A blind watermarking algorithm based on specific component quantization in DHT domain

For meeting the higher demands of color image ownership protection in the fifth-generation (5 G) communication network, a blind watermarking algorithm based on specific component quantization of discrete Hartley transform (DHT) is proposed. At first, the color cover image is partitioned into the non-overlapping blocks of sized 4 × 4, and the DHT component of the selected block at specific location is calculated; then the inherent correlation in RGB channels and quantization index modulation (QIM) technique are used to obtain the component difference; finally, without global DHT of forward and inverse, the color watermark logo is inserted into the cover image by the derived modification method. Moreover, RSA public-key encryption algorithm is applied to scramble the parameters of Affine transform, which guarantees the double-layer security of watermark itself and algorithm secret keys. When extracting watermark, an image correction strategy based on geometric features is realized to resist geometric distortion. Experiment results show that the proposed algorithm has low computational complexity, strong robustness and high security at the foundation of good invisibility and large payload, which overcomes the shortcoming of slow execution speed of transform-domain watermarking and has high feasibility of fast copyright protection in 5 G environment.