Warning : This document is still a draft
DRAFT - Watermarking, Steganography, and DRM
fragile, robust, semifragile against a specific type of distortion.
Visible or impercetptible.
Digital Watermarking: Algorithm and Application 500 citations. 15 pages
Domains:
- images (largest domain )
- Audio
- Video
- Text
- Document
Hidden signal + Host image + => Composite signal
3 tradeoff: Robustness, Minimization of distortion rate, maximize capacity.
QIM
Images
Algorithms for images:
Spacial VS Spectral domain
- LSB
- DCT Discrete Cosine Transform
- DWT: Discrete Wavelet Transform
LSB: modify bits that are the less visible. Sensible au modification (rotation / compression) Good ratio. 300x300 image 8bit BW: 900,000 bits
Patchwork algorithm
Take two patch, the diff between the patch gives info.
Etalement de spectre
Lin’s algorithm
QIM: Quantization Index Modulation
Probleme:
- rotation
- compression
- stirmark
Add synchronization marker.
Document
- Metadata
- Character moves. Line up or down from small shift, change character size.
Audio
Analog to discrete conversion should be OK
Kerchkoff principle: The algorithm is public. The key is private.
15] I.J. Cox, J. Kilian, T. Leighton, and T. Shamoon, “Secure spread spec- trum watermarking for multimedia,” NEC Research Institute, Princeton, NJ, Technical Report 95-10, 1995
[16] I. Cox, J. Kilian, T. Leighton, and T. Shamoon, “Secure spread spectrum watermarking for multimedia,” IEEE Trans. Image Processing, vol. 6, pp. 1673-1687, Dec. 1997
Example India Image in another image
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