digital watermarking
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Digital Digital WatermarkingWatermarking
a Multimedia Security. . .a Multimedia Security. . .
PRESENTED BY-RAJIV RANJAN KR.
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Digital Watermarking?Digital Watermarking?
Allows users to embed Allows users to embed SPECIAL PATTERN SPECIAL PATTERN or or SOME SOME
DATA DATA into digital contents without changing its into digital contents without changing its perceptual quality.perceptual quality.
When data is embedded, it is not written at When data is embedded, it is not written at HEADER HEADER
PART PART but embedded directly into digital media itself but embedded directly into digital media itself by changing media contents databy changing media contents data
Watermarking is a key process for the Watermarking is a key process for the PROTECTIONPROTECTION of copyright of copyright ownership of electronic data.ownership of electronic data.
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Features of Features of WatermarkingWatermarking
Invisible/InaudibleInvisible/Inaudible Information is embedded without digital content Information is embedded without digital content
degradation, because of the level of embedding degradation, because of the level of embedding operation is too small for human to notice the change. operation is too small for human to notice the change.
InseparableInseparable The embedded information can survive after some The embedded information can survive after some
processing, compression and format transformation.processing, compression and format transformation. Unchanging data file sizeUnchanging data file size
Data size of the media is not changed before and after Data size of the media is not changed before and after embedding operation because information is embedded embedding operation because information is embedded directly into the media.directly into the media.
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How It WorksHow It Works
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CLASSIFICATION OF CLASSIFICATION OF WATERMARKWATERMARK
According to According to Human PerceptionHuman Perception (a)invisible(b)visible(a)invisible(b)visible
According to According to RobustnessRobustness (a)fragile(b)semi fragile(c)robust(a)fragile(b)semi fragile(c)robust
According to types of According to types of DocumentDocument (a)text(b)image(c)audio(d)video(a)text(b)image(c)audio(d)video
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CLASSIFICATION BYCLASSIFICATION BY“HUMAN “HUMAN
PERCEPTION”PERCEPTION”
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Visible WatermarkVisible Watermark Logo or seal of the organization which holds the Logo or seal of the organization which holds the
rights to the primary image, it allows the primary rights to the primary image, it allows the primary image to be viewed, but still visible it clearly as the image to be viewed, but still visible it clearly as the property of the owning organization.property of the owning organization.
Overlay the watermark in such a way that makes it Overlay the watermark in such a way that makes it difficult to remove, if the goal of indicating property difficult to remove, if the goal of indicating property rights is to be achieved. rights is to be achieved.
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Visible WatermarkVisible Watermark
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Invisible WatermarkInvisible Watermark
Embedding level is too small to noticeEmbedding level is too small to notice Can be retrieved by extraction softwareCan be retrieved by extraction software Applications:Applications:
AuthenticationAuthentication CopyrightingCopyrighting Etc…Etc…
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Invisible WatermarkInvisible Watermark
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CLASSIFICATION BY CLASSIFICATION BY “ROBUSTNESS”“ROBUSTNESS”
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Fragile/SemiFragile/RobustFragile/SemiFragile/Robust
A watermark is called A watermark is called fragilefragile if it fails to be if it fails to be detected after the slightest modification.detected after the slightest modification.
A watermark is called A watermark is called semi-fragilesemi-fragile if it resists if it resists begining transformations but fails detection begining transformations but fails detection after malignant transformations.after malignant transformations.
A watermark is called A watermark is called robustrobust if it resists a if it resists a designated class of transformations.designated class of transformations.
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CLASSIFICATION BY CLASSIFICATION BY “DOCUMENT”“DOCUMENT”
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Text/Image/Audio watermarkingText/Image/Audio watermarking
Text/Image/Audio watermarking refers to Text/Image/Audio watermarking refers to embedding watermarks in an text/image/audio embedding watermarks in an text/image/audio in order to protect the image from illegal in order to protect the image from illegal copying and identify manipulation.copying and identify manipulation.
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Video WatermarkingVideo Watermarking
Algorithm for video watermarking DFT DCT DWT
Watermarking in I-frame.
Video watermarking refers to embedding watermarks in Video watermarking refers to embedding watermarks in a video sequence in order to protect the video from a video sequence in order to protect the video from illegal copying and identify manipulationillegal copying and identify manipulation
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Discrete Cosine Discrete Cosine TransformationTransformation
DCT convert images from DCT convert images from spatial-domainspatial-domain to to frequency-frequency-domaindomain to decorrelate pixels to decorrelate pixels
The discrete cosine transform (DCT) helps to separate the The discrete cosine transform (DCT) helps to separate the image into parts of differing importance (with respect to the image into parts of differing importance (with respect to the image's visual quality). The DCT is similar to the discrete image's visual quality). The DCT is similar to the discrete Fourier transformFourier transform
Remember that JPEG breaks an image into 8x8 unitsSo for DCT n = 8
For example256 gray-scale image each pixel is stored as a value between 0 – 2550 = black pixel255 = white pixelValue between are shades of gray
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Wave TransformsWave Transforms
Frequency
Am
plit
ude
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DCT: One Dimensional DCT: One Dimensional
where
1
0
)(2
)12(cos
2)( )(
n
i
ifn
uip
nuF i
n = total no. of data item
p = pixel
F = coefficients
f(i)= is the intensity of the i th pixel
The general equation for a 1D (n data items) DCT is defined by the following equation:
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DCT: 2DDCT: 2D
),(2
)12(cos
2
)12(cos
22),(
1
0
1
0
)()(
jifm
vj
n
uipp
mnvuF
n
i
m
j
ji
•The input image is of size n by m;
•f(i,j) is the intensity of the pixel in row i and column j;
•F(u,v) is the DCT coefficient in row k1 and column k2 of the DCT matrix.
The general equation for a 2D (N by M image) DCT is defined by the following equation:
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Watermarking in Watermarking in Video(DCT)Video(DCT)
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Frequency DomainFrequency Domain
Watermarking signal to embedWatermarking signal to embed
Host signalHost signal
Frequency components(using DCT)Frequency components(using DCT)
EmbeddingEmbedding
ExtractionExtraction
NvvvV ,...,, 10
NxxxX ,...,, 10
NfffF ,...,, 10
iii xff
iii ffx
if = watermared singal
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Purpose of WatermarkingPurpose of Watermarking
Copyright ProtectionCopyright Protection FingerprintingFingerprinting Copy ProtectionCopy Protection Broadcasting MonitoringBroadcasting Monitoring Data AuthenticationData Authentication
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Thank you !!!Thank you !!!