Robust and high capacity image steganography technique using spiral-walk inter-block DCT coefficient differencing

Steganography conceals secret information within the cover image so that its presence cannot be detected. Embedding capacity, imperceptibility, and security are three important aspects of a steganographic technique. The paper proposes a new algorithm for concealing binary data in grayscale images by dividing the host image into \( 8 \times 8 \) $8\times 8$ DCT block, and in each block, four embedding locations are selected to embed 4 bits of secret message, increasing the cover image’s embedding capacity. The algorithm computes the difference between the DCT coefficients at the same position of two adjacent blocks to embed the secret bits into the cover image. Furthermore, various steganalysis techniques such as median filtering, gaussian noise, salt& pepper, chi-square, and histogram analysis were performed to check the robustness of the proposed method. The result of the proposed algorithm constructs a stego image with a PSNR of 51.3678 dB, which is higher than that of the existing steganography techniques.