AIRCC's International Journal of Computer Science and Information Technology

D. Biswas ¹, S. Biswas ², P. P. Sarkar ², D. Sarkar ², S. Banerjee ¹, A. Pal ¹

Affiliations
1 Academy of Technology, Hoogly – 712121, West Bengal, IN
2 USIC, University of Kalyani, Kalyani, Nadia – 741235, West Bengal, IN

Abstract

This paper is based on a comparative study between different watermarking techniques such as LSB hiding algorithm, (2, 2) visual cryptography based watermarking for color images [3,4] and Randomized LSB-MSB hiding algorithm [1]. Here, we embed the secret image in a host or original image, by using these bit-wise pixel manipulation algorithms. This is followed by a comparative study of the resultant images through Peak Signal to Noise Ratio (PSNR) calculation. The property wise variation of different types of secret images that are embedded into the host image plays an important role in this context. The calculation of the Peak Signal to Noise Ratio is done for different color levels (red, green, blue) and also for their equivalent gray level images. From the results, we are trying to predict which technique is more suitable to which type of secret image.

Keywords

Steganography, Visual Cryptography, Watermarking, LSB Hiding, PSNR.

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A. Nag ¹, S. Biswas ², D. Sarkar ², P. P. Sarkar ²

Affiliations
1 Academy of Technology, Hoogly - 721212, IN
2 USIC, University of Kalyani, Kalyani, Nadia – 741 235, West Bengal, IN

Abstract

Image steganography is the art of hiding information into a cover image. This paper presents a novel technique for Image steganography based on Block-DCT, where DCT is used to transform original image (cover image) blocks from spatial domain to frequency domain. Firstly a gray level image of size M × N is divided into no joint 8 × 8 blocks and a two dimensional Discrete Cosine Transform(2-d DCT) is performed on each of the P = MN / 64 blocks. Then Huffman encoding is also performed on the secret messages/images before embedding and each bit of Huffman code of secret message/image is embedded in the frequency domain by altering the least significant bit of each of the DCT coefficients of cover image blocks. The experimental results show that the algorithm has a high capacity and a good invisibility. Moreover PSNR of cover image with stego-image shows the better results in comparison with other existing steganography approaches. Furthermore, satisfactory security is maintained since the secret message/image cannot be extracted without knowing decoding rules and Huffman table.

Keywords

Steganography, Frequency Domain, DCT, Huffman Coding, Information Hiding.

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