05-03-2013, 02:17 PM
A PAPER PRESENTATION ON 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 significant improvement with respect to a previous work.
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 cover media. 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 significant bit (LSB) planes by directly replacing the LSBs of the cover-image with the message bits. LSB methods typically achieve high capacity.
Wang et al. [6] proposed to embed secret messages in the moderately significant bit of the cover-image. A genetic algorithm is developed to find an optimal substitution matrix for the embedding of the secret messages. They also proposed to use a local pixel adjustment process (LPAP) to improve the image quality of the stego-image. Unfortunately, since the local pixel adjustment process only considers the last three least significant bits and the fourth bit but not on all bits, the local pixel adjustment process is obviously not optimal. The weakness of the local pixel adjustment process is pointed out in Ref. [7]. As the local pixel adjustment process modifies the LSBs, the technique cannot be applied to data hiding schemes based on simple LSB substitution.
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 effectiveness of the proposed method. The results obtained also show significant improvement than the method proposed in Ref. [8] with respect to image quality and computational efficiency.