An Angle QIM Watermarking Algorithm Based on Watson Perceptual Model

In this paper, a new angle quantization index modulation (Angle QIM) watermarking algorithm is proposed. Instead of embedding information by quantizing the amplitude of pixel values, Angle QIM works by quantizing the angle formed by the host- signal vector. The proposed method is based on modifying the low-mid frequency DCT coefficients imperceptibly to quantizing the angle formed by the host-signal vector. During the modulation, a theorem deduced from Watson's perceptual model is employed to restrict the modified magnitude of coefficients. Experimental results indicate that the presented watermarking method performs well in both security and robustness.