- 學位論文
具有可逆式資料隱藏功能的影像對比度增強之研究
On the Study of Image Contrast Enhancement with the Capability of Reversible Data Hiding
摘要
藉由線性轉換的觀念將一組像素做轉換使得轉換後的像素與原來的像素有對比增強的效果，並將秘密訊息藏入轉換後的像素的最低位元中，達到資料隱藏的效果。傳送端，藉由多次線性轉換的方式增加可藏的秘密訊息量及增強對比度；接收端，經過影像還原的步驟可以把全部的秘密訊息提取出來，並將原始的影像值還原。這裡，這種技術被稱為“可逆式對比轉換” 本論文將會對兩種可逆式對比轉換作探討，第一種是廣義式一維對比轉換，由先前文獻上論文所提供的對比轉換方程式，我們可以找出其他種的對比轉換方程式；第二種是二維對比轉換，藉由一維的對比轉換，我們可以列做完一次轉換後行再做一次對比轉換，就可以得到二維轉換方程式。
並列摘要
The concept of linear transformation is used to convert a pair of pixels so that the converted pixels have the effect of contrast enhancement while compared with the original pixels, and the secret information bit can be hidden into the LSB (Least Significant Bit) of the first pixel in the pair of converted pixels simultaneously. In the sending end, it can further increase the hidden quantity of secret information and enhance the degree of contrast by means of multiple transformations. In the receiving end, all the secret information can be extracted completely and the original image can be restored perfectly without any distortion during the image restoration step. Here, such a technique is called “reversible contrast mapping”. This thesis will discuss two kinds of reversible contrast mapping. The first one is the generalized one-dimensional contrast mapping. From the contrast mapping equations provided by the previous papers in the literature, we can find other kinds of contrast mapping equations; the second one is the two-Dimensional contrast mapping which is based on the one-dimensional contrast mapping sequentially applied to the row pixels, and then to the column pixels.