[[alternative]]Dynamic Information Hiding Technique based on Modulus Function

碩士資訊工程學系[[abstract]]中文摘要 在以往的資訊隱藏技術裡，為了能夠同時達到高影像品質與高機密資料藏量的要求，會對影像像素的特定屬性來設計資訊隱藏的方法，如Yang等作者於2008年提出目前具有最佳效果的資訊隱藏法，就是利用相鄰像素差值來決定每個像素應藏匿的位元數。為了超越目前現存的方法，我們提出的第一個作法是改良自Yang等作者的方法，在某些特定的狀況下能讓我們藏入更多的機密資料，甚至具有更佳的影像品質，但我們也同時發現Yang等作者的方法受限影像像素差值分佈的限制，在同一種參數設定下對於不同影像會產生不同藏量，藏量調整的彈性受到很大的限制。 為了解決上述的問題，我們另外提出兩個新方法，將焦點轉向機密資料的分佈上。在第二個方法裡，我們利用機密表來限制機密資料的變化，使得模數函式不會受到2的冪次方的限制，由於模數的選擇可以比以往更小、更多，自然我們的方法會較現存方法具有更佳的效果與調整彈性。第三個方法則適合高藏量，概念在自動分配給每個像素塊合適的模數，縮小後的模數可以有效的提昇影像品質。本篇論文除了對Yang等作者的方法作改良，也對各種藏量需求分別提出適合的方法，不論影像品質、機密資料藏量、藏量區間調整彈性，我們都可以在適當的參數設定下超越以往的方法。[[abstract]]Abstract Past efforts across information hiding technique(IHT), in order to maintain stegoimage quality and embedding capacity simultaneously, it would be designed by pixel’s property. As Yang et al. (2008) offered that utilizing pixel-value differences to resolute embedding bit number, which has been regarded as the most efficient way for IHT. In order to surpass current expectations, this research will ameliorate the way from Yang et al. (2008) and embed more capacities, even producing better image quality under some particular situations. However, the research find the theoretical limitation from Yang et al. (2008), that is, the way of IHT seemed to limited by pixel-value differences distribution and the capacity would be highly limited and produced different ways when it is in the same parameter setting. That’s mean the flexibility of adjusting capacity are restricted. In order to solve the above limitation, this research will focus on secret data distribution. Then, this research uses secret table to limit a change of secret data, which modulus function will not limit by power of 2. Due to there will produce more modulus selection than before, obviously, the support results will be concerned more flexible and efficient. Thirdly, further supporting method comes from distribute each block proper downsize modulus, it designed for high embedding capacity. In this article, there will be offer proper methods and improvement from above expectations basing on factors under appropriate setting environment