1. An Algorithm for Removable Visible Watermarking
Source: Circuits and Systems for Video Technology,
Vol 16,  Issue 1,  Jan. 2006, pp. 129 – 133
Authors: Yongjian Hu, Kwong S, and Jiwu Huang.
Speakers: Hong-Hang Chang.
Date:

2. Outline Introduction Related work Proposed scheme Experimental Result
Conclusion

3. Introduction
This is a original Image. And then, we can embedded the watermark to the original image by the information of the key. So if we have the original image, watermark and the key , we can embedded the watermark to the original image. Then, how can I extract the watermark from the watermarked image. The work is similar to the embedded work , we need a watermark and a key , then we can remove the watermark from
the watermarked image soblutely.

4. HL HL LL LL LH LH HH HH Related work DWT LL2 HL2 LH2 HH2 LL HL HH LH
130
110
100
120
115
105 95 88 90 79
127
126
125
101
DWT LL
LL2
HL2 HL HL
240
210 20
-10
235
200 5 10
178
167 -2 8
253
226 1 24 LL LL
LH2
HH2 LH LH HH HH
475
410 25
431
393 -1 32 5 10 15
-20
-75
-59 -3
-16 LL HL HH LH

5. HL HL LH LH HH HH Proposed scheme LL2 HL2 LH2 HH2
LLK
LHK
HLK
HHK
LL2
HL2 HL HL
LLK
LH2
HH2
Low-Frequency Suspend LH LH HH HH LH HH HL
HL2
LH2
HH2
k = the current scale of the DWT.
K = the final scale of the DWT.
High-Frequency Suspend

6. H W X Proposed scheme (Cont.) Suppose wh= 0.25 ww= 0.75
170
150
200
140
110
120
130
100 90 H 50 40 60 70 90 80
100
110 W
Suppose wh= 0.25
ww= 0.75
170* *0.75= 80
150* *0.75= 67 .
90* *0.75= 78 80 67 95 83 88 75 98 92
100
110 90 82 77 78 X

7. HL X Proposed scheme (Cont.) Low-Frequency Suspend
Case1: take the H(1,1) for example.
X(i,j) = the mean of the coefficients corresponding ‘0’
from nearest 8 neighbors .
X(1,1)= ( )/2
=145 1 1 1 1
170
150
200
140
110
120
130
100 90
Case2: take the H(1,4) for example.
X(i,j) = the mean of all the unchanged
coefficients.
X(1,4)= ( …+77+78) / 16
= ≈92 1 1
145
150 95 92
140
110 75 98
130
100 90 82 78 HL X

8. H W H W X Proposed scheme (Cont.) Low-Frequency Suspend 1 170 150 200LH HH HL
HL2
LH2
HH2 LH HH HL
HL2
LH2
HH2
170
150
200
140
110
120
130
100 90 50 40 60 70 90 80
100
110 H W
170
150
140
120
130 90
100 50 40 70 90 80
200
150
110
120
100
140 90
130 H W X

9. Proposed scheme (Cont.)1 40 20 5
160 50 90 -1 -5
-10
-20 4
-15
-30
High-Frequency Suspend 1 1 LH HH HL
HL2
LH2
HH2
HLK
LHK
HHK
Case1: take the H(1,2) for example.
the mean of unchanged coefficients in its 8 neighbors.
Case2: take the H(3,3) for example.
the mean of unchanged coefficients in its 24 neighbors.
Case3: take the H(4,4) for example.
the mean of all unchanged coefficients . 40 5 20
160 50 90 -1 -5 3
-20 4
-15 1

10. Proposed scheme (Cont.)
High-Frequency Suspend 40 5 20
160 50 90 -1 -5 3
-20 4
-15

11. Proposed scheme (Cont.)
Retrieve A B C D E F G H I J K L M N O P
300
250
260
280 10 20 30 15 -2 -5 -1 7 5 …… a b c d e f g h i j k l m n o p
155
129 4 8
145
123 6 13
132 15 5
128
135 16 10 ……

12. Experiment result
Fig. 1 PSNR (DB) OF RECOVERED IMAGES. LR AND ILR DENOTE LEGALLY AND
ILLEGALLY RECOVERED IMAGES, RESPECTIVELY

13. Conclusion The experimental results have demonstrated
that the legally obtained image has very high
visual quality.