Yarmouk university Hijjawi faculty for engineering technology Computer engineering department Primary Graduation project Document security using watermarking technique Under the supervision of: Eng.hadeel kasaymeh Prepared by: Hussain al-afeef Abd alkareem al-rabbae Saif bni-easa Osama shatnawe Ismael al-sheiab

outlines 1- introduction about document security.. 2- watermarking technique????? 3- watermarking types…. 4- practical application on the pixels in some image… some image… 5- conclusion…

Introduction Powerful signal processing techniques and ease of modification have made the world shift towards digital representation of multimedia signals such as image, audio and video. The rapid growth of Internet is also fuelling this process. The vendors fear to put their multimedia data over the Internet, because there is no way to track the illegal distribution and violation of copyright protection. Watermarking comes into the scenario as a powerful solution to this problem.

What is the DIGITAL WATERMARKING? Digital watermarking is the process of possibly irreversibly embedding information into a digital signal. The signal may be audio, pictures or video. for example, If the signal is copied, then the information is also carried in the copy. It is the process of altering the original data file. Depending on the specific method used, and we will present it later which is called adjusted purpose watermarking technique …

An advantage of the digital watermarking:- Is to detect the images that may contain unauthorized changes and even help in recovering some of the lost data. A disadvantage of digital watermarking:- Is that a subscriber cannot significantly alter some files without sacrificing the quality or utility of the data. This can be true of various files including image data, audio data, and computer code.

Watermark can be divided into tow types: 1-visible watermarking: The information is text or a logo which identifies the owner of the media. 2-invisible watermarking: Information is added as digital data to audio, picture or video, but it cannot be perceived as such (although it is possible to detect the hidden information).

Adjusted purpose (AP) for digital watermarking technique There are two categories in image watermarking according to its embedding domains: Spatial domain:- In spatial domain, we can simply insert a watermark into a host image by changing gray levels of some pixels in the host image. In spatial domain, we can simply insert a watermark into a host image by changing gray levels of some pixels in the host image.Advantage: Simple, easy and fast. Simple, easy and fast. Disadvantage: The inserted information could be easily detected by computer analysis. The inserted information could be easily detected by computer analysis.

Frequency domain:- In frequency domain, we can insert a watermark into coefficients of a transformed image, for example: In frequency domain, we can insert a watermark into coefficients of a transformed image, for example: The Discrete Fourier Transforms (DFT). The Discrete Fourier Transforms (DFT). The Discrete Cosine Transforms (DCT). The Discrete Cosine Transforms (DCT). The Discrete Wavelet Transforms (DWT). The Discrete Wavelet Transforms (DWT).

Advantage: The inserted information is generally difficult to be detected. Disadvantages: We cannot embed large amounts of data in the frequency domain; because quality of the host image will be distorted significantly. The data embedded in coefficients of a transformed image will be somewhat distorted in the transformation from frequency to spatial domain due to conversion from real numbers into integers.

Watermarks can be categorized into two types According to embedding purposes: 1-Robust:- They are usually used for copyright protection to declare the rightful ownership. They are usually used for copyright protection to declare the rightful ownership. 2-Fragile:- For the purpose of authentication, fragile watermarks are adopted to detect any unauthorized modification. For the purpose of authentication, fragile watermarks are adopted to detect any unauthorized modification.

We can adjust the approach of performing watermarking from spatial to frequency domain by adjusting the size of (VSTW) varying sized transform window. Performing of watermarking will become the spatial-domain approach when VSTW = 1×1, and the frequency- domain approach for other sizes. VSTW = 1×1, and the frequency- domain approach for other sizes.

Also we can adjust the purpose of watermarking from fragile to robust by adjusting the value of (QF) quantity factor. The embedded watermarks will become robust if QF is large, and become fragile if QF is 1. The strategies for adjusting VSTW and QF are described later.

The strategies for adjusting VSTW and QF The size of VSTW can determine whether the spatial or frequency domain is adopted. For example, if the size is 1×1, it is equivalent to the spatial-domain approach. If the size is 2×2, 4× 4, or 8 ×8, It belongs to the frequency-domain approach. Note that, the size of VSTW could be arbitrary, not necessarily a square of power of 2.

In principle, fragile watermarks are embedded into LSB, and robust watermarks are into HSB. In order to integrate both watermarks, the quantity factor (QF) is developed based on the spread spectrum. We know that shifting the binary bits of x to left (denoted as shl) or right (denoted as shr) by y bits is equivalent to multiplying or dividing x by 2^y. The position for embedding the watermark can be determined based on the QF as shown in Table bellow. For example, if the watermark is embedded into the fourth bit (i.e., QF = 8) of a pixel, we will divide the pixel value by 8, and then replace the resulting LSB by the watermark. Finally, we multiply the result by 8 to obtain the watermarked value.

Table: The relation between QF and the embedded position of the watermark Int. Binary Embedded watermark Embedded position QF After embedding New int (LSB)

The watermarks should not be embedded into insignificant regions of an image or its spectrum since many signal and geometric processes could affect these components. For robustness, they suggested that watermarks should be embedded into regions with large magnitudes in coefficients of a transformed image. If the watermarks embedded in insignificant regions, the original image will have huge degradations; therefore, the size of embedded watermarks is quite limited In order to enlarging the capacity of watermarks; small size of VSTW is selected.considering robustness the watermark is embedded into the higher significant bits; therefore, by the VSTW, we can determine the size of each sub-image to enlarge the capacity of the Watermarks.

Conclusion:- Digital watermarking has been demonstrated to be very useful in identifying the source, creator, owner, distributor, or authorized consumer of a document or an image. It can be used for tracking the images that were illegally distributed.

There are many purpose-oriented watermarking techniques. For example, robust watermarks are used to withstand malicious attacks, fragile watermarks are applied for ownership authentication. Further examples are the embedding strategies, some in spatial or frequency domain, and some in the combination of both. Further examples are the embedding strategies, some in spatial or frequency domain, and some in the combination of both.

To integrate all of these, we have presented an adjusted-purpose digital watermarking technique that uses two parameters, VSTW and QF, to choose the desired one particular watermarking. Therefore, when users design their own watermarking approaches, they can adopt our technique as a platform to make a suitable adjustment.

Before the end We want to thank our colleagues Good for listening

The end The end