Global Journal of Science Frontier Research Vol. 10 Issue 1 (Ver 1.0), April 2010 Page | 15 GJSFR Classification (FOR) 090301,090302,090605 & 090603 An Improved Scheme for Digital Watermarking Based On Discrete Cosine Transformations Ajay Goel α ,O.P.Sahu Ω , Rupesh Gupta € ,Sheifali Gupta £ Abstract- Digital Watermarking is a technology of embedding watermark with intellectual property rights into images, videos, audios and other multimedia data by a certain algorithm. The basic characteristics of digital watermark are imperceptible, security, reliability, low complexity of watermarking algorithm and security of the hiding place. Digital Watermarking Algorithm is composed of three parts: watermark embedding algorithm, the watermark extraction algorithm and the watermark detection algorithm. Future research of digital watermarking technology will focus on the watermarking algorithm, the study of watermarking theories, the watermark attacks and the evaluation system of watermarking system. A robust digital watermarking approach is proposed using the modified discrete cosine transformation (MDCT). The quality of the watermarked image is high and is robust to compression, noises, filtering and geometric transformations. Keywords- Watermarking Techniques, robustness, DCT, Spread Spectrum Approach, Masking, MDCT, Copyright Protection. I. INTRODUCTION he use of digitally formatted audio, video, and printed information is increasing rapidly with the expansion of multimedia broadcasting, networked databases, electronic publishing, etc. This progressive switch to digital representation of multimedia information (text, video, and audio) provides many advantages, such as easy and inexpensive duplication and distribution of the product. However, it also increases the potential for misuse and theft of such information, and significantly increases the problems associated with enforcing copyrights on multimedia information [5],[1],[2] the protection and enforcement of intellectual property rights has become an important issue in the digital world. Well-established organizations are actively pursuing research into digital watermarking and are calling for proposals to incorporate these methods in current multimedia standards. There are various watermarking schemes applied to images and several methods applied to audio and video streams, among them; a large class of the watermarking schemes addresses About 1 -Department of Computer Science & Engineering, Singhania University, Rajasthan, India About 2 -Department of ECE, N.I.T. Kurukshetra, India, About 3 -Department of ME, Singhania University, Rajasthan, India, About 4 -Department of ECE, Singhania University, Rajasthan, India, invisible watermarks. We are currently in an evaluation phase of the technology in which researcher are developing general guidelines for effective watermarking algorithm design, improving reliability within the constraints of computational complexity and tailoring to the constantly changing needs of multimedia industries [5]. During the past few years, a number of digital watermarking methods have been proposed. The two basic modalities for image watermark encoding are: spatial domain techniques (spatial watermarks) and spatial frequency-domain techniques (spectral watermarks). The following paper describes spatial watermarking algorithms that rely on some type of perceptual knowledge in the encoder. Spatial watermarking techniques provide simple and effective schemes for embedding an invisible watermark into the original image but are not robust to common image alterations. Another way to mark an image is to transform it into the frequency domain- Fourier, DCT, wavelet, etc. - before marking it. The mark is incorporated directly into the transform coefficients of an image. The inverse-transform coefficients form the marked image. These types of algorithms are often called spectral watermarks, and commonly use frequency sensitivity of the human visual system to ensure that the watermark is invisible. Many of these techniques are private watermarks, which require the original image to verify the mark. Algorithms that do not require the original image for testing are called public watermarks [2].Some modified approach are required to perk up the robustness later than the compression of images. II. APPLICATION AREAS 1) Copyright protection: Embedding the ownership of the information when the information is being duplicated or abused. 2) Usage/Copy tracking: Verify the usage and copy of the information by the embedded data. Metadata or additional information: Embedding data to describe the information, e.g., structure, indexing terms, etc. Multiple data embedding: Embedding smaller image in a larger image or multiple audio data in a video. 3) Post-processing of watermarked data: Some watermarked data are required to undergo some lossy signal-processing operations. For examples, images for storage and transmission may perform lossy coding operation in order to reduce bit rates and increase efficiency. T