Reversible Data Hiding Scheme for Images Using Gray Code Pixel Value Optimization

Abstract

Steganography is a technique that allows confidential data to be delivered securely by embedding the data into cover digital media. In this paper, we propose a simple steganography method for cover gray images with high embedding capacity. The secret pixels are not directly embedded into the cover image by a k-bit LSB substitution method with k in the range [1, 4], but can be extracted from stego image by calculating the Canonical Gray Code (CGC) for the correct number of LSBs known only to sender and receiver. The bit embedding process is performed to minimize the influence of the embedded bits on the pixel intensity of the stego-image and limit the possibility of human perception to follow the distortions of the original image.This effect was achieved by considering virtual embedding of secret bits in canonical Gray code (CGC) calculated for the desired number of n bits (k < n ≤ 8) and optimally adjusting the CGC code to the embedded secret bits, and to the original pixel value of the cover image. The paper, in its experimental part, compares the effectiveness of the proposed method with other techniques. For the results verification, peak signal-to-noise ratio (PSNR), mean square error (MSE), and structural similarity index (SSIM) are calculated.