A novel technique for image steganography based on Block-DCT and Huffman Encoding

TL;DR

This paper introduces a new image steganography method using Block-DCT and Huffman encoding, achieving high capacity, good invisibility, and security by embedding secret data in frequency domain coefficients.

Contribution

It proposes a novel combination of Block-DCT and Huffman encoding for improved image steganography with enhanced capacity and security.

Findings

High embedding capacity demonstrated.

Stego images maintain high PSNR indicating good invisibility.

Security is enhanced through Huffman encoding and secret key dependence.

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 x N is divided into no joint 8 x 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.