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A robust digital watermarking scheme for
video copyright protection
in the wavelet domain
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RADU O. PREDA, DRAGOS N. VIZIREANU
報告人:潘輝銘
Outline
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Introduction
Digital watermarking
The proposed video watermarking scheme
Experimental results
Conclusions
Introduction
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Watermarking techniques can be classified into three
categories:
spatial domain methods
simple and fast, but are not robust against attacks
transform domain methods
more robust
compressed domain methods
fast, robust, but are bound to the compression standard;
any transcoding to a different standard would destroy
Digital watermarking
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Digital watermarking 視覺上分為:
可視 (visible)
不可視 (invisible),不可視的數位浮水印技術上分為:
空間域 (spatial domain)
微調影像訊號大小或數值,置入浮水印
壓縮域 (compressed domain)
利用修改數位影片的壓縮域資料,置入浮水印
變換域 (transform domain) 轉換方法:
離散傅立葉轉換 (Discrete Fourier Transformation)
離散餘弦轉換 (Discrete Cosine Transformation)
離散小波轉換 (Discrete Wavelet Transformation)
The proposed video watermarking scheme
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The watermark is embedded in the selected wavelet
coefficients of the luminance Y of every frame of the
video.
First:conversion of the RGB color space into the YCbCr color
space
Second:using the 2D Discrete Wavelet Transform
The proposed video watermarking scheme
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YCbCr影像壓縮技術,Y表亮暗值,Cr、Cb表彩度,利用
這種格式,可將亮度與彩度分開來處理,壓縮上較有效率
轉換公式:
The proposed video watermarking scheme
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N階小波轉換
The proposed video watermarking scheme
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Embedded in of the LH1, HL1 and HH1 is very sensitive
to attacks.
In the LH3, HL3 and HH3, the perceptual quality of the
video will be significantly altered.
The proposed video watermarking scheme
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藏入 & 解碼流程:
A×B
流程圖
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The binary image matrix is transformed into a binary row
vector w of size:P A B
Hamming error correction code
b: codeword bits length
b : dataword bits length
Size of the resulting watermark
A
1 0 0 1 1 0
B
w
b
w vector: P P
b
w
1
0
0
1
1
0
P
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Spread – spectrum technique 將浮水印訊號打散,嵌入於
影像之離散小波係數當中。當影像遭受惡意攻擊時,仍能
正確地擷取出浮水印訊號。
A secret key K as seed: S {s j | s j {0,1}, j 0,1,..., G} is
generated using the Mersenne–Twister algorithm
Mersenne-Twister algorithm 為一種假的亂數,比起rand( ) 有更好的
亂度,能產生的亂數序列週期非常長。
rand( ) 範圍 1~32727 Mersenne-Twister algorithm (2
19937
的週期,亂數很難「重複」
1) / 2
流程圖
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The corresponding spread spectrum sequence:
[ s1 , s2 ,..., sG ], if w(i ) 0
w(i)
, i 1,..., P
[ s1 , s 2 ,..., s G ], if w(i) 1
w
1
0
0
1
1
0
w s1 s 2 .... s G
P
w s1 s2 .... sG
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Videos of resolution M × N, selected wavelet coefficients
of a frame :
C 3
MN
, L3
2 ( L 1)
2
C FC , F is the number of video frames
C F
G
, [ ] is the integer part operator
P
the binary sequence S of size G
流程圖
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以區塊內之量化值來藏入bit(1 or 0)
dw
block
even embed “0”
quantization
value
odd embed “1”
d
d
1, if x 0
d 2q q w sign d 2q , sign ( x)
2q
2q
1, if x 0
w
d : original wavelet coefficient
d w : watermarked wavelet coefficient
q : quantization step
流程圖
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The secret key K provides the information for the size G
of the watermark.
The binary sequence S is extracted using:
d wj
, j 1,..., G
s j mod ulo2 ROUND
q
流程圖
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Using the 64 bit seed from the secret key K the binary
sequence S 0 corresponding to a ‘‘0” is generated.
Every extracted sequence S(i), i = 1, ... , P0 the
corresponding watermark bit :
0, if
w(i )
1, if
S (i) S
G
j 1
k
G
j
2
, j 1,..., G
G
S j (i ) S0 j (i )
2
i 1
0 j (i )
Watermark bitstream w0 of size P0 is error corrected.
The watermark
w of size P is obtained.
Experimental results
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They are in RGB uncompressed avi format, of 1 s
duration, resolution 352 × 288 and frame rate 30
frames/s.
The watermark is a binary
image of size 64 × 16 pixels
Experimental results
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PSNR:(Peak Signal to Noise Ratio) 經過影像壓縮後,
參考PSNR值來認定影像品質,PSNR值越大,代表失真
越少。
BER:(Bit Error Rate) 衡量數據在受攻擊後,其精確性的
指標,BER值越小,表示過程中誤碼率越低。wout 為析取
浮水印,win 為原始水印,P為浮水印總大小。
Experimental results
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Used nine attacks to test the robustness:
(1) Blurring using blocks of 2 × 2 pixels.
(2) Brightening by adding Y0 = 5 to the luminance of every pixel.
(3) Adding Gaussian noise of mean 0% and variance 0.05%.
(4) Median filtering using a 3 × 3 pixel neighborhood.
(5) Adding“salt and pepper”noise with density d = 0.05%.
(6) Frame averaging, where the current frame.
f (i )
f (i 1) f (i ) f (i 1)
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(7) Frame removal – three random frames were removed.
(8) JPEG compression of every frame with quality factor Q = 70.
(9) MPEG-2 compression at 4 and 2 Mbps.
Experimental results
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Experimental results
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Experimental results
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PSNR has values 45 ~ 49 dB.
The watermarked videos appear visually identical to the
original ones.
Experimental results
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Conclusions
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The proposed algorithm achieves good resilience again a series of different
attacks in the spatial, temporal and compressed domain.
Further improvements of the algorithms will be made for a better protection
against these types of attacks and also against other attacks, such as
geometric distortions like scaling, translation and rotation.
Video watermarking using authentication and can also hidden the message.