Information Hiding in Image and Audio Files
2007-2010
CHAPTER 3
INFORMATION HIDING USING LEAST
SIGNIFICANT BIT METHOD
The Least Significant Bit (LSB) insertion method is a common,
simple approach to embedding information in a graphical image file.
In LSB insertion method the LSB of every pixel is replaced by every
message bit. There is 50 % chance that the message may match
with the LSB‟s of the Cover image. Thus only 50 % LSB‟s are likely
to change. Also, the change occurs only in the bit which is least
significant, thus keeping the other more significant bits unaltered.
Therefore, this does not affect the original image perceptibility.
Hence it is a very popular technique. However, it is extremely
vulnerable to attacks. Any image manipulations such as cropping,
intensity
changes
for
any
enhancements
such
as
contrast
stretching, histogram equalization, addition of noise etc will destroy
the embedded message.
The techniques other than LSB technique are complicated, although
they are robust to most attacks. LSB technique can therefore be
used wherever we want to store confidential information on a
standalone PC or one which is shared among several users. LSB
technique can be used to store personal data such as ATM PIN,
Credit card details, salary statement, income tax data, passport
information etc in an imperceptible way. So, wherever this kind of
information is to be preserved in a manner that only legitimate user
should be able to retrieve it whenever needed, by simple ways, LSB
is a better solution.
Least Significant Bit (LSB) encoding is the easiest of the techniques
used for embedding secret or confidential information in digital
41
Information Hiding in Image and Audio Files
2007-2010
images. For a gray scale bitmap (BMP), using the LSB of each byte
(8 bits) in an image, a secret message of size 1/8 th of the Cover
image can be stored. This can be easily done by directly substituting
every bit of the secret message into every LSB.
For a 24 bit color image as the cover image, since there are 3 bytes
for every pixel, 3 bits of data can be stored in each pixel, so the
capacity to store increases by 3 times thus making it 3/8 of the
cover image size. If the message to be embedded is a text message
a secret message of size 1/7th of the grayscale cover image can be
stored and in a 24 bit color image as cover a text message of size
3/7 can be embedded.
The confidential information which is embedded in the Cover image
can be an image (grayscale, binary or color image), text or even
audio. As the type and size of confidential information varies, the
embedding capacity varies for a particular type of Cover used. LSB
technique can be used either by directly replacing the Cover LSB‟s
by the Secret information bits, or to add one more level of security,
it can be encrypted and then inserted into the LSB‟s of the Cover.
3.1 Using 2 / 3 / n LSB’s Technique
The technique [79] implemented in this section not only replaces
the LSB, but the LSB is modified by taking into consideration the
other bits of the Cover and the message bit as well. Advantage of
this method is it adds one more level of security, by encrypting the
message bits before embedding with just a slight increase in the
encoding / decoding complexity and Cover capacity remains the
same as LSB substitution, accuracy of retrieval is 100%, and good
perceptual transparency of cover image is achieved.
42
Information Hiding in Image and Audio Files
2007-2010
3.1.1 Embedding Algorithm
Extract RGB components of pixel intensity values of message and
the cover image if 24 bit color images are to be used else for a
grayscale image every byte is the intensity of every pixel. In case
text message is to be embedded, then their ASCII codes have to be
considered. The procedure given below is by considering 24 bit color
images. Take the successive R, G, and B component values of pixels
and convert them into array of values for messages and the cover
image. Convert every decimal value into 8 bit binary equivalent for
cover and message images. Every message bit is embedded into
LSB‟s of the cover image after processing. Processing is done as
follows:
a) LSB 2 Method:
If the message bit to be embedded is 0, then adjust the LSB
such that the XOR operation on LSB and next to LSB is 0 and
if the message bit to be embedded is 1, then adjust the LSB
such that the XOR operation on LSB and next to LSB is 1 as
shown in the Table 3.1 below.
Table 3.1 Truth Table for LSB 2 Bit Method
Next to LSB
LSB
Message Bit
LSB Adjusted
0
0
0
No Change
0
1
0
0
1
0
0
1
1
1
0
No change
0
0
1
1
0
1
1
No change
1
0
1
No change
1
1
1
0
Remark: There are 50 % chances that there will not be any change in the
Stego.
b) LSB 3 Method: If the message bit to be embedded is 1, then
the LSB is adjusted such that the XOR operation on LSB, next
43
Information Hiding in Image and Audio Files
2007-2010
to LSB and next to next to LSB is 0. And if the message bit to
be embedded is 1, then adjust the LSB such that the XOR
operation on LSB next to LSB and next to next to LSB is 1 as
shown in the Table 3.2 below.
Table 3.2 Truth Table for LSB 3 Bit Method
Next
to
Next LSB
0
Next to
LSB
0
0
Message
Bit
0
LSB
Adjusted
No change
0
0
1
0
0
0
0
1
0
0
1
1
1
0
No change
1
0
0
0
1
1
0
1
0
No change
1
1
0
0
No change
1
1
1
0
0
0
0
0
1
1
0
0
1
1
No change
0
1
0
1
No change
0
1
1
1
0
1
0
0
1
No change
1
0
1
1
0
1
1
0
1
1
1
1
1
1
No change
LSB
The message embedding in the cover image is over.
3.1.2 Retrieving Algorithm
The message retrieving is done as per the algorithm given below
a) Extract Red, Green and Blue Components of pixel intensity
values of Stego image.
b) Take successive Red, Green and Blue component values of
pixels and convert them into array of values for message and
Stego image.
c) Convert every decimal value into 8 bit binary equivalent for
Stego image.
d) Retrieval of the message bit is done by using the XOR
operation on the LSB and Next to LSB.
i. If it is 1 then message bit is 1.
ii. If it is 0 then message bit is 0.
44
Information Hiding in Image and Audio Files
2007-2010
e) If during embedding the LSB 3 method is used then retrieval
is done by performing XOR operation on LSB, next to LSB and
Next to Next to LSB‟s.
i. If the result of XOR operation is 0, it means the decoded
message bit value is 0 and
ii. If the result is 1, it means that the decoded message bit
value is 1.
f) Convert every 8 bits to form a byte whose decimal value is
the pixel intensity if the message embedded is a grayscale
image otherwise this decimal value forms the intensity of Red
component of the first pixel of the Secret image, if the
message embedded is a 24 bit color image. If the message
that is embedded is a text message then after every 7 bits are
retrieved convert them into decimal which forms the ASCII
code of the 1st character. In this manner these steps are
continued till the full message is retrieved.
g) In case of 24 bit, every byte forms either the Red, Green or
Blue component of the message pixels in sequence. Take 3
bytes and group them as 3 RGB components of a 1 pixel.
Perform this step for the full message.
The message retrieval is over.
Instead of only 2 or 3 LSB‟s this method can be extended till all the
8 bits of the cover image are considered to encrypt the message bit,
and then in that case the decryption will be done considering 2, 3
till 8 bits of the Cover image respectively.
3.2 Considering Parity
In addition to the above encryption method, one more simple
method for encryption is suggested, which uses parity as a key for
45
Information Hiding in Image and Audio Files
2007-2010
embedding. The embedding and retrieval is to be done as given
below.
3.2.1 Embedding Algorithm [80]:
Adjust the LSB of the byte of the Cover so that it is even parity after
embedding if the message bit to be embedded is 0 and adjust the
LSB of the byte of the Cover so that it becomes odd parity after
embedding of if the message bit to be embedded is 1. This is done
till the embedding of all message bits is over.
3.2.2 Retrieval Algorithm:
For retrieving the message the Stego image is taken. The parity of
every byte is checked. If the parity is even that means the message
bit is 0 and if the parity is odd it means the message bit is 1. The
role of odd and even parity is interchangeable.
In this way after 8 such message bits are retrieved they are
converted to decimal and this decimal number becomes the
intensity value of the first message pixel for grayscale image or Red
component of the first pixel if the message is 24 bit color image. If
the message embedded was a text message, then after every 7 bits
of message are retrieved they are converted to decimal and this
decimal value is the ASCII code of the 1st character in the message.
This procedure is repeated until the full message is retrieved, and
the message image is formed or the full text message is retrieved.
3.3 Experimental Results
For Experimental purpose, 2 sets (24 bit colour) of fifteen cover
images each, one set of size 512 X 512 and the other of size 1024 X
1024 for all the three methods (LSB 2, LSB 3 and Parity) are used.
46
Information Hiding in Image and Audio Files
2007-2010
Ten secret message images and 4 Microsoft word documents are
used for embedding. The 10 message images are 128X128, 24-bit
color images and out of the four Microsoft word documents 1 st is the
speech delivered by Dr. A. P. J. Abdul Kalam in Hyderabad which is
3 pages Microsoft Word document of 1262 words (6764 characters),
2nd message is the famous Abraham Lincoln‟s letter to his son‟s
teacher which is 1 page letter of 396 words (1988 characters), the
3rd is a 7 page Microsoft word document which is the 5 th chapter
from
„The Tale of two cities‟ with 4171 words, and 23496
characters, and the 4th message is the front page of my Synopsis
Report with NMIMS logo which is a 1 page Microsoft Word document
with 78 words and 486 characters.
All cover images, message images and text messages are given in
appendix. The Experimental results obtained for some of the Cover
images, Stego Images are shown in Figure 3.1 (a-d) to 3.8 (a-d).
Figure 3.1(a) - Figure 3.4(a) represent 24 bit cover images of size
512 X 512. Figure 3.1(b) - Figure 3.4(b) represent their stego
images using LSB 2 XOR method, Figure 3.1(c) - Figure 3.4(c)
represent their stego images using LSB 3 XOR method, Figure
3.1(d) to Figure 3.4(d) represent their stego images using LSB
parity method respectively with message image 1 embedded in it.
Figure 3.5(a)-3.8(a) are Cover images of size 1024 X 1024. Figure
3.5(b) - 3.8(b) are Stego images using LSB 2 bit XOR algorithm
Figure 3.5(b)- 3.8(b) are Stego images using LSB 3 bit XOR
algorithm and Figure 3.5(d)-3.8(d) are Stego images using LSB
parity method with message 1 embedded in it.
Figure 3.9 (a) shows the message image 1 which is used as input
message. Figure 3.9(b) - Figure 3.9(d) shows the retrieved
message from Stego image which are shown in Figure 3.1(b)-Figure
47
Information Hiding in Image and Audio Files
2007-2010
3.1(d). The message retrieval is 100% for all three methods and so
message retrieved from only 1 Stego image for all three methods is
shown over here
Figure 3.1(a)
Figure 3.1(b)
MSE = 0.252
Figure 3.1(c)
MSE = 0.251
Figure 3.1(d)
MSE = 0.250
Figure 3.2(a)
Figure 3.2(b)
MSE = 0.251
Figure 3.2(c)
MSE = 0.251
Figure 3.2(d)
MSE = 0.250
Figure 3.3(a)
Figure 3.3(b)
MSE=0.243
Figure 3.3(c)
MSE = 0.256
Figure 3.3(d)
MSE = 0.248
Figure 3.4(a)
Figure 3.4(b)
Figure 3.4(c)
Figure 3.4(d)
MSE=0.252
MSE = 0.250
MSE = 0.238
Stego images for
LSB2 with
message1
Stego images for
LSB3 with
message1
Stego images for
LSB Parity with
message1
Cover images of
size 512 X 512
48
Information Hiding in Image and Audio Files
2007-2010
Figure 3.5(a)
Figure 3.5(b)
MSE = 0.063
Figure 3.5(c)
MSE = 0.063
Figure 3.5(d)
MSE = 0.060
Figure 3.6(a)
Figure 3.6(b)
MSE=0.063
Figure 3.6(c)
MSE = 0.062
Figure 3.6(d)
MSE = 0.062
Figure 3.7(a)
Figure 3.7(b)
MSE=0.060
Figure 3.7(c)
MSE=0.065
Figure 3.7(d)
MSE=0.065
Figure 3.8(a)
Figure 3.8(b)
MSE=0.062
Stego images for
LSB2 with
message1
Figure 3.8(c)
MSE=0.061
Stego images for
LSB3 with
message1
Figure 3.8(d)
MSE=0.062
Stego images for
LSB Parity with
message1
Figure 3.9(b)
Message retrieved
from Stego 3.1(b)
Figure 3.9(c)
Message retrieved
from Stego 3.1(c)
Figure 3.9(d)
Message retrieved
from stego 3.1(d)
Cover images of
size 1024 X 1024
Figure 3.9(a)
Original Message
49
Information Hiding in Image and Audio Files
2007-2010
A new parameter AFCPV is introduced which gives a better feel of
perceptibility as compared to MSE.
Since Perceptibility is one of the major aspects of steganography,
the parameter introduced gives a measure to this aspect. Smaller
the value of AFCPV, better is the imperceptibility
AFCVP 
where
 (| f
- fx, y | / fx,y )
x,y
Mx N
fx,y :original image,
f‟x,y : stego image.
M: number of rows
N : number of columns
in the input images
For performance evaluation of different methods the parameters
used are Mean Squared Error (MSE), Peak Signal to Noise Ratio
(PSNR),
Average
Fractional
Change
in
Pixel
Value
(AFCPV),
Percentage of Bytes Changed, Percentage change in LSB‟s (from
Zero to One and One to Zero.
Mean Square Error (MSE)
The MSE represents the cumulative squared error between the
decompressed/reconstructed and the original image. MSE between
two images can be computed as,
 I
1
MSE 
(m, n)  I2(m, n)
M,N
MN
where
50
2
Information Hiding in Image and Audio Files
2007-2010
M and N : number of rows and columns in the input images,
respectively.
I1 (m,n) :image pixel value at position (m,n) in the original image
I2(m,n) is the image pixel value at position (m,n) in the stego
image.
Lesser the MSE, better the quality of reconstructed image.
Peak Signal to Noise Ratio (PSNR)
PSNR represents a measure of the peak error. The higher the PSNR,
the better the quality of the decompressed or reconstructed image.
PSNR is computed as,
 R2 

PSNR  10 log 10 

MSE


R is the maximum fluctuation in the input image data type. For
example, if the input image has a double-precision floating-point
data type, then R is 1. If it has an 8-bit unsigned integer data type,
R is 255.
Percentage of Bytes Changed (PBC)
Another useful parameter which is used to measure the quality of
the reconstructed image is Percent of Bytes changed [35]. Lesser
the value, better the reconstructed image.
51
Information Hiding in Image and Audio Files
2007-2010
Percentage of Bytes changes is computed as
 No. of Bytes changed
 * 100
P  
 Total No. of Bytes 
Retrieval Accuracy (RA)
This parameter is used to measure the retrieval accuracy of the
secret message from stego image.
 No. of correct Bytes re cov ered
 * 100
A  
Total No. of Bytes


(3.13)
The Tables and Charts for the all the algorithms are shown below.
Table 3.3 shows the values of MSE, PSNR, AFCPV, Percentage of
bytes changed, Changes (0 to 1) in percent and Changes (1 to 0) in
percent
for
embedding
a
message
image
of
an
ATM
Card
(Message1) in Cover images 1 -15 of size 512 X 512 using LSB 2-bit
Method. The last row shows their average values for Cover images
1- 15.
Table 3.4 shows the average values of MSE, PSNR, AFCPV,
Percentage of bytes changed, Changes (0 to 1) in percent and
Changes (1 to 0) in percent for Cover images 1 - 15 of size 512 X
512 using LSB 2-bit Method with 10 different message images
embedded in them.
52
Information Hiding in Image and Audio Files
2007-2010
Table No 3.3 Values of MSE, PSNR, AFCPV, bytes changed , Changes (0 to 1) in
percent and Changes (1 to 0) in percent for embedding a message image of an
ATM Card (Message1) in Cover images 1 -15 of size 512 X 512 using LSB 2-bit
Method
Cover
Image
Message
MSE
PSNR
(db)
AFCPV
Percent
Change
Change (0 to
1) in %
Change (1To
0) in %
CV1
1
0.252
54.114
0.651
25.214
12.760
12.454
CV2
1
0.252
54.122
0.267
25.170
12.458
12.712
CV3
1
0.251
54.137
0.341
25.085
12.558
12.527
CV4
1
0.242
54.294
0.287
24.191
11.367
12.823
CV5
1
0.256
54.056
0.168
25.555
12.206
13.349
CV6
1
0.257
54.033
1.478
25.691
13.905
11.786
CV7
1
0.249
54.161
1.093
24.944
12.505
12.439
CV8
1
0.321
53.067
0.417
32.090
25.726
6.364
CV9
1
0.252
54.108
0.308
25.249
12.797
12.452
CV10
1
0.229
54.535
0.420
22.885
6.679
16.206
CV11
1
0.252
54.110
0.197
25.237
12.226
13.012
CV12
1
0.372
52.431
0.144
37.151
0.422
36.729
CV13
1
0.257
54.030
0.228
25.707
12.855
12.851
CV14
1
0.233
54.463
0.413
23.266
9.418
13.849
CV15
1
0.269
53.839
0.564
26.867
11.429
15.438
0.263
53.967
0.465
26.287
11.954
14.333
Average
Table No 3.4 Average values of MSE, PSNR, AFCPV, Total bytes changed , Changes
(0 to 1) and Changes (1 to 0) in percent for embedding 10 message images 1-10
in Cover images cvimg1 - cvimg15( 512 X 512) using LSB 2-bit Method
Message
MSE
PSNR
(db)
AFCPV
Percent
Change
% change
( 0 To 1)
% change
(1To 0)
1
2
3
4
5
6
7
8
9
10
0.263
0.260
0.254
0.242
0.258
0.266
0.260
0.258
0.261
0.248
53.967
53.996
54.086
54.314
54.031
53.927
54.004
54.018
53.994
54.196
0.465
0.475
0.493
0.512
0.473
0.452
0.467
0.488
0.472
0.512
26.287
26.033
25.401
24.160
25.791
26.624
25.996
25.850
26.051
24.756
11.954
12.026
11.842
11.864
11.972
11.954
12.052
11.987
12.010
11.833
14.333
14.007
13.559
12.296
13.819
14.671
13.944
13.863
14.041
12.923
Remark: It is observed that the maximum AFCPV is 0.512 and maximum Average
Percentage change is 26.624 with LSB2 method for Cover of size 512X512
Similarly Table 3.5 shows the values of MSE, PSNR, AFCPV,
Percentage of bytes changed, Changes (Zero to One) in percent and
Changes (One to Zero) in percent for embedding a message image
of an ATM Card (Message1) in Cover images 16 -30 of size 1024 X
1024 using LSB 2-bit Method. The last row shows their average
values for Cover images 16 – 30
53
Information Hiding in Image and Audio Files
2007-2010
Table No 3.5 Values of MSE, PSNR, AFCPV, bytes changed , Changes (0 to 1) and
Changes (1 to 0) in percent for embedding a message image of an ATM Card
(Message1) in Cover images 16 -30 of size 1024 X 1024 using LSB 2-bit Method
Cover
Image
Message
MSE
PSNR
(db)
AFCPV
Percent
Change
Change (0 to
1) in %
Change (1To
0) in %
CV16
1
0.065
60.026
0.066
6.464
3.218
3.246
CV17
1
0.064
60.038
0.043
6.446
2.467
3.979
CV18
1
0.062
60.182
0.097
6.236
3.190
3.046
CV19
1
0.064
60.101
0.036
6.353
3.198
3.155
CV20
1
0.062
60.192
0.066
6.221
3.031
3.190
CV21
1
0.065
59.998
0.276
6.505
3.496
3.009
CV22
1
0.093
58.452
0.036
9.288
0.000
9.288
CV23
1
0.064
60.069
0.070
6.400
2.684
3.716
CV24
1
0.088
58.710
0.046
8.751
8.189
0.562
CV25
1
0.063
60.162
0.076
6.264
3.089
3.175
CV26
1
0.062
60.190
0.036
6.224
3.145
3.080
CV27
1
0.068
59.832
0.055
6.759
3.540
3.220
CV28
1
0.060
60.351
0.044
5.998
2.571
3.428
CV29
1
0.090
58.584
0.035
9.010
0.000
9.010
CV30
1
0.063
60.124
0.035
6.320
2.827
3.493
Average
1
0.069
59.801
0.068
6.883
2.976
3.906
Table 3.6 shows the average values of MSE, PSNR, AFCPV,
Percentage of bytes changed, Changes (0 to 1) and (1 to 0) in
percent for Cover images 16 - 30 of size 1024 X 1024 using LSB 2bit Method with 10 different message images embedded in them.
Table No 3.6 Average values of MSE, PSNR, AFCPV, Total bytes changed , Changes
(0 to 1) and (1 to 0) in percent for 10 message images in Cover images 16 - 30 of
size 1024 X 1024 using LSB 2-bit Method
Message
MSE
PSNR
(db)
AFCPV
% change
% change
(0- 1)
% change
(1- 0)
1
0.069
59.801
0.068
6.883
2.976
3.906
2
0.067
59.891
0.068
6.714
2.939
3.775
3
0.066
59.976
0.071
6.555
2.896
3.658
4
0.060
60.387
0.072
5.984
2.775
3.208
5
0.067
59.889
0.068
6.706
2.968
3.738
6
0.071
59.693
0.067
7.092
3.053
4.039
7
0.068
59.867
0.068
6.750
2.963
3.787
8
0.066
59.985
0.069
6.556
2.886
3.670
9
0.068
59.858
0.068
6.770
2.973
3.797
10
0.062
60.183
0.072
6.238
2.837
3.401
Remark: It is observed that the maximum AFCPV is 0.072 and maximum Average
Percentage change is 7.092 with LSB2 method for Cover of size 1024 X 1024
54
Information Hiding in Image and Audio Files
2007-2010
Figure 3.10 and Figure 3.11 show the average MSE values, Figure
3.12 and Figure 3.13 show the average PSNR values, Figure 3.14
and Figure 3.15 show the average AFCPV values and Figure 3.16
and Figure 3.17 show the average changes Total bytes changed,
changes (0-1) and changes (1-0) in percent using LSB-2 algorithm
for Cover size 512 X 512 and 1024 X 1024 respectively.
MSE : LSB 2 Algorithm Cover 512 X 512
MSE : LSB 2 Algorithm Cover 1024X 1024
0.0709
0.0720
0.0688
0.0700
0.0671
0.0671 0.0675 0.0677
0.0680
0.0656
0.0655
0.0660
0.0624
0.0640
0.0620
0.0598
0.0600
0.0580
0.0560
0.0540
0.266
0.261
0.258 0.2600.258
0.270 0.263
0.260
0.265
0.260
0.254
0.255
0.250
0.242
0.245
0.240
0.235
0.230
0.225
0.248
MSEC
MSEC
Figure 3.10 Average MSE value for 15
Cover images of (512X512) using LSB-2
algorithm
for
embedding
10
different
images of size 128X128
Figure 3.11 Average MSE for 15 Cover
images
3.12
Average
for
using
embedding
10
LSB-2
different
PSNRC : LSB 2 Algorithm Cover 1024X1024
60.60
60.39
60.40
60.18
60.20
59.98
59.98
59.89 59.87 59.86
60.00 59.8059.89
59.69
59.80
59.60
59.40
59.20
AVG PSNR =54.05
PSNR
for
message images of size 128 X 128
54.40
54.31
54.30
54.20
54.20
54.09
54.03 54.0054.0253.99
54.10
53.9754.00
53.93
54.00
53.90
53.80
53.70
Figure
(1024X1024)
algorithm
PSNRC : LSB 2 Algorithm Cover 512 X 512
PSNRC
AVG MSE = 0.066
Cover
PSNRC
Figure
3.13
AVG PSNR =59.95
Average
PSNR
for
Cover
images 1-15 of size 512 X 512 using LSB-
images 16-30 of size 1024 X 1024 using
2 algorithm for embedding 10 different
LSB-2
message images (128 X 128)
different message images (128 X 128)
55
algorithm
for
embedding
10
Information Hiding in Image and Audio Files
AFCPV : LSB 2 Algorithm Cover 512 X 512
0.520
0.510
0.493
0.500
0.490
0.475
0.480 0.465
0.470
0.460
0.450
0.440
0.430
0.420
AFCPV : LSB 2 Algorithm Cover 1024X 1024
0.072
0.073
0.072
0.072
0.071
0.071
0.070
0.069
0.068
0.068
0.068 0.068
0.069 0.068
0.067
0.068
0.067
0.066
0.065
0.064
0.512
0.512
0.488
0.472
0.467
0.452
0.473
AFCPV
2007-2010
AVG AFCPV=0.481
AFCPV
AVG AFCPV=0.069
Figure 3.14 Average AFCPV for Cover
Figure 3.15 Average AFCPV for Cover
images 1-15 of size 512 X 512 using LSB-
images of size 1024X1024 using LSB-2
2 algorithm for 10 messages (128 X 128)
algorithm for 10 messages (128 X 128)
% CHANGE : LSB 2 Algorithm Cover 512 X
512 26.62
27.00 26.29
26.05
26.03
26.50
25.79 26.0025.85
26.00
25.40
25.50
24.76
25.00
24.16
24.50
24.00
23.50
23.00
22.50
Total % Change
Figure
3.16
Average
% CHANGE : LSB 2 Algorithm Cover 1024X
1024 7.09
7.20
6.88
7.00
6.77
6.75
6.71
6.71
6.80
6.56
6.55
6.60
6.24
6.40
6.20
5.98
6.00
5.80
5.60
5.40
Total %
Change
AVG % CHANGE=25.69
values
for
total
Figure
3.17
Average
values
for
total
change in percent. for Cover images 1-15
change in percent. for Cover images 16-
of size 512 X 512 using LSB-2 algorithm
30
for 10 message images (128 X 128)
algorithm for 10 messages (128 X 128)
of
size
1024X1024
using
LSB-2
Table 3.7 shows the average values of MSE, PSNR, AFCPV,
Percentage of bytes changed, Changes (0 to 1) in percent and
Changes (1 to 0) in percent for Cover images 1 - 15 of size 512 X
512 using LSB 3-bit Method with 10 different message images
embedded in them.
56
Information Hiding in Image and Audio Files
2007-2010
Table No 3.7 Average values of MSE, PSNR, AFCPV, Percentage of bytes changed
and AFCPV for 10 message images in Cover images 1 -15 of size 512 X 512 using
LSB 3-bit Method
Message
Average
MSE
Average
PSNR (db)
Average
AFCPV
Average%
Change
Average
%
change (0 - 1)
Average%
change (1- 0)
1
0.2512
54.191
0.489
25.12
13.02
12.10
2
0.2513
54.161
0.491
25.13
12.73
12.40
3
0.2485
54.183
0.502
24.85
12.20
12.65
4
0.2496
54.171
0.505
24.96
11.36
13.60
5
0.2513
54.151
0.492
25.13
12.57
12.56
6
0.2513
54.239
0.484
25.13
13.19
11.94
7
0.2520
54.151
0.486
25.20
12.77
12.43
8
0.2500
54.168
0.498
25.00
12.59
12.42
9
0.2514
54.162
0.491
25.14
12.79
12.36
10
0.2478
54.192
0.509
24.78
11.72
13.06
Remark: It is observed that the maximum AFCPV is 0.509 and maximum Average
Percentage change is 25.20 with LSB2 method for Cover of size 512 X 512
Table 3.8 shows the average values of MSE, PSNR, AFCPV,
Percentage of bytes changed, Changes (0 to 1) in percent and
Changes (1 to 0) in percent for Cover images 16 - 30 of size 1024 X
1024 using LSB 3-bit Method with 10 different message images
embedded in them.
Table No 3.8 Average values of MSE, PSNR, AFCPV, Percentage of bytes changed
and AFCPV for 10 message images in Cover images 16 - 30 of size 1024 X 1024
using LSB 3-bit Method
Message
Average
MSE
Average
PSNR(db)
Average
AFCPV
Average
%
change
Average
% change
(0- 1)
Average
% change
(1- 0)
1
0.0604
60.43
0.0646
6.04
3.06
2.98
2
0.0607
60.36
0.0659
6.07
2.99
3.08
3
0.0618
60.23
0.0691
6.18
2.91
3.27
4
0.0636
60.12
0.0730
6.36
2.70
3.66
5
0.0611
60.31
0.0661
6.11
2.96
3.16
6
0.0597
60.57
0.0631
5.97
3.10
2.87
7
0.0608
60.35
0.0655
6.08
2.98
3.10
8
0.0614
60.28
0.0676
6.14
2.97
3.17
9
0.0607
60.36
0.0655
6.07
3.02
3.05
10
0.0629
60.15
0.0716
6.29
2.82
3.47
Remark: It is observed that the maximum AFCPV is 0.073 and maximum Average
Percentage change is 6.36 with LSB3 method for Cover of size 1024 X 1024
Figure 3.18 and Figure 3.19 show the average MSE values for Cover
size 512 X 512 and 1024 X 1024 respectively. Figure 3.20 and
57
Information Hiding in Image and Audio Files
2007-2010
Figure 3.21 show the average PSNR values, Figure 3.22 and Figure
3.23 show the average AFCPV values and Figure 3.24 and Figure
3.25 show the average changes i.e. Total bytes changed, in percent
using changes in percent using LSB-3 algorithm for Cover size 512
X 512 and 1024 X 1024 respectively.
MSE : LSB 3 Algorithm Cover 512 X 512
MSE : LSB 3 Algorithm Cover 1024X 1024
0.071
0.072
0.069
0.070
0.067
0.067 0.068 0.068
0.068
0.066
0.066
0.066
0.062
0.064
0.062
0.060
0.060
0.058
0.056
0.054
0.266
0.261
0.258 0.2600.258
0.270 0.263
0.260
0.265
0.260
0.254
0.255
0.250
0.242
0.245
0.240
0.235
0.230
0.225
MSEC
0.248
AVG MSE = 0.257
MSEC
AVG MSE = 0.066
Figure 3.18 Average MSE value for 15
Figure 3.19 Average MSE for 15 Cover
Cover images of (512X512) using
images
algorithm
for
embedding
10
LSB-3
different
images of size 128X128
for
using
embedding
10
LSB-3
different
message images of size 128 X 128
PSNRC : LSB 3 Algorithm Cover 512 X 512
PSNRC : LSB 3 Algorithm Cover 1024X1024
54.40
54.31
54.30
54.20
54.20
54.09
54.03 54.0054.0253.99
54.10
53.9754.00
53.93
54.00
53.90
53.80
53.70
PSNRC
(1024X1024)
algorithm
60.60
60.39
60.40
60.18
60.20
59.98
59.98
59.89 59.87 59.86
60.00 59.8059.89
59.69
59.80
59.60
59.40
59.20
AVG PSNR =54.05
PSNRC
Figure 3.20 Average PSNR(db) for Cover
Figure
images 1-15 of size 512 X 512 using LSB-
images 16-30 of size 1024 X 1024 using
3 algorithm for embedding 10 different
LSB-3
message images (128 X 128)
different message images (128 X 128)
58
3.21
AVG PSNRC =59.95
Average
algorithm
for
PSNR
for
Cover
embedding
10
Information Hiding in Image and Audio Files
AFCPV : LSB 3 Algorithm Cover 512 X 512
AFCPV : LSB 3 Algorithm Cover 1024 X1024
0.072
0.073
0.072
0.072
0.071
0.071
0.070
0.069
0.068
0.068
0.068 0.068
0.069 0.068
0.067
0.068
0.067
0.066
0.065
0.064
0.512
0.512
0.520
0.510
0.493
0.488
0.500
0.490
0.475
0.473
0.472
0.480 0.465
0.467
0.470
0.452
0.460
0.450
0.440
0.430
0.420
AFCPV
2007-2010
AVG AFCPV=0.481
AFCPV
AVG AFCPV=0.069
Figure 3.22 Average AFCPV for Cover
Figure 3.23 Average AFCPV for Cover
images 1-15 of size 512 X 512 using LSB-
images 16-30 of size 1024X1024 using
3 algorithm for embedding 10 different
LSB-3 algorithm for embedding 10
message images (128 X 128)
different message images (128 X 128)
% CHANGE : LSB 3 Algorithm Cover 512 X
512 26.62
27.00 26.29
26.05
26.03
26.50
25.79 26.0025.85
26.00
25.40
25.50
24.76
25.00
24.16
24.50
24.00
23.50
23.00
22.50
Total % Change
% CHANGE : LSB 3 Algorithm Cover 1024X
1024 7.09
7.20
6.88
7.00
6.77
6.75
6.71
6.71
6.80
6.56
6.55
6.60
6.24
6.40
6.20
5.98
6.00
5.80
5.60
5.40
AVG % CHANGE=25.69
Figure 3.24 Average values for total
change, in percent. for 15 Cover images
(512 X 512) using LSB-3 algorithm for
embedding 10 images (128 X 128)
Total % Change
AVG % CHANGE=6.62
Figure 3.25 Average values for total
change, in percent. for 15 Cover images
(1024X1024) using LSB-3 algorithm for
embedding 10 images (128 X 128)
Table 3.9 shows the average values of MSE, PSNR, AFCPV, and
Percentage of bytes changed, for Cover images 1 - 15 of size 512 X
512 using LSB Parity Method with 10 different message images
embedded in them.
59
Information Hiding in Image and Audio Files
2007-2010
Table No 3.9 Average values of MSE, PSNR, AFCPV, Percentage of bytes changed
and AFCPV for 10 message images in Cover images 1 -15 of size 512 X 512 using
LSB Parity Method
Message
1
2
3
4
5
6
7
8
9
10
Average
MSE
Average
PSNR
(db)
Average
AFCPV
Average
%
change
Average
%
change
(0- 1)
Average
%
change
(1- 0)
0.263
53.97
0.464
26.29
12.42
13.87
0.260
54.00
0.472
26.00
12.33
13.66
0.254
54.09
0.495
25.41
11.96
13.45
0.242
54.30
0.514
24.22
11.61
12.61
0.259
54.02
0.470
25.85
12.22
13.63
0.266
53.92
0.452
26.64
12.47
14.17
0.260
54.00
0.465
26.01
12.29
13.71
0.258
54.02
0.487
25.83
12.29
13.54
0.260
54.00
0.469
26.03
12.32
13.71
0.248
54.19
0.515
24.82
11.81
13.00
Remark: It is observed that the maximum AFCPV is 0.514 and maximum Average
Percentage change is 26.64 with LSB Parity method for Cover of size 512 X 512
Table 3.10 shows the average values of MSE, PSNR, AFCPV,
Percentage of bytes changed, Changes (0 to 1) in percent and
Changes (1 to 0) in percent for Cover images 16 - 30 of size 1024 X
1024 using LSB Parity Method with 10 different message images
embedded in them.
Table No 3.10 Average values of MSE, PSNR, AFCPV, Percentage of bytes changed
and AFCPV for 10 messages image in Cover images 16 - 30 of size 1024 X 1024
using LSB Parity Method
Message
Average
MSE
Average
PSNR
(db)
Average
AFCPV
Average
%
change
Average
%
change
(0- 1)
Average
%
change
(1- 0)
1
0.069
59.81
0.0679
6.86
3.01
3.86
2
0.067
59.92
0.0681
6.68
2.95
3.73
3
0.065
60.03
0.0700
6.48
2.85
3.62
4
0.060
60.40
0.0716
5.96
2.74
3.22
5
0.066
59.96
0.0679
6.60
2.91
3.69
6
0.070
59.78
0.0666
6.97
3.03
3.94
7
0.067
59.91
0.0679
6.69
2.97
3.73
8
0.066
59.96
0.0692
6.59
2.93
3.66
9
0.067
59.89
0.0680
6.72
2.96
3.76
10
0.062
60.21
0.0712
6.19
2.78
3.42
Remark: It is observed that the maximum AFCPV is 0.0716 and maximum
Average % change is 6.97 with LSB Parity method for Cover of size 1024 X 1024
Figure 3.26 and Figure 3.27 show the average MSE values for Cover
size 512 X 512 and 1024 X 1024 respectively.
60
Information Hiding in Image and Audio Files
2007-2010
Figure 3.28 and Figure 3.29 show the average PSNR values, Figure
3.30 and Figure 3.31 show the average AFCPV values and Figure
3.32 and Figure 3.33 show the average changes i.e. Total bytes
changed, in percent using changes in percent using LSB-3 algorithm
for Cover size 512 X 512 and 1024 X 1024 respectively.
0.270
0.265
0.260
0.255
0.250
0.245
0.240
0.235
0.230
0.225
MSE : LSB Parity Algorithm
Cover 1024X 1024
0.071
0.072
0.069
0.070
0.067
0.067 0.068 0.068
0.068
0.066
0.066
0.066
0.062
0.064
0.062
0.060
0.060
0.058
0.056
0.054
MSE : LSB Parity Algorithm
Cover 512 X 512
0.266
0.263
0.261
0.260
0.258 0.2600.258
0.254
0.248
0.242
MSEC
MSEC
AVG MSE = 0.066
Figure 3.26 Average MSE value for 15
Figure 3.27 Average MSE for 15 Cover
Cover images of (512X512) using
images
Parity
algorithm
for
LSB-
embedding
10
different images of size 128X128
algorithm
3.28
PSNR
for
10
different
60.600
60.387
60.400
60.183
60.200
59.985
59.976
59.891
59.889 59.867 59.858
60.000 59.801
59.693
59.800
59.600
59.400
59.200
AVG PSNRC =54.05
Average
embedding
LSB-Parity
PSNRC : LSB Parity Algorithm
Cover 1024X1024
54.400
54.300
54.196
54.200
54.086
54.031 54.004
54.018
54.100
53.996
53.994
53.967
53.927
54.000
53.900
53.800
53.700
Figure
for
using
message images of size 128 X 128
PSNRC : LSB Parity Algorithm
Cover 512 X 512
54.314
PSNRC
(1024X1024)
PSNRC
Cover
Figure
3.29
Average
AVG PSNRC =59.953
PSNR
for
Cover
images 1-15 of size 512 X 512 using LSB-
images 16-30 of size 1024 X 1024 using
Parity
LSB-Parity algorithm for embedding 10
algorithm
for
embedding
different message images (128 X 128)
10
different message images (128 X 128)
61
Information Hiding in Image and Audio Files
AFCPV : LSB Parity Algorithm
Cover
512 X 512
0.512
0.520
0.510
0.493
0.500
0.490
0.475
0.480 0.465
0.470
0.460
0.450
0.440
0.430
0.420
AFCPV : LSB Parity Algorithm
Cover 1024 X 1024
0.072
0.071
0.512
0.073
0.072
0.071
0.070
0.068
0.069 0.068
0.068
0.067
0.066
0.065
0.064
0.488
0.472
0.467
0.452
0.473
AFCPV
2007-2010
AVG AFCPV=0.481
0.072
0.069
0.068 0.068
0.067
0.068
AFCPV
AVG AFCPV=0.069
Figure 3.30 Average AFCPV for Cover
Figure 3.31 Average AFCPV for Cover
images 1-15 of size 512 X 512 using LSB-
images 16-30 of size 1024X1024 using
Parity
LSB-Parity algorithm for embedding 10
algorithm
for
embedding
10
different message images (128 X 128)
27.000
26.500
26.000
25.500
25.000
24.500
24.000
23.500
23.000
22.500
% CHANGE : LSB Parity Algorithm Cover
1024X 1024
7.092
7.200
6.883
7.000
6.714
6.706 6.750 6.770
6.800
6.556
6.555
6.600
6.238
6.400
6.200
5.984
6.000
5.800
5.600
5.400
% CHANGE : LSB Parity Algorithm
Cover 512 X 26.624
512
26.287
26.051
26.033
25.850
25.791 25.996
25.401
24.756
24.160
Total % Change
Figure
different message images (128 X 128)
3.32
Average
AVG % CHANGE=25.695
values
for
total
Total % Change
Figure
3.33
Average
AVG % CHANGE=6.625
values
for
total
change in percent. for 15 Cover images
change in percent. for 15 Cover images
(512 X 512) using LSB-Parity algorithm
(1024X1024) using LSB-Parity algorithm
for embedding 10 images (128 X 128)
for embedding 10 images (128 X 128)
Table 3.11, Table 3.13 and Table 3.15 shows the average values of
MSE, PSNR, AFCPV, Percentage of bytes changed, Changes (0 to 1)
and Changes (1 to 0) in percent for Cover images 1 - 15 of size 512
X 512 using LSB-2, LSB-3, LSB Parity Method respectively with 4
different Microsoft Word documents embedded in them.Table 3.12,
Table 3.14 and Table 3.16 shows the average values of MSE, PSNR,
AFCPV, Percentage of bytes changed, Changes (0 to 1) and
Changes (1 to 0) in percent for Cover images 16 - 30 of size 1024 X
62
Information Hiding in Image and Audio Files
2007-2010
1024 using LSB-2, LSB-3, LSB Parity Method respectively with 4
different Microsoft Word documents embedded in them.
Table No 3.11 Average values of MSE, PSNR, AFCPV, Percentage of bytes changed
and AFCPV for 4 Microsoft Word messages in Cover images 1 -15 of size 512 X
512 using LSB-2 Method
Message
MSE
AFCPV
0.07
0.06
0.12
PSNR
(db)
59.64
60.56
57.44
1
2
3
4
0.15
0.12
0.26
%
change
7.07
5.73
11.74
%
change
(0- 1)
3.49
2.86
5.70
%
change
(1- 0)
3.58
2.88
6.05
0.10
58.32
0.21
9.58
4.70
4.88
Remark: It is observed that the maximum AFCPV is 0.26 and maximum Average
% change is 11.74 with LSB2 method for Cover size 512X512 with Text message
Table No 3.12 Average values of MSE, PSNR, AFCPV, Percentage of bytes changed
and AFCPV for 4 Microsoft Word messages in Cover images 1 -15 of size 1024 X
1024 using LSB-2 Method
Message
MSE
PSNR
(db)
AFCPV
%
change
%
change
(0- 1)
%
change
(1- 0)
1
2
3
4
0.017
0.014
0.029
0.024
65.73
66.62
63.50
64.39
0.02
0.02
0.03
0.03
1.74
1.42
2.91
2.37
0.80
0.65
1.34
1.09
0.95
0.77
1.57
1.28
Remark: It is observed that the maximum value of AFCPV is 0.03 and Average %
change is 2.91 with LSB2 method for Cover size 1024X1024 with Text message
Table No 3.13 Average values of MSE, PSNR, AFCPV, Percentage of bytes changed
and AFCPV for 4 Microsoft Word messages in Cover images 1 -15 of size 512 X
512 using LSB-3 Method
Message
MSE
PSNR
(db)
AFCPV
%
change
%
change
(0- 1)
%
change
(1- 0)
1
0.07
59.56
0.150
7.21
3.40
3.81
2
0.06
60.45
0.117
5.88
2.76
3.11
3
0.12
57.37
0.256
11.92
5.59
6.33
4
0.10
58.24
0.211
9.77
4.58
5.19
Remark: It is observed that the maximum AFCPV is 0.256 and maximum Average
% change is 11.92 with LSB3 method for Cover size 512X512 with Text message
63
Information Hiding in Image and Audio Files
2007-2010
Table No 3.14 Average values of MSE, PSNR, AFCPV, Percentage of bytes changed
and AFCPV for 4 Microsoft Word messages in Cover images 16 -30 of size 1024 X
1024 using LSB-3 Method
Message
MSE
PSNR
(db)
AFCPV
%
change
% change
(0- 1)
% change
(1- 0)
1
0.0184
65.50
0.020
1.84
0.79
1.05
2
0.0151
66.37
0.016
1.51
0.64
0.87
3
0.0301
63.35
0.033
3.01
1.33
1.68
4
0.0248
64.19
0.027
2.48
1.08
1.40
Remark: It is observed that the maximum value of AFCPV is 0.033 and Average
% change is 3.01 with LSB2 method for Cover size 1024X1024 with Text message
Table No 3.15 Average values of MSE, PSNR, AFCPV, Percentage of bytes changed
and AFCPV for 4 Microsoft Word messages in Cover images 1 -15 of size 512 X
512 using LSB-Parity Method
Message
MSE
PSNR
(db)
AFCPV
%
change
%
change
(0- 1)
%
change
(1- 0)
1
0.07
59.63
0.15
7.09
3.46
3.63
2
0.06
60.53
0.12
5.77
2.82
2.95
3
0.12
57.43
0.26
11.75
5.65
6.10
4
0.10
58.31
0.21
9.61
4.65
4.96
Remark: It is observed that the maximum AFCPV is 0.26 and Average % change
is 11.75 with LSB Parity method for Cover size 512X512 with Text message
Table No 3.16 Average values of MSE, PSNR, AFCPV, Percentage of bytes changed
and AFCPV for 4 Microsoft Word messages in Cover images 16 -30 of size 1024 X
1024 using LSB-Parity Method
Message
MSE
PSNR
(db)
AFCPV
%
change
%
change
(0- 1)
%
change
(1- 0)
1
0.0176
65.68
0.020
1.76
0.81
0.96
2
0.0143
66.58
0.016
1.43
0.65
0.78
3
0.0293
63.47
0.032
2.93
1.35
1.58
4
0.0239
64.36
0.027
2.39
1.10
1.29
Remark: It is observed that the maximum value of AFCPV is 0.032 and Average
% change is 2.93 with LSB2 method for Cover size 1024X1024 with Text message
Figure 3.34 and Figure 3.35 show the average MSE values. Figure
3.36 and Figure 3.37 show the average PSNR values, Figure 3.38
and Figure 3.39 show the average AFCPV values and Figure 3.40
and Figure 3.41 show the average changes i.e. Total bytes changed,
in percent for 4 Microsoft Word messages in Cover size 512 X 512
and 1024 X 1024 respectively using LSB-2 algorithm.
64
Information Hiding in Image and Audio Files
MSE : LSB 2 Algorithm Cover 512 X 512
0.140
0.120
0.100
0.080
0.060
0.040
0.020
0.000
MSE : LSB 2 Algorithm Cover 1024x1024
0.035
0.030
0.025
0.020
0.015
0.010
0.005
0.000
0.117
0.071
0.057
0.024
MSG1
MSG2
MSEC
MSG3
2007-2010
MSG4
0.029
0.024
0.017
MSG1
AVG MSE=0.067
0.014
MSG2
MSEC
MSG3
MSG4
AVG MSE=0.021
Figure 3.34 Average MSE value for 15 Cover
images of (512X512) using
LSB-2
algorithm
for
embedding
4
different
Microsoft Word documents
Figure 3.35 Average MSE value for 15 Cover
images of (1024X1024) using
LSB-2
algorithm
for
embedding
4
different
Microsoft Word documents
PSNR : LSB 2 Algorithm Cover 512 X 512
PSNR : LSB 2 Algorithm Cover 1024x1024
66.000
64.000
62.000
60.000
58.000
56.000
54.000
52.000
64.330
59.644
67.000
66.500
66.000
65.500
65.000
64.500
64.000
63.500
63.000
62.500
62.000
61.500
60.558
57.435
MSG1
MSG2
PSNRC
MSG3
MSG4
66.624
65.726
64.394
63.503
MSG1
AVG PSNR=60.492
MSG2
PSNRC
MSG3
MSG4
AVG PSNR=65.062
Figure 3.36 Average PSNR value for 15
Cover images of (512X512) using LSB-2
algorithm
for
embedding
4
different
Microsoft Word documents
Figure 3.37
Average PSNR value for 15
Cover images of (1024X1024) using LSB-2
algorithm
for
embedding
4
different
Microsoft Word documents
AFCPV : LSB 2 Algorithm Cover 512 X 512
AFCPV : LSB 2 Algorithm Cover 1024x1024
0.300
0.035
0.030
0.025
0.020
0.015
0.010
0.005
0.000
0.257
0.250
0.200
0.150
0.118
0.150
0.100
0.020
0.050
0.000
MSG1
AFCPV
MSG2
MSG3
MSG4
0.027
0.020
0.016
MSG1
AVG AFCPV=0.136
Figure 3.38 Average AFCPV value for 15
Cover images of (512X512) using LSB-2
algorithm
for
embedding
4
different
Microsoft Word documents
0.032
AFCPV
MSG2
MSG3
MSG4
AVG AFCPV=0.024
Figure 3.39 Average AFCPV value for 15
Cover images of (1024X1024) using LSB-2
algorithm
for
embedding
4
different
Microsoft Word documents
65
Information Hiding in Image and Audio Files
% CHANGE : LSB 2 Algorithm Cover 512 X
512
14.00
11.74
12.00
10.00
7.07
8.00
5.73
6.00
2.40
4.00
2.00
0.00
MSG1
MSG2
Total % Change
MSG3
2007-2010
% CHANGE : LSB 2 Algorithm Cover
1024x1024
3.500
2.906
3.000
2.369
2.500
1.744
2.000
1.421
1.500
1.000
0.500
0.000
MSG4
MSG1
AVG % CHANGE=6.74
MSG2
Total % Change
Figure 3.40 Average values for total change
in percent. for 15 Cover images (512X512)
using
LSB-2
algorithm
for4
different
Microsoft Word documents
MSG3
MSG4
AVG % CHANGE=2.110
Figure 3.41 Average values for total change
in
percent.
for
15
Cover
images
(1024X1024) using LSB-2 algorithm for 4
different Microsoft Word documents
Figure 3.42 and Figure 3.43 show the average MSE values. Figure
3.44 and Figure 3.35 show the average PSNR values, Figure 3.46
and Figure 3.47 show the average AFCPV values and Figure 3.48
and Figure 3.49 show the average changes i.e. Total bytes changed,
in percent for 4 Microsoft Word messages in Cover size 512 X 512
and 1024 X 1024 respectively using LSB-3 algorithm.
MSE : LSB 3 Algorithm Cover 512 X 512
0.140
0.120
0.100
0.080
0.060
0.040
0.020
0.000
MSE : LSB 3 Algorithm Cover 1024x1024
0.035
0.030
0.025
0.020
0.015
0.010
0.005
0.000
0.119
0.098
0.072
MSG1
MSEC
0.059
MSG2
MSG3
MSG4
0.030
0.025
0.018
MSG1
AVG MSE=0.087
MSEC
Figure 3.42 Average MSE value for 15
Cover images of (512X512) using LSB-3
algorithm for embedding 4 different
Microsoft Word documents
0.015
MSG2
MSG3
MSG4
AVG MSE0.022
Figure 3.43 Average MSE value for 15
Cover images of (1024X1024) using LSB3 algorithm for embedding 4 different
Microsoft Word documents
66
Information Hiding in Image and Audio Files
PSNR : LSB 3 Algorithm Cover 512 X 512
61.000
60.500
60.000
59.500
59.000
58.500
58.000
57.500
57.000
56.500
56.000
55.500
PSNR : LSB 3 Algorithm Cover 1024x1024
60.451
67.000
66.500
66.000
65.500
65.000
64.500
64.000
63.500
63.000
62.500
62.000
61.500
59.557
58.238
57.371
MSG1
MSG2
PSNRC
MSG3
2007-2010
MSG4
66.370
65.495
64.192
63.351
MSG1
AVG PSNRC=58.904
MSG2
PSNRC
MSG3
MSG4
AVG PSNR=65.852
Figure 3.44 Average PSNR value for 15
Cover images of (512X512) using LSB-3
algorithm for embedding 4 different
Microsoft Word documents
Figure 3.45 Average PSNR value for 15
Cover images of (1024X1024) using LSB3 algorithm for embedding 4 different
Microsoft Word documents
AFCPV : LSB 3 Algorithm Cover 512 X 512
AFCPV : LSB 3 Algorithm Cover 1024x1024
0.300
0.250
0.200
0.035
0.030
0.025
0.020
0.015
0.010
0.005
0.000
0.256
0.211
0.150
0.117
0.150
0.100
0.050
0.000
MSG1
MSG2
AFCPV
MSG3
MSG4
AVG AFCPV=0.183
Total % Change
MSG3
0.020
0.016
MSG2
AFCPV
MSG3
MSG4
AVG AFCPV=0.024
Figure 3.47 Average AFCPV value for 15
Cover images of (1024X1024) using LSB3 algorithm for embedding 4 different
Microsoft Word documents
% CHANGE : LSB 3 Algorithm Cover 512 X
512
14.000
11.920
12.000
9.769
10.000
7.213
8.000
5.878
6.000
4.000
2.000
0.000
MSG2
0.027
MSG1
Figure 3.46 Average AFCPV value for 15
Cover images of (512X512) using LSB-3
algorithm for embedding 4 different
Microsoft Word documents
MSG1
0.033
% CHANGE : LSB 3 Algorithm Cover
1024x1024
3.500
3.010
3.000
2.482
2.500
1.839
2.000
1.506
1.500
1.000
0.500
0.000
MSG4
MSG1
AVG % CHANGE=8.695
Total % Change
Figure 3.48 Average values for total
change in percent. for 15 Cover images
(512X512) using LSB-3 algorithm for
embedding 4 different Microsoft Word
documents
MSG2
MSG3
MSG4
AVG % CHANGE=2.209
Figure 3.49 Average values for total
change in percent. for 15 Cover images
(1024X1024) using LSB-3 algorithm for 4
different Microsoft Word documents
67
Information Hiding in Image and Audio Files
2007-2010
Figure 3.50 and Figure 3.51 show the average MSE values. Figure
3.52 and Figure 3.53 show the average PSNR values, Figure 3.54
and Figure 3.55 show the average AFCPV values and Figure 3.56
and Figure 3.57 show the average changes i.e. Total bytes changed,
in percent for 4 Microsoft Word messages in Cover size 512 X 512
and 1024 X 1024 respectively using LSB-Parity algorithm.
MSE EvPR Algorithm Cover 512 X 512
0.140
0.120
0.100
0.080
0.060
0.040
0.020
0.000
MSE : EvPR Algorithm Cover 1024x1024
0.035
0.030
0.025
0.020
0.015
0.010
0.005
0.000
0.12
0.10
0.07
MSG1
0.06
MSG2
MSEC
MSG3
MSG4
0.029
0.024
0.018
MSG1
AVG MSE=0.086
0.014
MSG2
MSEC
MSG3
MSG4
AVG MSE=0.021
Figure 3.50 Average MSE value for 15 Cover
images of (512X512) using
LSB-Parity
algorithm
for
embedding
4
different
Microsoft Word documents
Figure 3.51 Average MSE value for 15 Cover
images of (1024X1024) using LSB-Parity
algorithm
for
embedding
4
different
Microsoft Word documents
PSNR EvPR Algorithm Cover 512 X 512
PSNR EvPR Algorithm Cover 1024x1024
61.000
60.500
60.000
59.500
59.000
58.500
58.000
57.500
57.000
56.500
56.000
55.500
60.529
67.000
66.500
66.000
65.500
65.000
64.500
64.000
63.500
63.000
62.500
62.000
61.500
59.631
58.312
57.433
MSG1
PSNRC
MSG2
MSG3
MSG4
66.585
65.685
64.364
63.475
MSG1
AVG PSNR=58.976
PSNRC
Figure 3.52 Average PSNR value for 15
Cover images of (512X512) using
LSBParity algorithm for embedding 4 different
Microsoft Word documents
MSG2
MSG3
MSG4
AVG PSNRC=65.027
Figure 3.53
Average PSNR value for 15
Cover images of (1024X1024) using LSBParity algorithm for embedding 4 different
Microsoft Word documents
68
Information Hiding in Image and Audio Files
AFCPV : EvPR Algorithm Cover 512 X 512
0.300
0.200
AFCPV : EvPR Algorithm Cover 1024x1024
0.035
0.030
0.025
0.020
0.015
0.010
0.005
0.000
0.258
0.250
0.213
0.152
0.119
0.150
0.100
0.050
0.000
MSG1
MSG2
AFCPV
MSG3
MSG4
AVG AFCPV=0.185
Total % Change
MSG3
0.027
0.020
0.016
MSG2
AFCPV
3.500
3.000
2.500
2.000
1.500
1.000
0.500
0.000
MSG4
MSG4
AVG AFCPV=0.024
% CHANGE EvPR Algorithm Cover
1024x1024
2.925
2.387
1.762
MSG1
AVG % CHANGE=8.556
1.435
MSG2
Total % Change
Figure 3.56 Average values for total change,
change (0-1), change (1-0) all in percent.
for 15 Cover images (512X512) using LSBParity algorithm for4 different Microsoft
Word documents
MSG3
Figure 3.55 Average AFCPV value for 15
Cover images of (1024X1024) using LSBParity algorithm for embedding 4 different
Microsoft Word documents
% CHANGE: EvPR Algorithm Cover 512 X
512
14.000
11.751
12.000
9.605
10.000
7.092
8.000
5.775
6.000
4.000
2.000
0.000
MSG2
0.032
MSG1
Figure 3.54 Average AFCPV value for 15
Cover images of (512X512) using
LSBParity algorithm for embedding 4 different
Microsoft Word documents
MSG1
2007-2010
MSG3
MSG4
AVG % CHANGE=2.127
Figure 3.57 Average values for total change,
change (0-1), change (1-0) all in percent.
for 15 Cover images (1024X1024) using
LSB-Parity algorithm for4 different Microsoft
Word documents
Remark : It is observed that in case of Word documents higher MSE and theryby
lower PSNR is obtained when larger size messages are embedded and viceversa.
The pattern for MSE is same in case of all the three algorithms.
3.4 Discussion
Least Significant bit is one of the simplest techniques. It replaces
the LSB of every pixel directly with the message bit. Such a
69
Information Hiding in Image and Audio Files
2007-2010
technique can result to easy retrieval of the secret message. In this
chapter, three variations of LSB technique are given. In the first
variation of LSB, called as LSB 2-bit technique, the LSB of every
pixel is adjusted in such a way that XOR operation of LSB and next
to LSB is same as the secret message bit. Similarly the other two
variations are implemented. All these three different variations of
LSB technique are quite robust against easy retrieval of message as
LSB is not directly replaced with the secret message bit.
Experimental results show that LSB 2-bit technique, LSB 3-bit
technique and LSB Parity show lesser values of MSE, RMSE,
percentage of bytes changed and AFCPV for embedding text
message as secret message as compared to message image as
secret message as the total number of bytes for text message are
lesser than the total number of bytes of message image which
means that more amount of text message can be embedded.
70