1. Watermarking Matt Elliott Brian Schuette

2. Overview Goals Methods Comparison Attacks References

3. Goals Watermark Goals Robust Invisible Recovery Project Goals Watermark Types –Fragile –Robust Techniques –Frequency Domain –Spatial domain

4. Bit-Plane Slicing Spatial Domain LSB contains watermark Simple detection Many options –Image blocks –Encode Text –Specific Areas

5. Cox Method –Frequency Domain –Transformation –AC Coefficients Sorted by size Largest 1000 selected Psuedo-random watermark embedded –Reverse transformation 2D DCTsort v’=v (1+  w) IDCT & normalize Original image N largest coeff. other coeff. marked image random vector generator wmk seed

6. Comparison Fragile Watermark –Very susceptible to attack –Used for tampering detection Robust Watermark –Resistant to tampering –Used with public images –Provides proof of ownership

7. Bit-Plane Slicing

8. Methods of Attack Scaling Cropping JPEG Print/Xerox

9. References ECE 738 Advanced Digital Image Processing Professor Hu Wikipedia Digital Image Processing, Gonzalez and Woods I. Cox, J. Kilian, T. Leighton, T. Shamoon: “Secure Spread Spectrum Watermarking for Multimedia'', IEEE Transaction on Image Processing, vol.6, no.12, pp.1673-1687, 1997.

10. Questions?