Grayscale image embedding method using spatial-frequency quantization and Peano transposition

In this paper, we present a novel and effective grayscale image embedding method. Different from most of the existing watermarking methods and based on a multi-resolution transformation of an embedded image, the new image embedding method utilizes spatial-frequency quantization and Peano transposition for watermark generation. Spatial-frequency quantization is applied to the wavelet signal of an embedded grayscale image resulting in a uniform signal amplitude in the wavelet transform domain with the low frequency's energy preserved. The property of self-similarity across different levels of multiresolution decomposition, allows us to use a Peano transposition with a Peano mixing map to generate uniformly mixed watermarks. The corresponding multi-strength embedding method is also given. Experimental results show that our watermarking method is feasible, rational and robust to common image signal processing attacks. In addition, it exhibits excellent perceptual transparency.