A high-capacity and robust steganography algorithm for quantum images

Abstract

The improved flexible representation of a quantum image (IFRQI) employs an effective method to encode grayscale image information in a normalized quantum state vector, which allows for accurate retrieval of image information through projective measurements. In this paper, we propose a high-capacity and robust steganography algorithm based on the IFRQI model. We embed the grayscale information of a 2n×2n sized secret image in a 2n+1×2n+1 sized cover image using controlled rotations. The secret image is divided into four image planes, each with a bit depth of 2. For each image plane, an array of angle values encoding the 2-bit color information is prepared. The encoded information is then embedded in the IFRQI state of the cover image using controlled rotations determined by the key K, which is only known to the operator. The secret image extraction algorithm is the inverse process of the embedding algorithm, which requires the inverse key K′. Analyses of the embedding capacity, time complexity, and visual effects reveal that the proposed steganography algorithm is comparable with some state-of-the-art algorithms.