## 1 Introduction  
Authentication preservation with sensors and related applications have emerged as an important research field in recent years [1-4]. Among the authentication schemes, reversible data hiding can be considered as an effective means in this field. Reversible data hiding, also referred to as lossless data hiding or reversible watermarking, has been a newly developed branch and an interesting watermarking research topic [5,6]. Figure 1 outlines the scenario presented in this paper. Suppose that the cover media for secret transmission of data are the digital images, denoted by \(\mathbf{X}\) in Figure 1(a). With the term \"reversibility\", at the encoder, the user-defined secret, denoted by \(S\) in Figure 1(a), should be embedded into the cover image \(\mathbf{X}\) by the reversible data hiding method proposed by algorithm designers. After accomplishing the embedding process, the image containing the secret information, denoted by \(\mathbf{X}^{\prime}\), and the side information for making decoding possible, denoted by \(K\), should be transmitted to the decoder. The size of \(S\) can be as large as possible, while the size of \(K\) should be as small as possible. And at the decoder in Figure 1(b), by using the received \(\mathbf{X}^{\prime}\) and \(K\), the reconstructed image \(\widetilde{\mathbf{X}}\) and the extracted secret \(\widetilde{S}\) can be recovered. Due to reversibility, \(\widetilde{\mathbf{X}}\) and \(\widetilde{S}\) should be identical to their counterparts of \(\mathbf{X}\) and \(S\), respectively. Therefore, how to design an effective algorithm for reversible data hiding is an interesting task in both research and application.  
There are requirements for designing a good reversible data hiding algorithm [7-9]. Four major requirements are: (a) the output image quality, called the imperceptibility, (b) the number of bits that can be hidden into the cover image, named the capacity, (c) the side information that is necessary for performing data extraction at the decoder, and (d) the ease of implementation of the algorithm. And we observe that these requirements have some correlations or conflict with the others. For instance, embedding more capacity would lead to the more deterioration to the cover image, and hence the degradation result in imperceptibility of the output image. From the viewpoint of practical applications, less overhead is greatly required. Therefore, how to develop a reversible data hiding algorithm that can hide more capacity, produce the output image quality with acceptable imperceptibility, and generate as little side information as possible are much required, and these are the major contributions of this paper.  
Figure 1: **(a)** The structure for reversible data embedding. **(b)** The structure for reversible data extraction.  
This paper is organized as follows. In Section 2, due to the ease of implementation, we present fundamental descriptions of conventional histogram-based reversible data hiding algorithm. Then, in Section 3, for making good use of the characteristics of the cover image, we take the quadtree decomposition into account and look for the integration with the algorithm presented in Section 2. Simulation results are demonstrated in Section 4, which suggest the applicability of the algorithm and the integration proposed over conventional schemes. Finally, we conclude this paper in Section 5.