Introduction to Watermark.ppt

Introduction to WatermarkIntroduction to Watermark

AdvisorAdvisor ：杭學鳴教授：杭學鳴教授StudentStudent ：朱育成：朱育成

OutlineOutline

Review of watermarkingReview of watermarking Applications and examples of watermarkingApplications and examples of watermarking Some architectures of watermarking combined Some architectures of watermarking combined

with other techniqueswith other techniques

Motive of watermarkingMotive of watermarking

Recent advancements in computer technologies Recent advancements in computer technologies offer many facilities for duplication, distribution, offer many facilities for duplication, distribution, creation, and manipulation of digital contents.creation, and manipulation of digital contents.

Encryption is useful for transmission but does Encryption is useful for transmission but does not provide a way to examine the original data in not provide a way to examine the original data in its protected form.its protected form.

Watermarking processWatermarking process

1)1) Embedding stageEmbedding stage– Spatial domainSpatial domain

flipping the low-order bit of each pixelsflipping the low-order bit of each pixels

– Frequency domainFrequency domain embedding the watermark in mid-frequency componentsembedding the watermark in mid-frequency components relatively robust to noise, image processing and compressionrelatively robust to noise, image processing and compression the quality of the host image will be distorted significantly if too the quality of the host image will be distorted significantly if too

much data is embedded much data is embedded

2)2) Distribution stageDistribution stage– Compression, transmission error, and common image Compression, transmission error, and common image

processing are seen as an attack on the embedded processing are seen as an attack on the embedded informationinformation

Watermarking processWatermarking process

3)3) Extraction stageExtraction stage– Blind – extraction without original imageBlind – extraction without original image

– Semi-blind – rely on some data or featuresSemi-blind – rely on some data or features

– Non-blind – need original imageNon-blind – need original image

4)4) Detection stageDetection stage– Evaluate the similarity between the original and detected wEvaluate the similarity between the original and detected w

atermarkatermark False positiveFalse positive ：： watermark is detected although there is nonewatermark is detected although there is none False negativeFalse negative ：： no watermark is detected while there is oneno watermark is detected while there is one

Watermarking propertiesWatermarking properties

Perceptual transparencyPerceptual transparency RobustnessRobustness

– The mark should resist to The mark should resist to Common signal processing like lossy compressionCommon signal processing like lossy compression Geometric transformation like image rotation, scaling, and croppingGeometric transformation like image rotation, scaling, and cropping

SecuritySecurity– How easy it is to intentionally remove a watermarkHow easy it is to intentionally remove a watermark

Data capacityData capacity– Amount of information that can be stored within the contentAmount of information that can be stored within the content

Categories of digital watermarkCategories of digital watermark

PerceptiblePerceptible ImperceptibleImperceptible Robust Robust

– ownership assertionownership assertion FragileFragile

– indicate modifications of the contentindicate modifications of the content Semi-fragileSemi-fragile

– differentiate between lossy transformation that are “info. presdifferentiate between lossy transformation that are “info. preserving” and lossy transformation which are “info. altering”erving” and lossy transformation which are “info. altering”

ApplicationsApplications

Copyright ProtectionCopyright Protection– Invisible watermark which can tolerate malicious and Invisible watermark which can tolerate malicious and

unintentional attacksunintentional attacks

– It does not prevent people from copying the digital dataIt does not prevent people from copying the digital data

Data HidingData Hiding– It tries to invisibly embed the maximum amount of data into a It tries to invisibly embed the maximum amount of data into a

host signal => this allows communication using enciphered host signal => this allows communication using enciphered messages without attracting the attention of a third partymessages without attracting the attention of a third party

– Robustness is not important while invisibility and capacity Robustness is not important while invisibility and capacity are requiredare required


Authentication and Data IntegrityAuthentication and Data Integrity– Verification watermarks are required to be fragile, so that any Verification watermarks are required to be fragile, so that any

modification to the image will destroy the markmodification to the image will destroy the mark

Copy ProtectionCopy Protection– RequirementsRequirements

Robustness against removalRobustness against removal Ability of blind detectionAbility of blind detection Capability of conveying non-trivial number of bitsCapability of conveying non-trivial number of bits


FingerprintingFingerprinting– Trace the source of illegal copiesTrace the source of illegal copies

Different watermarks are embedded by the owner in the copies of the Different watermarks are embedded by the owner in the copies of the data that are supplied to different customersdata that are supplied to different customers

Transparency and robustness are requiredTransparency and robustness are required

Examples of watermarkingExamples of watermarking

Image WatermarkingImage Watermarking Document WatermarkingDocument Watermarking Graphics watermarkingGraphics watermarking Video watermarkingVideo watermarking

Image WatermarkingImage Watermarking

Robust and imperceptible Robust and imperceptible – The watermark may be scaled appropriately to minimize noticThe watermark may be scaled appropriately to minimize notic

eable distortion to the hosteable distortion to the host

ExamplesExamples– Texture-based watermarkTexture-based watermark

Embed it into a portion of the image with similar textureEmbed it into a portion of the image with similar texture

– Insert a watermark into the phase componentsInsert a watermark into the phase components The phase information is perceptually more inportant than the magnituThe phase information is perceptually more inportant than the magnitu

de datade data

Document WatermarkingDocument Watermarking

Line-shiftsLine-shifts Word-shiftsWord-shifts

Document WatermarkingDocument Watermarking

Slight modifications to charactersSlight modifications to characters

Graphics WatermarkingGraphics Watermarking

Embedding in facial animation parameter (FAP) dataEmbedding in facial animation parameter (FAP) data– The amount of deviation the watermark signal has on FAP is The amount of deviation the watermark signal has on FAP is

limited to minimize visible distortionlimited to minimize visible distortion 1% for head rotation1% for head rotation 3% for lip motion3% for lip motion

Video WatermarkingVideo Watermarking

Copy generation managementCopy generation management– Minimum information that must conveyMinimum information that must convey

Copy neverCopy never Copy onceCopy once Copy no moreCopy no more Copy freelyCopy freely

For DVD, real-time decoding is requiredFor DVD, real-time decoding is required Detector placementDetector placement

– Detection in the driveDetection in the drive

– Detection within the application (within MPEG decoder)Detection within the application (within MPEG decoder)

Video WatermarkingVideo Watermarking

ExamplesExamples– For video coding like MPEG or H.26x, we embed the For video coding like MPEG or H.26x, we embed the

watermark into DCT coefficients watermark into DCT coefficients Only partial decoding of block DCT is necessary for watermark Only partial decoding of block DCT is necessary for watermark

embeddingembedding If constant bit rate is required, only nonzero DCT coefficients are If constant bit rate is required, only nonzero DCT coefficients are

markedmarked

Layered Access Control Schemes on Layered Access Control Schemes on Watermarked Scalable MediaWatermarked Scalable Media

Scalability – spatial, temporal and SNR scalabilityScalability – spatial, temporal and SNR scalability A typical MPEG-2 conditional access receiverA typical MPEG-2 conditional access receiver


A typical MPEG-2 conditional access receiverA typical MPEG-2 conditional access receiver– Control Word – change very often so that fast (simple) Control Word – change very often so that fast (simple)

decryption algorithm would not be broken easilydecryption algorithm would not be broken easily

– EMM (Entitlement Management Message) – with the aid of EMM (Entitlement Management Message) – with the aid of EMM, the broadcaster can change the status of the user EMM, the broadcaster can change the status of the user accessibility of contentsaccessibility of contents

– ECM (Entitlement Control Message)ECM (Entitlement Control Message)


A typical MPEG-2 conditional access receiverA typical MPEG-2 conditional access receiver– ProblemProblem

We send the key to user via reliable channel, while the content goes We send the key to user via reliable channel, while the content goes through an unreliable channel.through an unreliable channel.

Key and contents won’t arrive at the same timeKey and contents won’t arrive at the same time=> Synchronization problem=> Synchronization problem

– SolutionSolution Using robust watermark to embed the ECM and EMM information Using robust watermark to embed the ECM and EMM information

into the contentinto the content


Receiver architecture of the proposed methodReceiver architecture of the proposed method


Receiver architecture of the proposed methodReceiver architecture of the proposed method– Current layer is decrypt by the key Ki extracted from past layCurrent layer is decrypt by the key Ki extracted from past lay

erer– The user key Gi should be obtained before receiving media daThe user key Gi should be obtained before receiving media da

ta, for instance, by manually or automatically update after subta, for instance, by manually or automatically update after subscriptionscription

ConclusionConclusion– Cryptography does not provide error tolerance. By combining Cryptography does not provide error tolerance. By combining

cryptography and robust watermarking techniques, the key recryptography and robust watermarking techniques, the key receives stronger error-protection since the robust watermark caceives stronger error-protection since the robust watermark can tolerate transmission errors/attacksn tolerate transmission errors/attacks

– The key is implicitly synchronized to the contentThe key is implicitly synchronized to the content

A Novel Public Watermarking System A Novel Public Watermarking System based on Advanced Encryption Systembased on Advanced Encryption System

MotiveMotive– Almost proposed watermarking methods keep the Almost proposed watermarking methods keep the

watermarking algorithm private to ensure the embedded watermarking algorithm private to ensure the embedded watermark secretwatermark secret

Proposed watermark embedding algorithmProposed watermark embedding algorithm– 2 different watermarks for the spatial and frequency domain 2 different watermarks for the spatial and frequency domain

separatelyseparately Robust watermark for frequency domainRobust watermark for frequency domain Fragile watermark is embedded into the LSB plane in spatial domainFragile watermark is embedded into the LSB plane in spatial domain

A Novel Public Watermarking System bA Novel Public Watermarking System based on Advanced Encryption Systemased on Advanced Encryption System

Robust watermark embedding algorithmRobust watermark embedding algorithm1.1. WWRSRS = RS_Encode(Wo) = RS_Encode(Wo)

2.2. IIZZ = Set_LSB_Zero(Io) = Set_LSB_Zero(Io)

3.3. CSCS00 = DWT(I = DWT(IZZ))

4.4. MSCPS = Order_of_Significant_Coefficients(CSMSCPS = Order_of_Significant_Coefficients(CS00, k, ||W, k, ||WRSRS||)||)

C-MSCPS = Rijndael_Encrypt(MSCPS, K)C-MSCPS = Rijndael_Encrypt(MSCPS, K)WMPS = Select_Watermark_Positions(C-MSCPS, ||WWMPS = Select_Watermark_Positions(C-MSCPS, ||WRR

SS||)||)

5.5. CSCSww = Embed_Robust_Watermark(CS = Embed_Robust_Watermark(CS00, WMPS, W, WMPS, WRSRS))

6.6. IIwfwf = IDWT(CS = IDWT(CSww))


Robust watermark embedding algorithmRobust watermark embedding algorithm– Details in step 4Details in step 4

k||Wk||WRSRS|| most significant coefficients (MSC) of the LL ban|| most significant coefficients (MSC) of the LL band of CSd of CS00 are selected first are selected first

The order of these MSC is reordered in the descending ordThe order of these MSC is reordered in the descending order of magnitude to be MSCPSer of magnitude to be MSCPS

Cipher-MSCPS (C-MSCPS) is obtained by encrypting MSCipher-MSCPS (C-MSCPS) is obtained by encrypting MSCPS with a key K using the Rijndael block cipherCPS with a key K using the Rijndael block cipher

Finally, ||WFinally, ||WRSRS|| most significant bytes of C-MSCPS are sel|| most significant bytes of C-MSCPS are selected as the embedding positions => We embed the first biected as the embedding positions => We embed the first bit of Wt of WRSRS into the position corresponds to the most significa into the position corresponds to the most significant byte of the C-MSCPSnt byte of the C-MSCPS


Robust watermark embedding algorithmRobust watermark embedding algorithm– Examples of step 4Examples of step 4


Robust watermark embedding algorithmRobust watermark embedding algorithm– The watermarking method in step 5The watermarking method in step 5

If WIf WRSRS(i) = 0, then v(i) = 0, then vii’ = v’ = vi i (1 –α)(1 –α)

If WIf WRSRS(i) = 1, then v(i) = 1, then vii’ = v’ = vi i (1 +α)(1 +α)

– In sum, the watermark is added to the significant coeIn sum, the watermark is added to the significant coefficients of the LL band of the original image to ensufficients of the LL band of the original image to ensure its robustnessre its robustness


Fragile watermark embedding algorithmFragile watermark embedding algorithm7.7. IIwfzwfz = Set_LSB_Zero(I = Set_LSB_Zero(Iwfwf))

8.8. RS-ECC = Generate_RS_ECC(IRS-ECC = Generate_RS_ECC(Iwfzwfz)) RS-ECC contains all the parity check bits of Encoded Reed-SolomoRS-ECC contains all the parity check bits of Encoded Reed-Solomo

n coden code

9.9. C-RS-ECC = Rijndael_Encrypt(RS-ECC, K)C-RS-ECC = Rijndael_Encrypt(RS-ECC, K)

10.10. IIww = Embed_Fragile_Watermark(I = Embed_Fragile_Watermark(Iwfzwfz, C-RS-ECC), C-RS-ECC) All the LSB of IAll the LSB of Iwfwf are replaced with C-RS-ECC in a raster scan orde are replaced with C-RS-ECC in a raster scan orde

rr


ConclusionConclusion– The robust watermark WThe robust watermark WRSRS is used to carry the copyright infor is used to carry the copyright infor

mation while the fragile watermark C-RS-ECC is used to verimation while the fragile watermark C-RS-ECC is used to verify the image integrity and capable of providing the ability to rfy the image integrity and capable of providing the ability to recover altered imageecover altered image


Watermark Extraction ProcedureWatermark Extraction Procedure– Inspection phaseInspection phase

The test IThe test Iww’ image is inspected whether I’ image is inspected whether Iww’ is altered or not’ is altered or not

– Extraction phaseExtraction phase Inspection phaseInspection phase

1.1. (I(Iwzwz’, C-RS-ECC’) = Extract_Fragile_Watermark_and_Set_’, C-RS-ECC’) = Extract_Fragile_Watermark_and_Set_LSB_Zero(ILSB_Zero(Iww’)’)

2.2. RS-ECC’ = Rijndael_Decrypt(C-RS-ECC’, K)RS-ECC’ = Rijndael_Decrypt(C-RS-ECC’, K)RS-ECC = Generate_RS_ECC (IRS-ECC = Generate_RS_ECC (Iwzwz’)’)

3.3. If RS-ECC’ == RS-ECC, jump to Extraction phaseIf RS-ECC’ == RS-ECC, jump to Extraction phase

4.4. Fix_Image(IFix_Image(Iwzwz’, RS-ECC’)’, RS-ECC’)


Extraction phaseExtraction phase1.1. CSCSWW’ = DWT(I’ = DWT(Iwzwz’)’)

2.2. CSCS00 = DWT(I = DWT(IZZ))

3.3. MSCPS = Order_of_Significant_Coefficients(CSMSCPS = Order_of_Significant_Coefficients(CS00, k, ||W, k, ||WRSRS||)||)

C-MSCPS = Rijndael_Encrypt(MSCPS, K)C-MSCPS = Rijndael_Encrypt(MSCPS, K)WMPS = Select_Watermark_Positions(C-MSCPS, ||WWMPS = Select_Watermark_Positions(C-MSCPS, ||WRSRS||

|)|)

4.4. WWRSRS’ = Extract_Robust_Watermark(CS’ = Extract_Robust_Watermark(CSWW’, CS’, CS00, WMPS), WMPS) WWRSRS’(i) = 1, if v’(i) = 1, if vii’ > v’ > vii

WWRSRS’(i) = 0, if v’(i) = 0, if vii’ < v’ < vii

5.5. W’ = RS_Decode(WW’ = RS_Decode(WRSRS’)’)


Flow chart of watermark extractionFlow chart of watermark extraction

ReferenceReference

1.1. W.A. Wan Adnan, S. Hitam, S. Abdul-Karim, M.R.Tamjis, “A W.A. Wan Adnan, S. Hitam, S. Abdul-Karim, M.R.Tamjis, “A Review of Image Watermarking,” in Proceedings, Student ConReview of Image Watermarking,” in Proceedings, Student Conference on Research and Development, Aug. 2003, pp.381-384ference on Research and Development, Aug. 2003, pp.381-384

2.2. C.I. Podilchuk, E.J. Delp, “Digital WatermarkingC.I. Podilchuk, E.J. Delp, “Digital Watermarking ：： AlgorithmAlgorithms and Applications,” IEEE Signal Processing Magazine, Vol. 1s and Applications,” IEEE Signal Processing Magazine, Vol. 18 Issue 4, July 2001, pp. 33-468 Issue 4, July 2001, pp. 33-46

3.3. S.H. Kwok, C.C. Yang, K.Y. Tam, “Watermark Design Pattern S.H. Kwok, C.C. Yang, K.Y. Tam, “Watermark Design Pattern for Intellectual Property Protection in Electronic Commerce Afor Intellectual Property Protection in Electronic Commerce Applications,” in Proceedings of the 33rd Annual Hawaii Internapplications,” in Proceedings of the 33rd Annual Hawaii International Conference on System Sciences, Vol. 2, Jan 4-7 2000. tional Conference on System Sciences, Vol. 2, Jan 4-7 2000.

ReferenceReference

4.4. F.C. Chang, H.C. Huang, H.M. Hang, “Layered access control F.C. Chang, H.C. Huang, H.M. Hang, “Layered access control schemes on watermarked scalable media,” IEEE International schemes on watermarked scalable media,” IEEE International Symposium on Circuits and Systems, Vol. 5, May 2005, pp. 49Symposium on Circuits and Systems, Vol. 5, May 2005, pp. 4983-498683-4986

5.5. K.M. Chan, L.W. Chang, “A novel public watermarking systeK.M. Chan, L.W. Chang, “A novel public watermarking system based on advanced encryption system,” International Conferm based on advanced encryption system,” International Conference on Advanced Information Networking and Applications, ence on Advanced Information Networking and Applications, Vol. 1, 2004, pp. 48-52Vol. 1, 2004, pp. 48-52

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Introduction to Watermark.ppt