Data Hiding in Image and Video: Part II—Designs and Applications Min Wu, Heather Yu, and Bede Liu.
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Transcript of Data Hiding in Image and Video: Part II—Designs and Applications Min Wu, Heather Yu, and Bede Liu.
Data Hiding in Image and Video:Part II—Designs and Applications
Min Wu, Heather Yu, and Bede Liu
Outlines
Introduction
Multilevel Data Hiding in Grayscale Image
Multilevel Data Hiding in Video
Conclusion
Introduction
Goal: apply the solutions in Part I to specific design
problems and present details of embedding data
Multilevel Data Hiding in Grayscale Image
Introduction
Spectrum Partition
System Design
Experimental Results
Multilevel Data Hiding in Grayscale Image -- Introduction
Present a two-level data hiding using two types of embedding mechanisms Basis: Fig5. in Part I
Basic Assumptions/Conditions: Grayscale Images Embedding Domain: 8*8 block DCT coefficients Using Spectrum Segments for Embedding Dealing with non-coherent case
Multilevel Data Hiding in Grayscale Image -- Introduction
Spectrum Partition
Data Model and Formula
Experimental Results
Spectrum Partition-Data Model(1)
Embedding:
where the watermark {s1, …, sn } is an n-sample known
sequence, b: a bit to be embedded and is equally likely to be “-1”
or “+1”, di: noise, i.i.d. Gaussian
Spectrum Partition-Data Model(2)
A few considerations Bits can be embedded in all bands. In many
cases, bits are embedded in mid-band due to Low band coefficients generally have higher power High band coefficients are vulnerable to attacks
Noise Model can be extended to Normal Distribution with Various Covariance. Whitening should be performed in such cases
Spectrum Partition-Data Model(3)
The detector
The mean
Spectrum Partition-Simulation(1)
Subject: 141 ImagesEmbedding: the Block-DCT spread spectrum algorithm proposed by Podilchuk-ZengDetection: the q-statistic proposed by Zeng-LiuThree watermarks are usedPre-processing: An estimation of the host signal’s power is performed
based on testing images A set of known signals are added to help locating host
signal from noise
Spectrum Partition-Simulation(2)
Detection: Defined two statistics: q’ and q, with and without the weighting
Spectrum Partition-Simulation(3)
Experiments: DCT coefficients are ordered in zig-zag order Several distortion are introduced while computing q-statistics
JPEG with different quality factors Low pass filtering
q-statistics are normalized with respect to number of embeddable coefficients, see Figures
Q is maximum when the embedding starts around 6-11 Q’ is larger than q and it’s monotone
Conclusion: For high robustness, embed the bit to mid-band coefficients For high payload, embed the bit to low-band coefficients
Spectrum Partition-Simulation(4)
Spectrum Partition-Simulation(5)
Spectrum Partition-Simulation(6)
System Design
Block Diagram
Two Level Embedding
System Design– Block Diagram(1)
Embedding
System Design– Block Diagram(2)
Detecting
Two Level Embedding(1)
First Level: Using Odd-Even Embedding in the Low Band Quantization Techniques are applied
Two Level Embedding(2)
Second Level: Using Type I Spread Spectrum Technique Antipodal Modulation Is Used
where {vi}: original coefficients{vi’}: marked coefficients{b’}: antipodal mapping from b, which is +1 or –1 : watermark strength, adjusted by the just-noticeable-
difference (JND) standard
Experimental Results
Multilevel Data Hiding in Video
Embedding Domain
Variable Embedding Rate (VER) Versus Constant Embedding Rate (CER)
Control Data Versus User Data
Experimental Results
Embedding Domain(1)
Problems Introduced by Consecutive Frames Add/Drop Some Frames Switch the Order of Frames Generate New Frames
Possible Attacks Collusion Attack
Solution Adding Redundancy
Embedding Domain(2)
To Avoid Frame-Jitter Partitioning the Video into Temporal Segments Embedding Same Data in Every Frame of a
Segment
Embedding Domain(3)
To Avoid Frame Drop, Reordering, Insertion Embedding the Same User Data As Well As a
Shorten Version of Segment Index The Segment Index Is Part Of the Control Bits
Variable Embedding Rate (VER) vs. Constant Embedding Rate (CER)
Problem The Uneven Embedding Capacity Arises Both From
Region to Region within a Frame and From Frame to Frame
Solution Combine VER and CER
The Intra-Frame Unevenness Is Handled by CER and Shuffling
The Inter-Frame Unevenness Is Handled by VER and Additional Side Information
Number of Bits Embedded in Each Frame
Number of Bits That Can Be Embedded in Each Frame Changes Greatly Estimate Number of Bits for Each Frame Estimate the Achievable Embedding Payload
Based on Energy of DCT Coefficients, Number of Embeddable Coefficients
Set Two Threshold and If do not embed data If a number of bits are embedded
If bits are embedded in higher rate
1 2
C
1C 1 2C
2C
Estimation of Payload
For Type I Spread Spectrum Embedding, The Mean of Detection Statistic Is Bit Error Probability Is Given by Maximum Bit Error Probability Is Given by A Lower Bound of Mean Detection Statistic Is Defined by
The Detection Statistic When All Embeddable Coefficients Are Used Is Given By
The Payload Is
( )E T( ( ))Q E T
(max)eP
0T
1 (max)( )th eT Q P
Control Data Versus User Data(1)
Control Data: Additional Information Include Frame Sync Index, Number of Bits
Embedded in Each Frame
Embedding Frame Sync A Short Version of Video Segment Index Assume Frame Sync’s Range is 0 to K-1 The i-th Segment Is Labeled as mod( , )i K
Control Data Versus User Data(2)
User Data: Information
TDM with Shuffling IS Applied
Orthogonal Modulation Is Used to Double the Number of Embedded Bits Assume 2B bits Are Embedded
Block Diagram
Experimental Results
Conclusion
Demonstrate How to Apply General Solutions in Part I to Specific Designs
Made use of Two types of Embedding Modulation and Multiplex Techniques Shuffling Multilevel Data Hiding