Digital Image Watermarking by Using Discrete Cosine Transform Methodology

Abstract

Watermarking is the process of hiding the digital information in a carrier signal. The digital image watermarking approach for copyright protection is applicable to both RGB and monochrome images. Discrete Cosine Transform (DCT) is used for embedding the watermark in the host image. In the embedding process the luminance component of the host image is divided into 8 × 8 sub-blocks. By correlating the two DCT coefficients embedding can be implemented in DCT domain. Chaotic encryption is used to provide security with speed and efficiency. Arnold transform is used in addition to chaotic encryption to add double-layer security to the watermark. In addition it provides good hidden invisibility to the image and also prevents from several image attacks like joint picture expert group compression, sharpening, cropping and median filtering. The applications are like e-healthcare and telemedicine to robustly hide electronic health records in medical images.