How To Prevent Digital Watermarking

CHAPTER 1 INTRODUCTION

In the early 1990’s, the huge popularity of the World Wide Web revealed the commercial potential of present multimedia resources through the digital networks. With the quick spread of computer networks and the further development of multimedia technologies, they seek to use the digital networks to offer digital media for protection of ownership rights on digital audio, image, and video data. Nowadays this becomes most serious problem because digital copies can be made easily that is identical to the original. So to prevent the data, digital watermarking has been proposed as one way to accomplish this task that provides an imperceptible method to prevent copyright infringement and allow the owner to have solid

Since this digital signal or pattern is embed in each unmodified copy of the original image, the digital watermark may also serve as a digital signature for the copies. A given watermark may be unique to each copy (e.g. to identify the intended recipient), or be common to multiple copies (e.g. to identify the document source). Digital watermarking is changing an image in such a way so that we can see watermarked image without actually corrupting the original image. In some case, digital watermarking involves the alteration of the original into another form. Digital watermarking leaves original digital media (i.e.; image, audio, video, or file) basically intact and recognizable. An effective digital watermark should be invisible to protect the original image. It should be statistically invisible to prevent detection, and it should also be robust to many image manipulations, such as filtering, additive noise, and JEPG

Need of Watermarking

For following applications, [11][12] we used digital watermarking: -

• Ownership assertion: - Watermarking is used to establish ownership over the data.

• Authentication and integrity verification: - Data which is protected by key verification should not be accessible without authentication.

• Usage control: - To limit copies creation of copyrighted data, by blocking using watermark.

• Content labeling: - Bits embedded in data giving extra information.

1.4. Problem Background

Imperceptible watermark means that the watermarked data is perceptually indistinguishable to the original data since human eyes cannot differentiate between the watermarked image and the original image. Use Slantlet Transform (DST) and Wavelet Transform to achieve the proposed methods yields high capacity, good imperceptibility and low bit error rate.

A watermark must be embedded in the host image without causing any kind of degradation to prove the quality of watermarking. Robustness means the ability to recover the watermark after performing various attacks on watermarked image. These attacks include Gaussian noise, cropping, rotation, scaling and JPEG compression and set removal attack and after that evaluating the quality of the watermark without degrading the image. For these attacks, it is possible to identify, detect, modify or remove the watermark from the watermarked image and then used for their own purpose. Hence, it is necessary to prevent