High-capacity PVO-based reversible data hiding scheme using changeable step size
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High-capacity PVO-based reversible data hiding scheme using changeable step size Kui Zhou1 · Ye Ding1 · Weihong Bi1 Received: 21 June 2019 / Revised: 2 July 2020 / Accepted: 16 July 2020 / © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Reversible data hiding (RDH) algorithm based on pixel-value-ordering (PVO) has received widespread attention because of its excellent performance. PVO algorithm divides the host image into non-overlapped equal-sized blocks, then achieves data embedding by modifying the maximum and minimum values of each block. Every pixel block can be a host of watermark data, so the smaller number of pixel blocks limit the embedding capacity (EC). In our work, a novel PVO with changeable step size (CPVO) is presented which can choose suitable step size based on the number of watermark data bits, even that allow one block to overlap other ones. Take the block size 2 × 2 as an example, we can set step size 2 × 1 or another one in CPVO. Consequently, with a block selection skill based on the noise level (NL) of a pixel block, CPVO can embed more hidden data bits into a host image. Compared to the original PVO-based schemes, experimental results show that our proposed scheme increases the EC by 2 ∼ 3 times, and the marked image quality keeps much higher, even outperforms some other state-of-the-art works in some test images. Keywords RDH · PVO · Changeable step size · Block selection
1 Introduction Reversible data hiding (RDH) has been attracting more attention from researchers in the field of images. RDH is a technique to embed watermark data into a host image with slight modification on its pixels. It requires that decoder can extract the embedded data from a marked image correctly and the original image is not destroyed [2]. One of the applications Weihong Bi
[email protected] Kui Zhou [email protected] Ye Ding [email protected] 1
School of Mathematical Sciences, Zhejiang University, Hangzhou, 310000, People’s Republic of China
Multimedia Tools and Applications
is to prevent important information from being leaked or stolen, such as copyright protection [17, 21, 38], property certification [5, 12, 37], medical digital images [15], real-time videos [14], etc. An excellent RDH algorithm should keep the distortion as low as possible while providing adequate embedding capacity (EC) [7]. Many RDH algorithms have been proposed so far. Early methods concentrated on lossless compression mainly [3, 4, 7, 32]. These initial methods usually can only provide much lower EC and the marked image has a bigger distortion. After then, Tian first proposed a technique called difference expansion (DE) [34]. The basic idea of DE is to expand the difference value of neighboring pixel values to embed data. And Tian improved the method in [35]. Afterwards, the technique of DE got further improvements in the paper [1, 13, 31]. Later on, the technique prediction-error expansion (PEE) was proposed by Thodi and Rodriguez [33]. Unlike DE, PEE utilizes more neighboring pixel values and gets
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