| Summary: | 碩士 === 真理大學 === 資訊工程學系碩士班 === 100 === In order to transmit information safely over Internet, techniques of data hiding has been proposed. These techniques are to embed the secret data into the usual and insignificance multimedia. If a digital image is served as a message carrier, the one for carrying data is called as the cover image and another that carried data is called as the stego image. In which, the quality of the stego image must be good so that malicious attackers cannot detect the existence of secret. Data hiding techniques can be categorized into reversible and non-reversible data hiding. The major difference between them is that the former can restore the image to the origin after secret data extracting procedure. Subsequently the restored image can be used at specific applications, such as medical, military and satellite image analysis. In 2006, Ni et al. proposed a reversible data hiding algorithm based on histogram shifting. Their algorithm can produce an acceptable quality, but the payload of secrets is limited. This Thesis proposed a reversible data hiding method based on integer residue number system (RNS) in order to increase the payload. Further, we also applied the image clustering method, which proposed by Tsai and Chan, to divide images into several non-overlapping clusters of distinct size for embedding secret data, and observed the relation between the payload and image quality (PSNR). Finally, we combined the advantages of different expansion and histogram shifting to improve our method with good quality and high payload.
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