Optimal color watermarking scheme using PSO in RDWT domain

The main issues in any watermarking scheme are the robustness and transparency of color images against different manipulations. The watermarked images are generated using a gain factor in many watermarking techniques. But the selection of gain factor is a significant issue in many watermarking techniques developed by manual or trial and error processes. Therefore, the optimization algorithm used for the generation of the optimal gain factor is used to generate watermarked images. The proposed method uses particle swarm optimization (PSO) to create an optimal gain factor. In contrast, a block redundant wavelet transform (RDWT) is used to generate color watermarked images. Here, RDWT is applied to the color cover image to get coefficients of different wavelet subbands. Noise sequences modify the coefficients of detail wavelet subbands of the color cover image in this scheme according to watermark bits. The experimental results and comparative analysis of the scheme with existing schemes show that the proposed scheme performs better in imperceptibility, robustness, and payload capacity.