then, suitable embedding regions are selected based on the entropy of each block. Finally, the optimal embedding positions are determined by comparing the differences between WHT coefficient pairs. To ensure watermark security, the watermark is encrypted using Logistic chaotic map prior to embedding. During the extraction phase, the watermark is recovered using the chaotic key and the pre-stored embedding position information. Extensive simulation experiments are conducted to evaluate the effectiveness of the proposed algorithm. The comparative results demonstrate that the proposed method maintains high imperceptibility while exhibiting superior robustness against various attacks, outperforming existing state-of-the-art approaches in overall performance.