1. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN
INTERNATIONAL JOURNAL OF ELECTRONICS AND
0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 1, January- February (2013), © IAEME
COMMUNICATION ENGINEERING & TECHNOLOGY (IJECET)
ISSN 0976 – 6464(Print)
ISSN 0976 – 6472(Online)
Volume 4, Issue 1, January- February (2013), pp. 230-235
IJECET
© IAEME: www.iaeme.com/ijecet.asp
Journal Impact Factor (2012): 3.5930 (Calculated by GISI) ©IAEME
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CONCEALOGRAM: DIGITAL IMAGE IN IMAGE USING LSB
INSERTION METHOD
Reena M Patel1, D J Shah2
1
EC department, LDRP Institute of Technology & Research, Near ITI, Sector 15,
Gandhinagar, Gujarat, India,
2
Principal, L C institute of technology, Bhandu 384124, Gujarat, India,
ABSTRACT
In this paper, the authors propose a new algorithm for an image hiding
steganographic method or concealing digital image in a cover image is introduced, and
implemented. The proposed algorithm uses binary codes and pixels inside an image. For
proposed paper author used spatial domain approach. The algorithm tested to see the
viability of the proposed algorithm. Here using different algorithm, same sizes of data are
stored inside the images and the PSNR (Peak signal-to-noise ratio) is also captured for
each of the images tested. Various parameters like robustness against attack, data hiding
capacity and quality of stego image are also considered. Hence this new steganography
algorithm is very efficient to hide the digital image inside the image.
Keywords: cover image, image processing, LSB insertion, Steganography, stegoimage
1. INTRODUCTION
Steganography is the science of hiding information. The goal of steganography is
to hide the information and be undetectable to human eyes. Steganography focuses on the
means of communication and the development of a covert channel. Steganography
focuses entirely on keeping the adversary completely unaware of the communication.
There are several information hiding techniques, they could be classified according to the
media where the information are hidden. First, Hiding in Text, methods such as line-shift
coding, word shift coding, and feature coding are the commonly used methods to hide
data in text. When using a text data as a host media, the embedded data are usually
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2. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN
0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 1, January- February (2013), © IAEME
codeword that are hidden within the text by altering their different textual features [1].
Second, data hiding in image, the least significant bit insertion method is a common
simple approach for embedding information in image file. When applying LSB insertion
method on each byte of a 24-bit image, three bits can be encoded into each pixel (because
each pixel is represented by three bytes). Any changes in the pixel bits will be
indiscernible to the human eye. When using LSB techniques on 8-bit color images (i.e.,
palate driven), more care need to be taken. So, for 8-bit images only the grey images are
recommended for data hiding [2].
Three different aspects in information hiding systems contend with each other:
capacity, security, and robustness. All steganographic methods have to comply be applied
with a few basic requirements (i.e., invisibility, payload capacity, robustness against
statistical attacks, robustness against image manipulation, independent of file format, and
unsuspicious files [3].
2. RELATED WORK
Hiding data is the process of embedding information into digital content without
causing perceptual degradation [4]. In data hiding, three famous techniques can be used.
They are watermarking, steganography and cryptography. Steganography is defined as
covering writing in Greek. It includes any process that deals with data or information
within other data. According to Lou et al. [5], steganography is hiding the existence of a
message by hiding information into various carriers. The major intent is to prevent the
detection of hidden information. Research in steganography technique has been done
back in ancient Greek where during that time the ancient Greek practice of tattooing a
secret message on the shaved head of a messenger, and letting his hair grow back before
sending him through enemy territory where the latency of this communications system
was measured in months [6]. However, the majority of the development and use of
computerized steganography only occurred in year 2000 [7]. There are several
steganography techniques used for hiding data such as batch steganography, permutation
stehanography, least significant bits (LSB), bit-plane complexity segmentation (BPCS)
and chaos based spread spectrum image steganography (CSSIS).
3. PROPOSED METHODS FOR HIDING IMAGE IN IMAGE
3.1 4 bit data hiding method
Each pixel contains 8 bits, the right most bit is Least Significant Bit (LSB) and left
most bit is (Most Significant Bit) MSB. Four bit data hiding method, which embeds
first four MSB bits (MSB,MSB-1,MSB-2,MSB-3) of secret image into last four LSB
bits (LSB, LSB+1, LSB+2,LSB+3) of cover image. So last 4 bits of cover image is
replace with first four bits of secret image. Now next pixel of cover image is taken
and again 4 MSB bits of next pixel of secret image is inserted into 4 LSB bits of cover
image.
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3. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN
0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 1, January- February (2013), © IAEME
Cover image
Pixel 1 Pixel 2 Pixel 3
1 0 1 1 0 0 1 1 1 1 0 1 0 1 1 0 0 1 0 0 1 0 0 1
LS LS LS
LS
B+ B+ B+
B
3 2 1
Secret image
Pixel 1 Pixel 2 Pixel 3
1 0 0 0 0 0 1 1 0 1 0 1 1 1 0 0 1 1 0 0 1 1 0 0
MS MS MS MS
B B-1 B-2 B-3
Stego image
Pixel 1 Pixel 2 Pixel 3
1 0 1 1 1 0 0 0 1 1 0 1 0 1 0 1 0 1 0 0 1 1 0 0
Fig.1. Data hiding process using 4 bit method
In this method only 4 MSB bits of each pixel of secret image is considered. Because
of Lower bits of pixel is not contain more information here we omit remaining four bits
(LSB, LSB+1, LSB+2, LSB+3) of secret image. The data to be hidden is converted to
binary form. In Fig.1 gray shad shows that the last 4 LSB bit of cover image is replace
with first 4 MSB bits of secret image. Image processing fundamental said that (‘LSB
contain less information’), so if we change LSB data it not disturb the quality of image. In
proposed method we omit last 4 bits LSB of each Pixel from secret image. Now next
pixel of cover image is taken for data hiding. The manipulation of the three bit alters the
color of the pixel, but this manipulate change cannot easily be perceived by the human
eye.
3.2 6 bit data hiding method
Six bit data hiding method embeds first three MSB bits (MSB, MSB-1, MSB-2) of
secret image into last three LSB bits (LSB, LSB+1, LSB+2) of cover image. Again three
bits of secret image (MSB-3, MSB-4, MSB-5) is stored in 3 LSB bits of next pixel of
cover image. So we are hiding total six MSB bits of secret image into cover image. Cover
image embeds three bit data in each pixel byte. The data to be hidden is converted to
binary form. In Fig.2 gray shad shows that the last 3 LSB bit of cover image is replace
with first 3 MSB bits (1, 0, 0) of secret image. From MSB-3, next 3 bits (0, 0, 0) from
Pixel 1 of Secret image is stored into 3 LSB bits of cover image Pixel 2. In proposed
method we omit last 2bits LSB of each Pixel from secret image.
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4. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN
0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 1, January- February (2013), © IAEME
Cover image
Pixel 1 Pixel 2 Pixel 3
1 0 1 1 0 0 1 1 1 1 0 1 0 1 1 0 0 1 0 0 1 0 0 1
LS LS
LS
B+ B+
B
2 1
Secret image
Pixel 1 Pixel 2 Pixel 3
1 0 0 0 0 0 1 1 0 1 0 1 1 1 0 0 1 1 0 0 1 1 0 0
MS MS MS MS MS MS
B B-1 B-2 B-3 B-4 B-5
Stego image
Pixel 1 Pixel 2 Pixel 3
1 0 1 1 0 1 0 0 1 1 0 1 0 0 0 0 0 1 0 0 1 0 1 0
Fig.2. Data hiding process using 3 bit method
4. PSNR CALCULATION
We then tested the algorithm using the PSNR (Peak signal-to-noise ratio). PSNR is a
standard measurement used in steganograpy technique in order to test the quality of the stego
images. The higher the value of PSNR, the more quality the stego image will have. If the
cover image is C of size M × M and the stego image is S of size N × N, then each cover
image C and stego image S will have pixel value (x, y) from 0 to M-1 and 0 to N-1
respectively. The PSNR is then calculated as follows:
ࡾ૛ ∑ ሾࡵ ሺ࢓,࢔ሻିࡵ ሺ࢓,࢔ሻሿ૛
ࡼࡿࡺࡾ ൌ ૚૙ ‫ ܏ܗܔ‬૚૙ ቀࡹࡿࡱቁ Where ࡹࡿࡱ ൌ ࡹ,ࡺ ૚ ࡹ‫ ࡺכ‬૛
Note that R is the maximum possible pixel value of the images. For example, if the
pixels are represented using 8 bits per sample, then the R value is 255. If the stego image has
a higher PSNR value, then the stego image has more quality image.
5. RESULTS
5.1. 4 bit data hiding method
Fig. 3 shows the application of this method. We have cover image as lena
(size: 512x512) and secret image as cameraman (size: 256x256). Fig 3 shows stegno
image after hidden image stored in cover image. We get index 143 (at location X=32,
Y=100) for cover image while we get index 138 (at location X=32, Y=100) for stegno
image i.e. index is changed. Also we get PSNR is equal to 38.41 dB.
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5. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN
0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 1, January- February (2013), © IAEME
Fig: 3 Four bit data Hiding Method Results
5.2. 6 bit data hiding method
Fig: 4 Six bit data Hiding Method Results
Fig 4 shows the application of this method. Once again we select lena as cover image
and cameraman as secret image. And execute the algorithm. As shown in Fig 4 we get
index 143 (at location X=32, Y=100) for cover image while we get index 141 (at location
X=32, Y=100) for stegno image i.e. index is changed. Also we get PSNR is equal to
41.38 dB. We get better quality of stego image compare to 4 bit method since we are
using 3 bits to embed data. Also the quality of received image is better than that of 4 bit
method because 6 bits of original image is used instead of 4 bits.
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6. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN
0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 1, January- February (2013), © IAEME
6. CONCLUSION
Results indicate that 6 bit data hiding method perform better than 4 bit data hiding
method. We have less data hiding capacity in 6 bit data hiding method but at the same time
we get better stego image & higher PSNR. When applying 6 bit data hiding method on each
byte of a 24-bit image, nine bits can be encoded into each pixel (because each pixel is
represented by three bytes). Also for 8-bit image, 3 bits can be encoded into each pixel. In
this method any changes in the pixel bits will be barely visible to the human eye.
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