1. Digital Watermarking -Interim Report (EE5359: Multimedia processing) Under the Guidance of Dr. K. R. Rao Submitted by: Ehsan Syed 1000671971 seaquadri@gmail.com The University of Texas at Arlington – Spring 2011

2. Introduction Digital watermarking is based on the science of steganography [1] or data hiding. Steganography comes from the Greek meaning ‘covered writing’. Steganography is defined as the practice of undetectably altering a work to embed a secret message. It is an area of research of communicating in a hidden manner.

3. Introduction.. Steganography and watermarking rely on imperfections of human senses. The human eye has a limited dynamic range so low quality images can be hidden within high quality images [2].

4. Basic Principle There are three main stages in the watermarking process [3]: generation and embedding attacks retrieval/detection

5. Generation and Embedding Generation of watermarks is an important stage of the process. Watermarks contain information that must be unique otherwise the owner cannot be uniquely identified. In embedding, an algorithm accepts the host and the data to be embedded and produces a watermarked signal. Various algorithms have been developed so far [4-13].

6. Attacks The watermarked signal is then transmitted or stored, usually transmitted to another person If this person makes a modification, this is called an attack. There are many possible attacks.

7. Retrieval/Detection Detection is an algorithm which is applied to the attacked signal to attempt to extract the watermark from it. If the signal was not modified during transmission, then the watermark is still present and it can be extracted.

8. Block diagram Fig.1: Basic block diagram of digital watermarking

9. Types of watermarking There are mainly three types of watermarking [14]: Visible watermarking Invisible watermarking Dual watermarking

10. Techniques of watermarking There are two major techniques of watermarking [15]: Spatial domain: slightly modifies the pixels of one or two randomly selected subsets of an image Frequency domain: this technique is also called transform domain. Values of certain frequencies are altered from their original.

11. Project Goals The goals of this project are: to embed a watermark into an image using LSB technique compressing the watermarked image decompressing it extract the watermark from the image

12. Program for making watermarked images host_image = input('Enter the host image file name with extension : ', 's') ; wmrk_image = input('Enter watermark image file name with extension: ', 's'); host = imread(host_image); wmrk = imread(wmrk_image); figure(1) imshow(host,[]) title('Host Image') figure(2) imshow(wmrk,[]) title('Watermark Image') host=double(host); wmrk=double(wmrk); bits=3; wmrk_shifted=bitshift(wmrk,-(8-bits)); for i=1:bits host=bitset(host,i,0); end watermarked_image = uint8(host+wmrk_shifted); figure(3) imshow(watermarked_image,[]) title('Watermarked Image')

13. Host Image

14. Results so far Watermarked images are created JPEG compression and decompression will be done in the final report Extraction of the watermark from the watermarked image will be done in the final report

15. Watermark Image

16. Visible Watermarked image

17. Invisible Watermarked image

18. References 1.L.M. Marnel et al, “Spread spectrum image steganography”, IEEE Transactions on Image Processing, pp 1075- 1083, Aug 1999 2.J.J.K O-Ruanaidh et al, “Watermarking digital images for copyright protection, IEE Proceedings in Vision”, Image and Signal Processing, pp250-256, Aug 1996 3.I. J. Cox and M. L. Miller, “A review of watermarking and the importance of perceptual modeling”, Proceedings of Electronic Imaging, February 1997 4.H.J. Wang et al, “Wavelet based digital image watermarking “, Optics Express, PP 491-496, Dec 1998 5.P.-T.Yu et al, “ Digital watermarking based on neural networks for color images”, Signal Processing, PP 663-671, Mar 2001 6.J. O-Ruanaidh et al, “Cryptographic copyright protection for digital images based on watermarking techniques”, Theoretical Computer Science, pp 117-142, Sep 1999 7.C. Fornaro and A.Sanna, “Public key watermarking for authentication of CSG models”, Computer-Aided design, pp 727-735, Oct 2000 8.M. Barni et al, “Copyright protection of digital images by embedded unperceivable marks”, Image and Vision Computing, pp897-906, Aug 1998 9.J.R. Hernandez et al, “Improving the performance of spatial watermarking of images using channel coding”, Signal Processing, pp 1261-1279, July 2000 10.S. Pereira et al, “Optimal transform domain watermark embedding via linear programming”, Signal Processing, pp 1251-1260, July 2001 11.F. Perez-Gonzalez et al, “Approaching the capacity limit in image watermarking: a perspective on coding techniques for data hiding applications”, Signal Processing, pp 1215-1238, July 2001 12.R. Baitello et al, “From watermark detection to watermark decoding: a PPM approach”, Signal Processing, pp 1261-1271, July 2001 13.M. Barni et al, “A DCT-domain system for robust image watermarking”, Signal Processing, pp 357-372, May 1998 14.S. P. Mohanty, et al, “A Dual Watermarking Technique for images”, Proceedings of the seventh ACM international conference on Multimedia, pp 49-51, 1999 15.F. Hartung and M. Kutter, “Multimedia watermarking techniques”, Proceedings of the IEEE, Vol. 87, No. 7, pp 1079 – 1107, July 1999