30-07-2012, 02:47 PM
Hiding data in images by simple LSB substitution
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Abstract
In this paper, a data hiding scheme by simple LSB substitution is proposed. By applying an optimal pixel adjustment
process to the stego-image obtained by the simple LSB substitution method, the image quality of the stego-image can be
greatly improved with low extra computational complexity. The worst case mean-square-error between the stego-image and
the cover-image is derived. Experimental results show that the stego-image is visually indistinguishable from the original
cover-image. The obtained results also show a signi7cant improvement with respect to a previous work.
? 2003 Pattern Recognition Society. Published by Elsevier Ltd. All rights reserved.
Introduction
Data hiding is a method of hiding secret messages into
a cover-media such that an unintended observer will not
be aware of the existence of the hidden messages. In this
paper, 8-bit grayscale images are selected as the covermedia.
These images are called cover-images. Cover-images
with the secret messages embedded in them are called
stego-images. For data hiding methods, the image quality
refers to the quality of the stego-images.
In the literature, many techniques about data hiding have
been proposed [1–5]. One of the common techniques is
based on manipulating the least-signi7cant-bit (LSB) planes
by directly replacing the LSBs of the cover-image with the
message bits. LSB methods typically achieve high capacity.
Optimal pixel adjustment process
In this section, an optimal pixel adjustment process
(OPAP) is proposed to enhance the image quality of
the stego-image obtained by the simple LSB substitution
method. The basic concept of the OPAP is based on the
technique proposed in Ref. [7].
Let pi , p
i and p
i be the corresponding pixel values of
the ith pixel in the cover-image C, the stego-image C obtained
by the simple LSB substitution method and the re-
7ned stego-image obtained after the OPAP. Let i =p
i −pi
be the embedding error between pi and p
i . According to the
embedding process of the simple LSB substitution method
described in Section 2, p
i is obtained by the direct replacement
of the k least signi7cant bits of pi with k message bits,
therefore,
Conclusion
In this paper, a data hiding method by simple LSB substitution
with an optimal pixel adjustment process is proposed.
The image quality of the stego-image can be greatly improved
with low extra computational complexity. Extensive
experiments show the eLectiveness of the proposed method.
The results obtained also show signi7cant improvement than
the method proposed in Ref. [8] with respect to image quality
and computational eOciency.