DCT watermarking Speaker: Paul 1

Outline Introduction DCT watermarking Demo Conclusion Reference 2

Introduction Digital watermark was first coined in 1992 by Andrew Tirkel and Charles Osborne. Digital watermark is a kind of marker covertly embedded in a noise-tolerant signal such as audio or image data. 3

Introduction(cont.) DCT is short for Discrete Cosine Transform Like the discrete Fourier transform, a DCT operates on a function at a finite number of discrete data points. 4

DCT watermarking 5

DCT watermarking(cont.) Slicing the picture into 8x8 block, and minus 128 DCT formula 6

DCT watermarking(cont.) Quantization: Using default JPEG quantization table Randomly choose hiding block from middle frequency 7

Demo 8

Conclusion DCT watermarking could prevent the data form illegally embezzled. Using DCT watermarking can have fidelity preservation, robustness to common signal and geometric processing operations, robustness to attack, and applicability to audio, image and video data. 9

Reference I. J. Cox, J. Kilian, F. T. Leighton, and T. Shamoon, “Secure spread spectrum watermarking for multimedia,” IEEE Trans.Image Processing, vol.6, pp.1673-1687, 1997. Eckhard Koch and Jian Zhao, “Towards robust and hidden image copyright labeling,” in IEEE international Workshop on Nonlinear Signal and Image Processing, pp.452-455, Marmaras, Greece, Jun. 1995. Discrete Cosing Transform Tutorial 10