Abstract
A modified multiway pixel-value differencing method for image steganography using general quantization ranges of pixel pairs’ difference values is proposed, where the widths of the quantization ranges are not limited to be powers of two. The method can be employed to embed a secret message into a cover image with a higher embedding rate. The cover image is partitioned into non-overlapping complete or incomplete blocks using <inline-formula> <tex-math notation="LaTeX">$1 \times 3$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$2 \times 2$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$2 \times 3$ </tex-math></inline-formula>, or <inline-formula> <tex-math notation="LaTeX">$3 \times 3$ </tex-math></inline-formula> block templates. The message bitstream, whose bit positions are randomized in advance by use of a random number generator, can be embedded in the resulting blocks. More specifically, one pixel in each block is set as a shared pixel, and the least-significant-bit substitution method with the optimal pixel adjustment process is employed to embed message bits into the shared pixel. Next, the shared pixel in the block is combined with each remaining pixel to form a pixel pair, which is then utilized to embed message bits by a new pixel-value differencing method. Also, the use of non-power-of-two range widths is accomplished by a multiple-based number conversion mechanism, and the shared pixel in each block, as well as each related pixel pair whose two grayscale values pass a falling-off-boundary check, are used to embed the digits of the resulting multiple-based number. The experimental results show that the embedding rates yielded by the proposed method are higher than those yielded by existing multiway pixel-value differencing methods. The stego-images resulting from embedding secret messages retain good image quality, and the RS steganalysis process cannot detect the presence of the embedded secret messages.
Highlights
Steganography [1,2,3,4] and watermarking [5,6] techniques are important research topics in multimedia security
Wu [16] proposed the general pixel-value differencing (GPVD) method based on the PVD [8] method, but the quantization range used is not limited to the power of two
This paper proposes a general and modified multiway pixelvalue differencing data hiding method with a quantization range not limited to the power of two
Summary
Steganography [1,2,3,4] and watermarking [5,6] techniques are important research topics in multimedia security. The least significant bit (LSB) substitution method [7] and the pixel-value differencing (PVD) hiding method [8] are both types of embedding messages in the spatial domain of images. The central pixel of the block is first embedded with secret messages by the LSB substitution method with OPAP [9] technique. Wu [16] proposed the general pixel-value differencing (GPVD) method based on the PVD [8] method, but the quantization range used is not limited to the power of two. This paper proposes a general and modified multiway pixelvalue differencing data hiding method with a quantization range not limited to the power of two.
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