在這篇論文中，我們提出了一個新穎且安全，用於灰階影像中嵌入秘密資料的隱像學方法。嵌入的過程裡，影像首先被切割成多個不重疊的區塊。每個區塊中的像素，則被區分為不可改變像素和可改變像素。接著，計算每個區塊中的不可改變像素的平均灰階值： 。藉由計算可改變像素的灰階值與 之間的差值，來判斷此一可改變像素的變動量。較大的差值會嵌入較多的秘密資料。我們修改可改變像素的灰階值，並將其重新設定為含有秘密資料的灰階值。但是，並非所有的可改變像素皆可適用於我們的方式。有些可改變像素在經過修改之後，有可能會在解析時產生錯誤的結果。我們方法中的嵌入以及解析程序，可以自動的偵測並排除有可能發生錯誤的可改變像素。因此，並不需要多餘的空間來記錄會發生錯誤的可改變像素的位置。由實驗結果得知，我們的方式可以在影像中嵌入資料，但是並不會造成可被察覺的破壞。

We have proposed a novel and secure steganographic method for embedding secret data into a gray scale image in this thesis. In the embedding process, the image is partitioned into non-overlapping blocks. The pixels in a block are classified into unchangeable pixels and changeable pixels. The average of the gray values of unchangeable pixels in each block is calculated as . The embedded amount of data for each changeable pixel is determined by the difference between and the gray value of the changeable pixel. A larger difference embeds a higher amount of secret data. We modify the gray value of a changeable pixel and reset a new gray value with secret data embedded. But, not all the changeable pixels are appropriated for embedding secret data. The gray values of some changeable pixels may cause wrong extraction if they were used in embedding. We have two fault potential checking processes which execute both embedding procedure and extracting procedure to automatically detect and discard fault potential changeable pixels. Therefore, no extra space is needed for recording the positions of the fault potential changeable pixels. The experimental results show that we can embed secret data into an image without noticeable distortion.

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