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Title: Histogram and Vector Quantization based Multilevel Reversible Data Hiding Schemes
Authors: Kukreja, Sonal
Supervisor: Kasana, Singara Singh
Keywords: PSNR, MSE, VQ, Histogram;CSED
Issue Date: 30-Jul-2015
Abstract: Data hiding techniques in digital images has been a topic of research for so many years. The role of data hiding is to embed secret data in the cover media at the sender side and retrieve the embedded secret data as well as the cover media at the receiver side. Reversible data hiding techniques are used to recover the cover media from marked media by extracting secret media without any distortion. The main purpose of this dissertation is to improve the hiding capacity of the images while maintaining the PSNR upto a level. In this dissertation, we have proposed three reversible data hiding techniques. The first technique is based on histogram shifting. In this technique, histogram shifting is used to create space for hiding the secret data, where the shifting is done between the peak and minimum points of the histogram of the cover image, hiding the data into the pixels corresponding to the maximum point. This technique is applied first to the cover image and then to the obtained stego images upto a desired number of levels, thus increasing the hiding capacity of the cover image. This technique embeds large amount of secret data while maintaining the visual quality of the stego images. Proposed technique is completely reversible as embedded data is extracted without any loss. Second technique is multilevel reversible data hiding technique based on the blocks of difference image. In this technique, a cover image is divided into non overlapping blocks of equal size and then simple and absolute differences of each block are evaluated. After it, histogram of each absolute difference block is generated and peak negative points of simple difference are replaced into absolute difference blocks at respective positions. Then peak positive and peak negative points of each difference block are used to hide the secret data. Numbers of bits hidden into each positive peak points is one bit only but in negative peak points, more than a bit are hidden which increase the hiding capacity of a cover image. Proposed technique achieves high hiding capacity than existing reversible data hiding techniques while keeping distortion in the marked image low.
Description: MT, CSED
Appears in Collections:Masters Theses@CSED

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