DWT and SVD based image watermarking scheme using noise visibility and contrast sensitivity

This paper presents a robust and imperceptible methodology of watermark embedding in the transform domain using Discrete Wavelet Transform (DWT). The robustness is brought about by hiding the watermark in the Eigen values after computing the Singular Value Decomposition (SVD) on low frequency sub-band after DWT. While for the imperceptibility the Contrast Sensitivity Function (CSF) has been employed here along with the Noise Visibility Function (NVF). Human beings are sensitive to visual contrasts so CSF is used to take care of that while NVF characterizes the local image properties of texture, edge and smoothness to determine the optimal watermark locations and strength at the wavelet sub-bands for watermark embedding. The algorithm has been tested on 16 metrics out of which 10 are for imperceptibility and 6 for robustness for some popular attacks and the result has been found encouraging.