Digital Image Watermarking Framework Using LWT and DCT

Abstract

As a protection against unauthorized copying of digital multimedia objects, digital watermarking technology is now attracting substantial attention. In this paper, an image watermarking algorithm is presented by utilizing a cascade of two powerful mathematical transforms; the Lifting Wavelet Transform (LWT) and the Discrete Cosine Transform (DCT). The lifting wavelet transform is applied to decompose the original image into four subband images. Then the discrete cosine transform is computed on the selected sub-band of the LWT coefficients. The watermark is embedded in the DCT transformed the selected LWT sub-band of the cover image. The proposed system focuses on an invisible watermark embedding and quality factors such as imperceptibility to degradation of watermarked image and performance evaluation metrics. This presented algorithm is realized in MATLAB.