1. Digital Watermarking: Principles and Practices
Dr. Latha Parameswaran
AMRITA University
India
Digital Watermarking

2. Achieved using INFORMATION HIDING
Significance
Vast multimedia content in Internet
Availability of economical and simple tools - easy to pirate and alter contents
Secure Intellectual Property Rights (IPR)
Digital Rights Management (DRM
Achieved using INFORMATION HIDING
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Digital Watermarking: Latha Parameswaran

3. Digital Watermarking: Latha Parameswaran
Motivation
Motivation
The distribution of digital media is becoming faster, easier and requiring less effort to make exact copies
How to protect the intellectual property?
Conventional approaches
In analog world: signature, steel seal, embossed portrait, copyright label...
In digital world: Cryptology, Watermarking
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Digital Watermarking: Latha Parameswaran

4. Significance: Sample Scenario
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5. Digital Watermarking: Latha Parameswaran
Information Hiding
Information Hiding is a general term encompassing many sub disciplines
Two important sub disciplines are:
Steganography and watermarking
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Digital Watermarking: Latha Parameswaran

6. Digital Watermarking: Latha Parameswaran
Solutions Available
Steganography - the art of concealed communication
Watermarking - the practice of hiding a message in a media
Cryptography - the practice of keeping messages secret
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Digital Watermarking: Latha Parameswaran

7. Digital Watermarking: Latha Parameswaran
What is a Watermark ?
A distinguishing mark or device impressed in the substance of a sheet of paper during manufacture, usually barely noticeable except when the sheet is held against strong light
to make forgery more difficult
to record the manufacturer’s trademark
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Digital Watermarking: Latha Parameswaran

8. Watermarking - Framework
Digital Watermark:
- piece of information hidden in a multimedia content - imperceptible to a human observer, but, easily detected by a computer
Watermarking:
- process of hiding the watermark imperceptibly in the content.
Encryption:
- protects content during the transmission of the data from the sender to receiver - after decryption, the data is not protected
WATERMARKING COMPLEMENTS ENCRYPTION
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Digital Watermarking: Latha Parameswaran

9. Digital Watermarking: Latha Parameswaran
A digital watermark
a digital signal or pattern imposed on a digital document ( text, graphics, multimedia presentations )
visible watermark
the more obvious means of discouraging unauthorized use by reducing the commercial value of a document
invisible watermark
the watermark is imperceptible to the human eye
when the ownership of data is in question, the watermark will then be extracted to characterize the ownership
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Digital Watermarking: Latha Parameswaran

10. Digital Watermarking: Latha Parameswaran
Watermarking History
More than 700 years ago - Italy - indicate the paper brand and the mill that produced it
18th century - used as anti counterfeiting measures on money and other documents
Term “Watermark” - introduced - end of the 18th century.
First example – similar technology - patent filed in 1954 by Emil Hembrooke - identifying music works
In 1988, Komatsu and Tominaga appear to be the first to use the term “Digital Watermarking”
Since 1995, WATERMARKING ERA ….
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Digital Watermarking: Latha Parameswaran

11. Watermarking Definition
A practice of imperceptibly altering a cover to embed a message about that cover
Often used whenever the cover is available to parties who know the existence of the hidden data and may have an interest in removing it – additional notion of resilience against attempts to remove the hidden data
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12. Basic Design of a Watermarking System
Original
work
Watermark
embedder
Watermark
detector
Watermarked
work
(looks like
original)
Detected
message
Message
(regarding
work)
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13. Watermarking Applications
1. Copyright protection
Most prominent application
Embed information about the owner to prevent others from claiming copyright
Require very high level of robustness
2. Copy protection
Embed watermark to disallow unauthorized copying of the cover
For example, a compliant DVD player will not playback or copy data that carry a “copy never” watermark
3. Content Authentication
Embed a watermark to detect modifications to the cover
The watermark in this case has low robustness, “fragile”
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14. Watermarking Applications …
4. Transaction Tracking
Embed a watermark to convey information about the legal recipient of the cover
This is useful to monitor or trace back illegally produced copies of the cover
This is usually referred to as “fingerprinting”
5. Broadcast Monitoring
Embed a watermark in the cover and use automatic monitoring to verify whether cover was broadcasted as agreed
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Digital Watermarking: Latha Parameswaran

15. Watermarking Characteristics
Imperceptibility
The modifications caused by watermark embedding should be below the perceptible threshold
Robustness
The ability of the watermark to resist distortion introduced by standard or malicious data processing
Security
A watermark is secure if knowing the algorithms for embedding and extracting does not help unauthorized party to detect or remove the watermark
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16. Watermarking Characteristics
Payload
The amount of information that can be stored in a watermark
Informed (non oblivious, or private)
The original un watermarked cover is required to perform the extraction process
Blind (oblivious, or public)
The original un watermarked cover is NOT required to perform the extraction process
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17. Challenges in Watermarking
Making the watermark robust is not trivial
with complete knowledge
any watermark can theoretically be removed
with partial knowledge
the removal may interfere with the viewing of the data
the effort of removal is greater than the value of the data
Challenges from data compression
Whatever hole one may find to fill with
watermark is likely to be eliminated by data compression
Robustness
Imperceptibility
Capacity
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18. Digital Watermarking: Latha Parameswaran
Attacks
Signal enhancement (sharpening, contrast enhancement, etc.)
Additive and multiplicative noise (gaussian, uniform, etc.)
Filtering (High pass, low pass, linear, nonlinear, etc.)
Lossy compression (JPEG, MPEG-x, etc.)
Geometric transforms (RST)
Data reduction (cropping, clipping, etc.)
D/A and A/D conversion (print-scan, etc.)
Multiple watermarking, Collusion attack, Mosaic attack
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19. Watermarked Image Corrupted Watermarked Image
Transmission
Lossy Compression
Geometric Distortions
Signal Processing
D/A - A/D Conversion
Typical Distortions or Intentional Tampering
Transmission
Corrupted Watermarked Image
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Digital Watermarking: Latha Parameswaran

20. Digital Watermarking: Latha Parameswaran
Types of Watermarks
Perceptibility: Visible / Invisible
Robustness: Fragile/ Semi Fragile/ Robust
Extraction Method: Blind / Informed
Inserted Media: Text / Audio/ Video
Watermark: Noise / Image
Processing Domain: Spatial / Frequency
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21. Random sequence watermark Visually recognizable watermark
Digital watermark
Visible watermark
Invisible watermark
Random sequence watermark
Visually recognizable watermark
Watermark :
Verification :
ID number (random number)
Visually recognizable pattern
Quantitative measurement of the detection
Extracted pattern & Quantitative measurement
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Digital Watermarking: Latha Parameswaran

22. Digital Watermarking: Latha Parameswaran
Watermarking Types
Private or non-blind
requires host image or watermark during watermark extraction
Semi-private or semi-blind
does not require the host image but requires watermark for extraction
Public or blind
does not require host or watermark for extraction
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23. Another classification
Robust watermarking
resist legitimate, content-preserving, unintentional modifications
Applications: copyright protection and content tracking
Fragile watermarking
are sensitive, to the slightest modification of the watermarked image
Applications: Content Authentication in sensitive documents like medical images
Semi-fragile watermarking
tolerates some degree of legitimate modifications
identify regions of suspected alterations
Applications: Content Authentication
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Digital Watermarking: Latha Parameswaran

24. Performance Evaluation Metrics (after embedding)
Difference distortion metrics
Mean Square Error (MSE)
Peak Signal to Noise Ratio (PSNR)
Image Fidelity (IF)
Correlation-based metrics
Normalized Cross Correlation (NCC)
Pearson Correlation Coefficient (PCC)
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25. Performance Evaluation Metrics (after extraction)
Linear
Correlation
Normalized Correlation
Coefficient
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26. Digital Watermarking: Latha Parameswaran
Watermarking Phases
Watermark Embedding
Embed watermark in watermark carriers (DCT, DWT, …) of the host data
May be corrupted by noise, compressed, etc. during transmission
Watermark Extraction
Extract the embedded watermark from the carriers
Extracted watermark may vary from embedded
Compute the watermark from the received data
Measure closeness by metrics like correlation
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27. Watermarking - overview
Watermarked image
Modified watermarked image
Extracted watermark W*
Host image I
Watermark
embedding
Unintentional and intentional modifications
Watermark extraction I’
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Digital Watermarking: Latha Parameswaran

28. Watermark Generation and Embedding
Modified watermarked image I’
Watermarked image W
Watermark
Host image
Compute
features
Embed
the watermark
(watermark carriers – DCT, DWT…)
Select features and generate watermark
(spatial domain or transform domain) I
Unintentional and intentional modifications
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Digital Watermarking: Latha Parameswaran

29. Watermark Extraction and AuthenticationNo
Yes W’
Modified watermarked image
Compute
features
Extract
the embedded
watermark
Select features and generate watermark I’
W’ ≈W*?
Image is authentic
Image is unauthentic
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30. Digital Watermarking: Latha Parameswaran
Watermark Generation
Compute salient features of the image
in spatial domain like edges, texture, fractal dimensions
in transform domain such as singular values, eigenvalues
random binary sequence
digital signature
other features
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Digital Watermarking: Latha Parameswaran

31. Digital Watermarking: Latha Parameswaran
Watermark Carriers
Embed watermark in watermark carriers:
Discrete Fourier Transform (DFT)
Discrete Walsh-Hadamard Transform (DWHT),
Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT)
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32. Digital Watermarking: Latha Parameswaran
Watermark Embedding
Quantization approach
quantize the original data using a quantization function
determine embedding strength using minimal distance method
Related work
[2], [10], [55], and [62]–[64]
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33. Digital Watermarking: Latha Parameswaran
Watermark Embedding
Modulation approach
I denotes the host image
I* denotes the watermarked image
W denotes the watermark
α denotes embedding strength
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Digital Watermarking: Latha Parameswaran

34. Watermark Extraction and Verification
Three step process:
Extract the embedded watermark from the received image
Compute watermark from the received image using the same watermark generation procedure
Compare extracted watermark with the computed watermark using the correlation metric - Verification
Non- blind, Semi-blind, Blind
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35. Digital Watermarking: Latha Parameswaran
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36. Digital Watermarking: Latha Parameswaran
Sample Scenarios
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37. Digital Watermarking: Latha Parameswaran
Sample Scenarios
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38. Digital Watermarking: Latha Parameswaran
Sample Scenario
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Digital Watermarking: Latha Parameswaran

39. Digital Watermarking: Latha Parameswaran
Sample Scenario
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Digital Watermarking: Latha Parameswaran

40. Digital Watermarking: Latha Parameswaran
Sample Scenario
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41. Digital Watermarking: Latha Parameswaran
Sample Scenario
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Digital Watermarking: Latha Parameswaran

42. Digital Watermarking: Latha Parameswaran
What next ?
Is the interest warranted?
What are the existing and potential commercial applications of this technology?
What scientific progress has been made in the past 10 years?
What are the most exciting areas for research?
Where might the next 10 years take us?
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43. Digital Watermarking: Latha Parameswaran
Current Standards
The CPTWG (Copy Protection Technical Working Group) tested watermarking systems for protection of video on DVD disks.
The SDMI (Secure Digital Music Initiative) made watermarking a core component in their system for music protection.
Two projects sponsored by the European Union, VIVA and Talisman, tested watermarking for broadcast monitoring.
The ISO (International Organization for Standardization) took an interest in the context of designing advanced MPEG standards. (MPEG-21)
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44. Digital Watermarking: Latha Parameswaran
Problems Faced
Initial expectations of watermarking are too high
Security against intentional efforts to remove a watermark from content
Request for proposal met specifications
Slow adoption of watermarking techniques
Mainly due to the diverge business interests of the three industry groups
Content owner
Manufacturers of consumer electronics
Manufactures of computers
Is the current business and academic interest in watermarking warranted?
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Digital Watermarking: Latha Parameswaran

45. Digital Watermarking: Latha Parameswaran
Business Perpective
Can watermarking provide economic solutions to real problems?
Current business interests
Security
Current watermark solutions are of weak sucurity, but suitable for many business models
Device control
No security threat or requirements
Linking traditional media to the Web is receiving increased attention.
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46. Digital Watermarking: Latha Parameswaran
What is in research?
Some advances are in their infancy, and much work remains to be done.
Some results are imminent, making an area exciting. While in other cases, no breakthroughs are found on the horizon.
Possible research topics
Informed embedding
Geometric/temporal distortions in a blind detector
Optimally embedding with fidelity and robustness constraints
Whether a watermarking system can be designed that permits public detection while preventing an adversary form removing the watermark. (The authors are divided in this problem)
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47. Digital Watermarking: Latha Parameswaran
Conclusion
No standards have been derived
An exhaustive list of open problems
A significant area of research
Wide applications
Industry – Academia relation builder
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48. Digital Watermarking: Latha Parameswaran
Questions?
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Digital Watermarking: Latha Parameswaran