copyright protection for images on mobile devices.pdf

5/24/2018 Copyright Protection for Images on Mobile Devices.pdf

Copyright Protection for Images on Mobile Devices

Raffaele Pizzolante, Bruno Carpentieri

Dipartimento di InformaticaUniversit degli Studi di Salerno

I-84084 Fisciano (SA), Italy

[email protected], [email protected]

AbstractThe rapid diffusion of mobile devices (telephones,

smart phones, tablets, etc.) has brought new advanced features

developed specifically for these devices. For example it is now

possible to publish directly the pictures obtained by the

integrated camera of a smart phone to our social network

accounts, or to image hosting services, etc.. It is therefore

important to have tools on the mobile devices that can prove

the ownership of the pictures and to use them before

publishing the images. A common approach to guaranteeownership of digital images or videos is to use Digital

Watermarking techniques. We have developed a tool for

portable devices based on Android OS, that permits to add a

visible or invisible watermark to images. In this paper we

discuss this tool, and we experimentally prove its robustness.

Keyword: Mobile Device Security; Digital Watermarking;

Copyright Protection

I. INTRODUCTIONDuring the last few years mobile devices, such as tablets,

smart phones, etc., have increased their potentialities in

terms of hardware (i.e. display resolution, processor speed,

etc.) and software.The built-in operating systems are specifically designed

for these devices (for example Android, iOS, Symbian, etc.)

and implement many advanced features.

Moreover, there are a large number of third-party

applications (also called Apps) that can be installed on these

devices.

These mobile devices are currently used for a wide range

of purposes: for example for internet browsing, for sending

and receiving email, Multimedia Message Service (MMS)

message, and many others.

It is also possible to directly publish the photos, obtained

by the integrated camera of the portable device, to social

networks, image hosting services, and so on.These possibilities introduced by the advanced features ofthe portable devices have prompted us to focalize our

attention to the security problem. An important aspect

related to mobile devices security is to guarantee the

ownership of an image, before publishing or sending the

image to another party. The classical solution is to embed in

the image watermarking information related to the producer.This technique is usually referred to as Digital

Watermarking.

There are, substantially, two types of digitalwatermarking approaches: visible or invisible

watermarking.

In the first case, the information is visible in the picture.

Generally the watermark is a text (as in Figure 1) or a logo

(as in Figure 2).Invisible watermark instead modifies a few small features

of the multimedia data and it is not directly visible to theend user. In order to verify the property, the owner has an

algorithm that can extract the invisible watermark to prove

ownership. For this latter type of watermarking there are

many methods for embedding the information: for examplethe spread-spectrum methods, the amplitude methods, etc..

In this work we propose a tool for portable devices that

embeds a visible or an invisible digital watermarking into an

image.

The proposed tool is for Google Android OS ([1]). It

takes as input a picture and a string and it gives as output the

image with visible or invisible digital watermarking.

Figure 1. An example of an image affected by visible watermarking(watermark is the string SEA).

Figure 2. An example of an image affected by visible watermark

(watermark is the logo of the University of Salerno).

The remainder of this work is organized as follows: in

Section II we discuss the backgrounds of Digital

Watermarking.

2012 Sixth International Conference on Innovative Mobile and Internet Services in Ubiquitous Computing

978-0-7695-4684-1/12 $26.00 2012 IEEE

DOI 10.1109/IMIS.2012.73

585


In Section III we present our tool, based on Android OS,

and focus on the visible and invisible watermarking

capabilities of this tool.In Section IV we report the experimental results achieved

by the tool, In Section V we present our conclusions and

highlight future work directions.

II. DIGITAL WATERMARKINGDigital Watermarking is a technique that is used to insert

hidden data into digital content, such as images, videos, etc.If a digital file is affected by one or more watermarks, then

the hidden information will be also carried in its copies.

An important application of digital watermarking is for

copyright protection. In this case, the digital watermarking

is used to prevent unauthorized copy of the digital media.

There are substantially two types of digital watermarking:

Invisible watermarking Visible watermarkingIn the first case the information are embedded into digital

media by modifying some features of the data. These

modifications are not perceptible by the end user.There are different methods for embedding a digital

invisible watermarking:

spread-spectrum quantization amplitude modulationThe method based on spread-spectrum [8-9] consists in

an additive modification on the image spectral signal.

The quantization [10] embedding methods obtains the

marked signal by quantizing the original spectral signal.

The amplitude modulation method embeds the watermark

into the spatial domain.

In digital visible watermarking the watermarking

information in the digital picture or video is visible to theend user.

Usually the watermarking is a text or a simple logo,

which identifies the owner of the multimedia data. For

example the logo which identifies a TV channel can beconsidered as visible watermark. This type of digital

watermark is often used also for the pictures and videos on

the Web, when the owner wants immediately inform the end

user of the property information regarding the digital object.

III. AN ANDROID OSWATERMARKING TOOLWe have developed a tool, for Google Android OS (2.2

or later), that reads an image (on the internal storage or on

the external data storage, such as SD card, an USB pen drive

and so on), and affects the image with a digital invisiblewatermark or with a digital visible watermark.

The supported image formats are JPG, PNG, BMP, etc.

A. Digital Visible WatermarkingIf the user chooses to embed a digital visible

watermarking, the tool takes as input a string that will be

inserted as the watermark, and it produces as output the

visible watermarked image.

Our tool permits to configure a few options: the size of

the font, the typeface (Serif, Sans Serif or Random) of the

font, the number of repetitions and the color.The implemented algorithm converts the string of the

watermark in a bitmap image and then it merges the bitmap

obtained with the input image in a random positions. The

number of positions selected depends on the repetitions

given by the user.Figure 3 shows the User Interface (UI) of the tool for the

configuration of the options on the SDK emulator ([2-4])

with screen resolution of 320x640.

Figure 3. Configuration panel of the tool for digital visible watermarking

on the Android SDK Emulator.

Figure 4 shows a preview of the image Lena affected

by a visible watermark by the tool on the Android SDKEmulator with HVGA screen resolution (320x480), in

portrait mode.

Figure 4. Preview of the Lena image affected by a digital visible

watermark on Android SDK emulator, in portrait mode.

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Figure 5 shows another preview of the watermarked

image, obtained by the tool, on Android SDK emulator with

HVGA screen resolution, in landscape mode.

Figure 5. Preview of the Lena image affected by a digital visiblewatermark on Android SDK emulator, in landscape mode.

As we can see in the Fig. 4 and Fig. 5, the tool permits a

preview of the watermarked image on the smartphone

display. Moreover, the tool permits to save the result in user

defined position on the device.

Figure 6. The resulting image with the visible watermark produced by the

tool.

Figure 6 shows the resulting image.

B. Digital Invisible WatermarkingThe tool allows to produce a digital invisible

watermarking too.The implemented algorithm is based on a modified

version of the algorithm proposed by Langelaar et al. [7]

and it takes as input the source image, aseed, a threshold T,

the watermark string, and the path of the output image.

The seed means an ID (such as numeric PIN) that is usedto embed the watermark, and in second instance for extractit from the watermarked image. The threshold (a real

number) indicates the robustness of the watermark that will

be embedded.

Algorithm 1 reports the pseudo-code of the algorithm for

embedding the digital visible watermark.

1. The image in RGB domain is converted to the YUVdomain.

2. The watermark string is converted to a matrix of bits.Each character is converted in a 5x8 matrix of bits

(see the example in Fig. 7).

The resulting matrix will be embedded in the

original image line-by-line from left-top corner.

3. A blockBof 8x8 pixels is pseudo-randomly selectedfrom the image to embed one bit of the watermarkstring.

4. A fixed binary pseudo-random pattern of the samesize ofBis generated.

5. I0, I1and Dare calculated. I0and I1are the obtainedby calculating the averages of the luminance values

inB, respectively where the random pattern is 0 andwhere the random pattern is 1. Dis the difference I1

I0.

6. B is a reduced quality block obtained by applyingthe quantization (Fig. 8 shows the quantization

coefficients matrix used) and the 8x8 DCT

transform.7. I0, I1 and D are calculated. I0 and I1 are the

obtained by calculating the averages of the

luminance values in B, respectively where the

random pattern is 0 and where the random pattern is

1. Dis the difference I1 I0.8. If the bit to embed has value 1 the go to step 11.9. In order to embed the bit with value 0, the binary

pseudo-random pattern is subtracted from the block

B, if Dand Dare greater than the threshold -T. The

steps 6-8, and 10 are repeated iteratively until both

differences are less or equal -T. Go to step 12.

10. In order to embed the bit with value 1, the binarypseudo-random pattern is added from the blockB, if

Dand Dare less or equal than the threshold T. Thesteps 6-8, and 11 are repeated iteratively until both

differences are greater than T.

11. The steps from 4 to 11 are applied to all pseudo-randomly selected blocks until all bits of the

watermark string are embedded.

12. The image in YUV domain is converted to the RGBdomain.

Algorithm 1. The pseudo-code of the algorithm for embedding the digitalinvisible watermark based on the algorithm proposed by Langelaar et al.[5]

Figure 7. Example of conversion from the character e to the matrix ofbits composed by 5 x 8 bits (40 bits). The white cells are represented by the

value 0 and the black cells are represented by 1.

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Figure 8. The 8x8 matrix of coefficients used for the quantization by the

implemented algorithm.

Algorithm 2 reports the algorithm for the extraction of

the digital invisible watermarking.

1. The image in RGB domain is converted to the YUVdomain.

2. A blockBof 8x8 pixels is pseudo-randomly selectedfrom the image to read one bit of the watermark

string.3. A fixed binary pseudo-random pattern of the same

size ofBis generated.

4. I0, I1and Dare calculated. I0and I1are the obtainedby calculating the averages of the luminance values

in B, respectively where the random sequence is 0

and where the random sequence is 1. D is the

difference I1 I0.

5. If D> 0 then the embedded bit has value 1 else theembedded bit has value 0.

6. The steps from 2 to 5 are repeated until all the bitsare extracted.

7. The extracted bits are converted to the matrix of thebits and the in the bitmap of the watermark string.Algorithm 2. The pseudo-code of the algorithm for the extraction of the

digital invisible watermark.

In both algorithms the seed is used for the generation of

all pseudo-random sequences and patterns.

The watermarked image can be stored in JPEG format orPNG format.

In the first case it is possible to set the compression

quality.

In the second case the produced image is compressed in

lossless mode with the PNG integrated algorithm providedby Android OS.

Figure 9 shows a screenshot of the configuration panel of

the digital invisible watermarking.The next screen of the tool shows the positions of the

blocks affected by the digital invisible watermark.

Figure 10 shows a picture of this screen.The white part of the image is the part that will not

modified by the algorithm.

The red blocks instead indicate the blocks that will

embed the value 1 and the blue blocks indicates the blocks

that will embed the value 0.

Figure 9. Configuration panel of the tool for digital invisiblewatermarking on the Android SDK Emulator.

Figure 10. An example of the screen that shows the blocks affected by the

digital invisible watermark. The red blocks indicate the blocks that embedthe value 1 and the blue blocks indicate the blocks that embed the value 0.

IV. EXPERIMENTAL RESULTSIn this section we report the experimental results

achieved by the tool with a test set of RGB images

composed of sixteen images with 24 bits per pixel in RGBformat.

The images are online available for research use from

The USC-SIPI Image Database [5] in the Miscellaneous

section [6].

All the images are in TIFF format, we have converted

they in the original BMP format to use them with theintegrated image processing library provided by Android

OS.

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Table I lists the test set images. The first column

indicates the filename, the second column indicates a short

description, the third column indicates the resolution and thefourth column indicates the size in kilobytes (KB).

Filename Description Resolution Size (KB)

4.1.01 Girl (1) 256x256 1924.1.02 Couple 256x256 192

4.1.03 Girl (2) 256x256 192

4.1.04 Girl (3) 256x256 192

4.1.05 House 256x256 192

4.1.06 Tree 256x256 192

4.1.07 Jelly beans (1) 256x256 192

4.1.08 Jelly beans (2) 256x256 192

4.2.01 Splash 512x512 768

4.2.02 Girl (Tiffany) 512x512 768

4.2.03 Mandrill (or Baboon) 512x512 768

4.2.04 Girl (Lena or Lenna) 512x512 768

4.2.05 Airplane (F-16) 512x512 768

4.2.06 Sailboat on lake 512x512 768

4.2.07 Peppers 512x512 768

house House 512x512 768Table I. The used test set of images available on [6].

Table II and Table III report the results in terms of

percentage of incorrect bits resulting respectively from the

extraction of the invisible watermark with string Hello

(composed by 200bits) and the string University

(composed by 400 bits).

The first column indicates the image, the second column

indicates the threshold T. The third, fourth and fifth columns

indicate respectively the percentage of the incorrect bits

obtained from the extraction of the watermark where the

image is compressed with JPEG (with integrated algorithm

provided by the Android OS) with respectively 100%, 75%,

50% and 30% of quality factor and the compression ratio

achieved.

Image T JPEG

100%/

C.R.

JPEG

75%/

C.R.

JPEG

50%/

C.R.

JPEG

30%/

C.R.

4.1.01 15 0%/

3.09

0.5%/

17.80

2.5%/

27.46

7%/

37.29

4.1.02 15 1%/

3.22

3.5%/

18.36

7.5%/

27.56

11%/

37.48

4.1.03 15 0%/

3.66

0%/

24.90

0.5%/

37.96

3.5%/

50.50

4.1.04 15 0%/

3.16

0.5%/

16.92

2.5%/

25.54

9.5%/

34.74

4.1.05 15 0%/3.13

0%/17.15

2%/26.43

5%/36.22

4.1.06 15 0%/

2.52

0%/

11.60

0.5%/

17.56

3.5%/

23.60

4.1.07 15 0%/

3.60

0%/

23.98

1%/

35.63

4%/

46.87

4.1.08 15 0%/

3.32

0%/

19.18

1%/

28.28

8%/

37.47

4.2.01 15 2.5%/

3.51

2.5%/

23.34

3.5%/

37.19

7%/

53.09

4.2.02 15 0%/

3.26

1.5%/

20.36

2.5%/

33.16

6%/

47.43

4.2.03 15 0%/2.52

0%/10.10

0.5%/15.46

4%/21.68

4.2.04 15 0%/

3.20

0%/

19.84

3.5%/

31.41

9%/

43.63

4.2.05 15 0%/

3.32

0%/

19.46

1%/

29.66

4%/

40.054.2.06 15 0%/2.71

0%/14.60

2%/22.62

10%/31.34

4.2.07 15 0%/

3.02

0.5%/

18.26

3%/

29.19

6.5%/

41.05

house 15 0%/

3.01

0%/

15.95

0.5%/

23.86

3.5%/

32.37

Table II. Achieved results of the watermark extraction of 200 bits(obtained by the string Hello).

Image T JPEG

100%/

C.R.

JPEG

75%/

C.R.

JPEG

50%/

C.R.

JPEG

30%/

C.R.

4.1.01 15 0.25%/

2.98

1%/

16.61

2.75%/

25.95

6.75%/

35.794.1.02 15 1%/

3.112.75%/17.30

7.25%/26.49

12%/36.33

4.1.03 15 0%/3.39

0%/20.86

0%/32.93

3.5%/45.52

4.1.04 15 0%/3.03

0.25%/15.74

3%/24.20

7.75%/33.43

4.1.05 15 0%/

2.98

0%/

15.84

0.25%/

24.53

2.25%/

34.18

4.1.06 15 0%/

2.46

0%/

11.09

0.25%/

16.99

3.5%/

23.04

4.1.07 15 0%/3.33

0%/19.86

0%/31.11

3.75%/42.69

4.1.08 15 0%/3.11

0%/17.07

0.5%/26.06

4%/35.24

4.2.01 15 1.5%/

3.46

1.5%/

22.62

3.25%/

36.13

7.25%/

51.664.2.02 15 0.25%/

3.221.5%/19.92

3.25%/32.42

6.25%/46.57

4.2.03 15 0%/

2.25

0%/

10.06

1%/

15.14

4%/

21.62

4.2.04 15 0%/

3.17

0%/

19.41

1.75%/

30.81

6.75%/

43.00

4.2.05 15 0%/

3.28

0.25%/

19.97

1.5%/

29.10

4%/

39.41

4.2.06 15 0%/

2.69

0%/

14.37

1.5%/

22.31

6.75%/

30.97

4.2.07 15 0.25%/2.99

0.75%/17.89

1.5%/28.68

7%/40.42

house 15 0%/2.97

0%/15.62

0.75%/23.49

6.5%/31.99

Table III. Achieved results of the watermark extraction of 400 bits

(obtained by the string University).

Even though there is a percentage of errors obtained fromthe extraction process when the compression factor of the

JPEG algorithm is low (i.e. 50% and 30%) however is

possible to easily distinguish the string of the watermark.

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Figures 11(a), 11(b), 11(c) and 11(d) show respectively

the results of the extraction of the watermark of 400bits

(obtained by the string University) from the image Girl

(3) (filename: 4.1.04) compressed with JPEG respectively

with quality factor of 100%, 75%, 50% and 30%.

The watermark string is extracted with percentage of

errors respectively of 0% (0 bit), 0.25% (1 bit), 3% (12 bits)

and 7.75% (31 bits).

Figure 11. The results of the extraction of the watermark of 400 bits(obtained by the string University) from the image Girl (3) (filename:

4.1.04) respectively when the compression with JPEG has quality factor of100% (a), 75% (b), 50% (c) and 30% (d).

V. CONCLUSIONS AND FUTURE WORKSThe continue evolution of the portable devices prompts

us to investigate on the security issues.In particular, in this work it is considered the possibilities

to guarantee the ownership of an image directly through themobile devices.

We have proposed a tool for Google Android OS thatpermits to add an invisible or visible watermark into animage.

Future work will consider the possibility to producewatermarked images automatically before sending email orMMS messages or publishing it.

Moreover, future work will also include theimplementation and testing of different approaches fordigital invisible watermarking.

REFERENCES[1] Android Home Page [Online]. Available: http://www.android.com[2] Android Developers [Online]. Available:

http://developer.android.com

[3] Android SDK Web Page [Online]. Available:http://developer.android.com/sdk/

[4] Android Developers Blog [Online]. Available : http://android-developers.blogspot.com/

[5] SIPI Image Database [Online], Available :http://sipi.usc.edu/database/database.php

[6] SIPI Image Database Miscellaneus [Online], Available :http://sipi.usc.edu/database/database.php?volume=misc

[7] G. C. Langelaar, J.C.A. van der Lubbe, and J. Biemond, CopyProtection for Multimedia Data based on Labeling Techniques, 17thSymposium on Information Theory in the Benelux, 1996.

[8] Yu-Pin Wang, Mei-Juan Chen, Po-Yuen Cheng, "Robust imagewatermark with wavelet transform and spread spectrum techniques,"Signals, Systems and Computers, 2000. Conference Record of theThirty-Fourth Asilomar Conference on , vol.2, no., pp.1846-1850vol.2, 2000.

[9] Qiujuan Liang, Zhizhong Ding, "Spread Spectrum Watermark forColor Image Based on Wavelet Tree Structure," Computer Scienceand Software Engineering, 2008 International Conference on , vol.3,no., pp.692-695, 12-14 Dec. 2008

[10] Cong Jin, Yan Chao, Xiao-Liang Zhang, "Semi-Fragile WatermarkBased on Adaptive Quantization for Image Content Authentication,"E-Business and Information System Security, 2009. EBISS '09.International Conference on , vol., no., pp.1-5, 23-24 May 2009.

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