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Digital Watermarking
Digital Watermarking: Principles and
Practices
Dr. Latha ParameswaranAMRITA University
India
April 21, 2023
Digital Watermarking: Latha Parameswaran
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 HIDINGAchieved using INFORMATION HIDING
April 21, 2023
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 propertyHow to protect the intellectual property?
Conventional approaches
In analog world: signature, steel seal,
embossed portrait, copyright label...
In digital world: Cryptology, Watermarking
April 21, 2023
Digital Watermarking: Latha Parameswaran
Significance: Sample Scenario
April 21, 2023
Digital Watermarking: Latha Parameswaran
Information Hiding
Information Hiding is a general term
encompassing many sub disciplines
Two important sub disciplines are:
Steganography and watermarking
April 21, 2023
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
April 21, 2023
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
April 21, 2023
Digital Watermarking: Latha Parameswaran
Watermarking - Framework
Digital WatermarkDigital Watermark:
- piece of information hidden in a multimedia content - imperceptible to a human observer, but, easily detected by a computer
Watermarking:Watermarking:
- process of hiding the watermark imperceptibly in the content.
Encryption:Encryption:
- protects content during the transmission of the data from the sender to receiver - after decryption, the data is not protected
WATERMARKING COMPLEMENTS ENCRYPTIONWATERMARKING COMPLEMENTS ENCRYPTION
April 21, 2023
Digital Watermarking: Latha Parameswaran
Digital Watermark ?
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
April 21, 2023
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 ERAWATERMARKING ERA ….
April 21, 2023
Digital Watermarking: Latha Parameswaran
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
April 21, 2023
Digital Watermarking: Latha Parameswaran
Basic Design of a Watermarking System
Originalwork
Message(regarding
work)
Watermarkembedder
Watermarkedwork
(looks likeoriginal)
Watermarkdetector
Detectedmessage
April 21, 2023
Digital Watermarking: Latha Parameswaran
Watermarking Applications
1. 1. Copyright protectionCopyright protection Most prominent application Embed information about the owner to prevent
others from claiming copyright Require very high level of robustness
2. 2. Copy protectionCopy 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. 3. Content Authentication Embed a watermark to detect modifications to
the cover The watermark in this case has low robustness,
“fragile”
April 21, 2023
Digital Watermarking: Latha Parameswaran
Watermarking Applications …
4. 4. Transaction TrackingTransaction 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. 5. Broadcast MonitoringBroadcast Monitoring
Embed a watermark in the cover and use
automatic monitoring to verify whether cover
was broadcasted as agreed
April 21, 2023
Digital Watermarking: Latha Parameswaran
Watermarking Characteristics
ImperceptibilityImperceptibilityThe modifications caused by watermark
embedding should be below the perceptible threshold
RobustnessRobustnessThe ability of the watermark to resist
distortion introduced by standard or malicious data processing
SecuritySecurityA watermark is secure if knowing the
algorithms for embedding and extracting does not help unauthorized party to detect or remove the watermark
April 21, 2023
Digital Watermarking: Latha Parameswaran
Watermarking Characteristics
PayloadPayload The amount of information that can be
stored in a watermark
Informed (non oblivious, or private)Informed (non oblivious, or private) The original un watermarked cover is
required to perform the extraction process
Blind (oblivious, or public)Blind (oblivious, or public) The original un watermarked cover is
NOT required to perform the extraction process
April 21, 2023
Digital Watermarking: Latha Parameswaran
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
Capacity
Robustness
Imperceptibility
April 21, 2023
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
April 21, 2023
Digital Watermarking: Latha Parameswaran
Watermarked Image
Transmission
Corrupted Watermarked Image
Transmission
Lossy Compression
Geometric Distortions
Signal Processing
D/A - A/D Conversion
Typical Distortions or Intentional Tampering
April 21, 2023
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
April 21, 2023
Digital Watermarking: Latha Parameswaran
Visible watermark Invisible watermark
Random sequence watermark
Visually recognizable watermark
Digital watermark
Watermark :
Verification :
ID number (random ID number (random number)number)
Quantitative measurement Quantitative measurement of the detectionof the detection
Visually recognizable Visually recognizable patternpattern
Extracted pattern & Extracted pattern & Quantitative measurementQuantitative measurement
April 21, 2023
Digital Watermarking: Latha Parameswaran
Watermarking Types
Private or non-blindPrivate or non-blind
requires host image or watermark during
watermark extraction
Semi-private or semi-blindSemi-private or semi-blind
does not require the host image but requires
watermark for extraction
Public or blindPublic or blind
does not require host or watermark for extraction
April 21, 2023
Digital Watermarking: Latha Parameswaran
Another classification
Robust watermarkingRobust watermarking
resist legitimate, content-preserving, unintentional
modifications
Applications: copyright protection and content tracking
Fragile watermarkingFragile watermarking
are sensitive, to the slightest modification of the watermarked
image
Applications: Content Authentication in sensitive documents like
medical images
Semi-fragile watermarkingSemi-fragile watermarking
tolerates some degree of legitimate modifications
identify regions of suspected alterations
Applications: Content Authentication
April 21, 2023
Digital Watermarking: Latha Parameswaran
Performance Evaluation Metrics(after embedding)
Difference distortion metricsDifference distortion metrics
Mean Square Error (MSE)Mean Square Error (MSE)
Peak Signal to Noise Ratio (PSNR)Peak Signal to Noise Ratio (PSNR)
Image Fidelity (IF)Image Fidelity (IF)
Correlation-based metricsCorrelation-based metrics
Normalized Cross Correlation (NCC)Normalized Cross Correlation (NCC)
Pearson Correlation Coefficient (PCC)Pearson Correlation Coefficient (PCC)
2*2
1
IIn
MSE
I 210
maxlog10
22
*
1
I
II
2
*
I
II
)()( *22
**
II
IIII
April 21, 2023
Digital Watermarking: Latha Parameswaran
Performance Evaluation Metrics(after extraction)
Linear Correlation
Normalized Correlation
CorrelationCoefficient
i
iwiwN
wwLC )()(1
),( '*'*
i
iwiwNC )(~)(~ '*
*
**~
w
ww
)~,~( '* wwNCCC
)(~ *** www
'
''~w
ww
'''~ www
April 21, 2023
Digital Watermarking: Latha Parameswaran
Watermarking Phases
1. Watermark Embedding
Embed watermark in watermark carriers (DCT,
DWT, …) of the host data May be corrupted by noise, compressed, etc.
during transmission
2. 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
April 21, 2023
Digital Watermarking: Latha Parameswaran
Watermarking - overview
I*
Watermarked image
Modified watermarked
image
Extracted watermark
W*
Host image
IWatermarkembedding
Unintentional and intentional
modifications
Watermark extraction
I’
April 21, 2023
Digital Watermarking: Latha Parameswaran
Watermark Generation and Embedding
I*I*
Modified Modified watermarked watermarked
imageimage
I’I’
Watermarked Watermarked imageimage
WW Watermark Watermark
Host imageHost image
ComputeComputefeaturesfeatures
EmbedEmbedthe watermarkthe watermark
(watermark (watermark carriers – DCT, carriers – DCT,
DWT…)DWT…)
Select features and Select features and generate watermarkgenerate watermark(spatial domain or (spatial domain or transform domain)transform domain)
II
Unintentional and Unintentional and intentional intentional
modificationsmodifications
April 21, 2023
Digital Watermarking: Latha Parameswaran
Watermark Extraction and Authentication
W*W*
NoNo
YesYes
W’W’
Modified Modified watermarked watermarked imageimage
ComputeComputefeaturesfeatures
ExtractExtractthe embeddedthe embedded
watermarkwatermark
Select features and Select features and generate watermarkgenerate watermark
I’I’
W’ W’ ≈W*?≈W*?
Image is Image is authenticauthentic
Image is Image is unauthenticunauthentic
April 21, 2023
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
April 21, 2023
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)
April 21, 2023
Digital Watermarking: Latha Parameswaran
Watermark Embedding
1. 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]
April 21, 2023
Digital Watermarking: Latha Parameswaran
Watermark Embedding
2. Modulation approach
I denotes the host image I* denotes the watermarked image W denotes the watermark α denotes embedding strength
April 21, 2023
Digital Watermarking: Latha Parameswaran
Watermark Extraction and Verification
Three step process:
1. Extract the embedded watermark from the received image
2. Compute watermark from the received image using the same watermark generation procedure
3. Compare extracted watermark with the computed watermark using the correlation metric - Verification
Non- blind, Semi-blind, Blind
April 21, 2023
Digital Watermarking: Latha Parameswaran
April 21, 2023
Digital Watermarking: Latha Parameswaran
Sample Scenarios
April 21, 2023
Digital Watermarking: Latha Parameswaran
Sample Scenarios
April 21, 2023
Digital Watermarking: Latha Parameswaran
Sample Scenario
April 21, 2023
Digital Watermarking: Latha Parameswaran
Sample Scenario
April 21, 2023
Digital Watermarking: Latha Parameswaran
Sample Scenario
April 21, 2023
Digital Watermarking: Latha Parameswaran
Sample Scenario
April 21, 2023
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?
April 21, 2023
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)
April 21, 2023
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?
April 21, 2023
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.
April 21, 2023
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)
April 21, 2023
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
April 21, 2023
Digital Watermarking: Latha Parameswaran
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