Robust Image Steganography Against General Downsampling Operations With Lossless Secret Recovery

Resisting the operations in lossy channels is a challenge for image steganography. In this article, we propose a novel robust steganographic method to resist the image downsampling operation. Unlike the existing schemes, our method guarantees lossless secret recovery from the stego-image after general image downsampling operations, which considers the undetectability of the stego-images on both sides (sender and receiver) of the lossy channel. We first downsample the cover image to get its downsampled version on the receiver side, and select a set of embeddable pixels (i.e., the pixels that can be modified for data embedding) from the downsampled image. Then, we generate a stego-image on the receiver side (termed as the receiver stego-image) such that the distortion caused by the data embedding is minimized. Based on the receiver stego-image, we modify the cover image to produce the stego-image on the sender side (termed as the sender stego-image). The modification takes the embedding cost into account and makes sure that the downsampled version of the sender stego-image produces the same embeddable pixels as the receiver stego-image. Experimental results show that our method performs significantly better than the existing schemes in terms of robustness and undetectability for resisting general image downsampling operations.