01. Innovative Techniques In Digital Water Marking

INNOVATIVE TECHNIQUES IN DIGITAL WATERMARKING

BY

C.RAGHAVENDRA

S.V.JAGADEESH

III CSE, RGMCET,

III CSE, RGMCET,

NANDYAL.

NANDYAL.

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DIGITALWATER MARK

ABSTRACT

The technique of watermarking paper (rather than heads) is almost as old as paper manufacturing itself, dating back to the late middle ages. Their earliest use seems to have been to record the manufacturer’s trademark on the product so that the authenticity could be clearly established without degrading the aesthetics and utility of the stock. Experience with watermarks was so successful, that governments began to watermark their currencies, postage stamps, revenue stamps, etc. to thwart counterfeiting.

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Watermarking is the process of embedding the code in to the multimedia object such that the watermark can be extracted later to make an assertion of about the object. The code can be audio, video or textual data. The code contains the information about the right owner of the object. This paper highlights the difference between stenography, encryption and watermarking. And also simple technique on water marking are proposed and implemented.

1.Introduction In the Middle Ages, kings, dukes, barons, and anyone else

who styled themselves important would carve a design onto a stamp or a ring. This was used to impress a wax or lead closure sealing the wrappings of items sent by courier, ostensibly proving that the document or package did indeed come from them and hence could be considered authentic. cryptographic secret key, inhibiting anybody that does not possess the secret key from reading or even detecting the watermark.The idea is to ensure the Watermarking is a method of protecting digital material. The digital watermarking system is based on that a code is embedded in the image. The code can include various types of information for example ownership of the image, right to copy and terminal identification (a

specific number for each user the image has

been distributed to). The code is digitized, encoded as additional noise and incorporated in the picture. The size of the encoded information has to be kept to a minimum of bits to minimize

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noise. Every member has an unique code that works as an index to the register. This code is encoded into the image. 2 Different ways of providing security The security for the data, transmitting through high speed data networks can be provided in 4 different ways as follows (a) Cryptography: It is the process of disguising a message in such a way as to hide its substance by using keys. i.e. the message which is to be sent through the network is encoded using cryptographic algorithm, the resulting text is called cipher text. This is transmitted through the network. At the receiving end the cipher text is decoded and the original text is obtained. In this the security is entirely dependent on cryptographic algorithm. (b) Steganography: It is the process of hiding secrete message inside another message, such that the very existence of secrete is concealed. Generally the sender writes an innocuous message and then conceals a secrete message on the same piece of paper. Historical tricks include invisible inks, tiny pin punctures on selected characters, minute differences between handwritten characters, pencil marks on type written characters, grilles which cover most of the message except for a few characters, and so on.

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© Time stamping: It is the process of adding time to the data without regard to the physical medium on which it resides. With the help of time we can identify the right owner of the intellectual property. (d) Watermarking: It is the process of embedding the code into multimedia object.

2.1 Types of watermarks There are different varieties of watermarks are available depending on different factors under consideration, one of such factor is visibility. Depending on visibility watermarks are classified as 2.2.1 Visible watermarks A visible watermark is a visible translucent image which is overlaid on the primary image. Perhaps consisting of the logo or seal of the organization which holds the rights to the primary image, it allows the primary image to be viewed, but still marks it clearly as the property of the owning organization. It is important to overlay the watermark in a way which makes it difficult to remove. An example shows both a watermark and an image with the watermark overlaid. 2.2.2 Invisible watermarks

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An invisible watermark is an overlaid image which cannot be seen, but which can be detected algorithmically. Different applications of this technology call for two very different types of invisible watermarks: (i) A watermark which is destroyed when the image is manipulated digitally in any way may be useful in proving authenticity of an image. If the watermark is still intact, then the image has not been "doctored." If the watermark has been destroyed, then the image has been tampered with. Such a technology might be important, for example, in admitting digital images as evidence in court. (ii) An invisible watermark which is very resistant to destruction under any image manipulation might be useful in verifying ownership of an image suspected of misappropriation. Digital detection of the watermark would indicate the source of the image. 2.2 Properties of watermark (i) Unobtrusive: The watermark should be perceptually invisible, or its presence should not interfere with the object being protected. (ii) Robust: The watermark must be difficult (hopefully impossible) to remove. If only partial knowledge is available (for example, the exact location of the watermark in an image is

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unknown) then attempts to remove or destroy a watermark, should result in severe degradation in fidelity before the watermark is lost. In particular, the watermark should be robust to : (a) Common signal processing: The watermark should still be retrievable even if common signal processing operations are applied to the data. These include, digital to analog and analog to digital conversion, resampling, requantization (including dithering and recompression), and common signal enhancements to image contrast and color, or audio bass and treble, for example. (b) Common geometric distortions (image and video data): Watermarks in image and video data should also be immune from geometric image operations such as rotation, translation, cropping and scaling. © Subterfuge Attacks: Collusion and Forgery In addition, the watermark should be robust to collusion by multiple individuals who each possess a watermarked copy of the data. That is, the watermark should be robust to combining copies of the same data set to destroy the watermarks. Further, if a digital watermark is to be used in litigation, it must be impossible for colluders to combine their images to generate a different valid watermark with the intention of framing a third party.

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(iii) Universal: The same digital watermarking algorithm should apply to all three media under consideration. This is potentially helpful in the watermarking of multimedia products. Also, this feature is conducive to implementation of audio and image/video watermarking algorithms on common hardware. (iv) Unambiguous: Retrieval of the watermark should unambiguously identify the owner. Furthermore, the accuracy of owner identification should degrade gracefully in the face of attack. 3.Methodology 3.1 Fragile invisible watermark technique As we know a digital image can be considered to be a two dimensional array of values or sampled image intensities in the form of gray levels. Each gray level is quantized or assigned one of finite set of numbers represented by fixed number of bits, for monochrome gray level image it is 8-bits. Each pixel gray level value stored in these 8-bits, but as we know the LSB of each pixel contains least information of the image gray level because after all it can effect the gray level value by an amount 1. Hence by making all these LSB’s to zero in each pixel value, the human visual system can’t find the difference to this image and original image. Hence, we can use these LSB”s to hide our watermark or copy right information in the LSB’s of image pixels. The process is explained as follows…

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a) read the ASCII value of the first character in the message or watermark (ASCII character contains 8-bits) b) place the 1-MSB bit of message/image in the LSB position

of 1st pixel, and next 2-MSB bit in the LSB position of next pixel, ….and so on until all 8-bits of first ASCII value of the message/watermark is placed in the successive 8pixels LSB’s positions. c) Read the next ASCII value in the message/watermark and repeat steps (a) and (b) d) Repeat all the above steps until all the ASCII values are covered in the given message/watermark file When all the above steps are finished we can obtained the watermarked image, we can’t find the difference between original image (Un-watermarked image) and watermarked image. 3.2 Results: (a)

Images with copy right information hidden in it shown below along with it original image

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Original Image

Watermarked Image

Message Hidden:- This property is copy righted to Mr. RAO’s company, illegal use of this photograph in any manner is considered to be a crime…..!

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Original Image

Watermarked Image

Message Hidden:- This property is copy righted to Mr. RAO’s company, illegal use of this photograph in any manner is considered to be a crime…..!

(B) The images watermarked with a logo image are shown below

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LOGO Image

Original Image

Watermarked Image with Logo

3.3 Advantages and Disadvantages Advantages: (i)

It is simple than all other time domain methods

(ii)

It can also be used for authentication purpose

(iii)

It can also be used for integrity checking

(iv)

It can also run efficiently on small processors

Disadvantages:

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(i)

If all LSB’s are set to zero in the Image file we can’t prove copy rights hence it is simple to erase the watermark from object being protected.

(ii)

If a attacker modifies some important content of image and then sets the all LSB’s of image pixels to zero, it can’t detect the integrity of the content, authenticity also not clear in this type of attack.

3.4 Further extensions (i)

The message/watermark i.e the copy rights can be can be encrypted using cryptographic algorithms and then it can be placed in LSB’s of image pixels, this provides a greater security to the watermark stored in the image.

(ii)

Rather than starting the insertions of message bits from first pixel onwards in the image file, start the insertion from any pixel in the image file. Here the starting position of pixel in the image file is kept as secrete.

(iii)

You

can

also

use

any

random

number

generator

algorithm and insert the bits in the LSB of pixels as pixel position is given by random number generator in the image file. The algorithm should be kept as secrete here.

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REFERENCES

1) R.L Lagendijk, G.C. Langelaar, and I. Setyawan, “Watermarking digital image and video data,” IEEE Signal Processing Mag., Vol. 17, pp. 20-46, Setp. 2000. 2) F.Hartung and M.Kutter, “Multimedia water marking techniques”, Proc. IEEE, vol.87, pp 1079-1107, July 2004 3) M.Yeung and F.Mintzer, “An invisible watermarking technique for image verification,” in Proc. IEEE Int. Conf. Image Processing, Santa Barbara, CA, Oct. 2002, pp 680683. 4) P.W. Wong, “A public key watermark for image verification and authentication”, in Proc. IEEE Int. Conf. Image Processing, Chicago, II, October 4-7, 2001, pp 425-429. 5) J.fridrichm M.Goljan, and A.C. Baldoza, “New fragile authentication watermark for images, “in Proc. IEEE Int. Conf. Image Processing, Vancouver, BC, Cannada, Sept. 1013, 2000.

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