Watermarking for Still Images Using a Computation of the Watermark Weighting Factor and the Human Visual System in the DCT Domain

Abstract

In this chapter, the authors propose a Discrete Cosine Transform (DCT)-based watermarking method using the calculation of the watermark weighting factor and the Human Visual System (HVS) for the given peak signal to noise ratio of still image as well as the specified length of watermarks to be inserted. Using the energy relationship of the DCT, they derive the equation that directly computes the watermark weighting factor in the DCT domain. In addition, the authors propose a digital watermarking method for still images, in which the HVS is used in the DCT domain. The modulation transfer function of the HVS model is employed to increase the invisibility of the inserted watermark in images. Experimental results show that the proposed watermarking method is an effective objective evaluation method to compare the performances of watermarking algorithms.