The Optimal Hiding Site with DCT

Abstract

Digital Watermarking techniques have been proposed to solve the problem of multimedia authentication and copyright protection; image is one of the important media that need to be secure and authenticated. In this paper, the lossless digital watermarking scheme is proposed, it compare between the results that appear after embedding stage by utilizing the properties of Discrete Cosine Transform (DCT) domain with digital watermarking between low frequency domain and middle frequency domain after embedding stage . The proposed method used different blocking size to hide the logo bit inside the middle frequency domain and low frequency domain after DCT applied for each block of the whole transformed image to find the optimal domain, we take into consideration image color space and texture to evaluate the objective quality for the proposed method and its ability to survive different types of attack (intended and unintended attack). The embedding stage is based on changing the value for the selected DCT coefficients of the host image. We depended on the objective quality to find the optimal blocking size that can used with DCT and assurance intended alternation localization to find the optimal hiding site with optimal domain. The method was tested under different attacks and it was found to provide good objective quality with standard blocking size 8 x 8, 16 x 16, and it was found that it provided good alternation localization with the site of low frequency domain (2 x 2 block size), the middle frequency domain is the optimal with embedding process while maintaining the quality of the watermarked image.