| Summary: | 碩士 === 大同大學 === 資訊工程學系(所) === 105 === Nowadays, data transmission and stored on internet are very popular, so that data security is an important topic. Cryptography encrypts secret messages as chaos-like cipher-texts which will attract attention of malicious attacker. On the other hand, information hiding embeds secret messages into a cover media in which imperceptibility keeps the secret safe. Information hiding can be applied in the field of intellectual protection, security certification, authorization inspection, use of confidential, information entrainment and many other fields.
Among irreversible information-hiding techniques, many researches based on modulo operations have been proposed. Our researches are also base on modulo operations. We first present an optimal (4, 10)-modulo-operation information-hiding technique, which achieve highest 2.5 data hiding bit rates per pixel and good hiding quality on peak signal to noise ratio. On the other hand, we present an optimal (n, b)- modulo-operation information-hiding technique, which provide hiding b bit rates per n pixels with high hiding quality based on optimal weighted coefficients. Moreover, hiding efficiency in our algorithms are also improved.
Among reversible information-hiding techniques, we modify the procedure of judgment and present a concise algorithm so that we make less decision in more frequent cases. Our algorithm can make two times improvement in efficiency.
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