A novel technique for image steganography based on Block-DCT and Huffman Encoding
Amitava Nag, Biswas S, D. Sarkar · International Journal of Computer Science and Information Technology · 2010
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.