An Improved Steganographic Method Based on Least-Significant-Bit Substitution and Modulus Pixel-Value Difference

Abstract

An image-domain steganographic method based on a least-significant-bit (LSB) substitution and modulus pixel-value differencing (MPVD) is proposed to hide data in greyscale images. This is a modification of the hybrid LSB/PVD (HLSB/PVD) method proposed by Jung [1]. The cover image is first partitioned into 3 × 3 sized blocks, followed by 5-bit LSB substitution on the central (base) pixel. The differences between the remaining and base pixel values are then computed. HLSB/PVD is applied, with the LSB method used to divide the pixels into higher and lower bits. Data embedding in the lower and higher bits is conducted using 2-bit LSB substitution and MPVD, respectively, leading to a high embedding capacity while retaining an adequate quality in a stego-image.
Embedding experiments conducted with Lena, Baboon, Goldhill, Boat, House, Airplane, Tiffany, and Peppers showed a mean embedding capacity of 1,087,274 bits, (3.46% higher than that of the HLSB/PVD method). At an embedding rate of 4.14 bpp, the peak signal-to-noise ratio of our method is 31.98 dB. Our method improves the embedding capacity and maintains the imperceptibility.