An improved blind watermarking scheme for color image copyright protection using Hahn moments

Ensuring copyright protection against illegal attacks and image processing operations while maintaining blind detection capabilities presents a significant challenge in color image watermarking. To address this issue, in this article, we propose a blind watermarking approach that integrates the Arnold transformation with watermark embedding in the transformed domain. Modified forms of Hahn discrete moments are introduced to effectively extract the key image features within this domain. The watermark is encrypted before being embedded into the magnitudes of the Hahn moments for each block using dither modulation, ensuring robustness against different types of attacks. Additionally, a reconstruction algorithm for color images based on Hahn moments is developed and employed during the watermark extraction phase. Experimental results confirm that the proposed scheme achieves high efficiency in terms of both imperceptibility and robustness. Extensive evaluations demonstrate its superior performance, with its PSNR and SSIM values reaching 64.693 dB and 0.9998, respectively. In the no-attack scenario, a perfect-quality watermark is extracted with BER = 0 and NCC = 1. Under various attacks, including filtering, noise, geometric, and robustness attacks, the proposed scheme continues to extract high-quality watermarks, achieving an average BER of 0.00001 and NCC of 0.9998, thereby outperforming the existing image watermarking techniques.