Exploring homogeneity index modification on dual-HDR-image-based reversible data hiding

Dual-image-based reversible data hiding refers to generating two output images after a secret message has been embedded in an original image according to specific embedding rules. This type of reversible data hiding has a relatively high embedding capacity and improved message security. However, most existing algorithms are applied to grayscale images, and the best of our knowledge, no studies have investigated their application to high-dynamic-range (HDR) images. This paper proposes the first dual-HDR-image-based reversible data hiding algorithm featuring homogeneity index modification. First, according to the parity of the three color channel values \(R\) $R$ , \(G\) $G$ , and \(B\) $B$ of each pixel in the original image, the threshold value is used to generate two intermediate pixels, both with even values for all three color channels, for message embedding. The data embedding method called homogeneity index modification can then be effectively incorporated. In addition, image subdivision is employed to improve the embedding capacity further, and message security is enhanced by adopting a multiple-base notational system. Each original pixel value can be recovered quickly by averaging the two corresponding pixel values from the two output images. Extensive experimental results demonstrate the feasibility of the first dual-HDR-image-based reversible data hiding algorithm proposed in this paper, which features a relatively high embedding capacity and improved message security.