不同於傳統的資料隱藏技術，可回復式資料隱藏技術可以將隱藏的資料取出後得到原始影像內容而不會有任何的失真。在本篇論文中，我們將提出一套植基於區塊式的高品質可回復式資料隱藏演算法。在本方法中，首先將影像切割成指定大小的區塊，利用鄰近區塊的資訊估計目標區塊的邊方向性，進而依照該方向性來進行差異擴張法達到資料隱藏的效果。根據在數張常用的實驗影像上的實驗結果顯示，在相同的隱藏資料量下，所提出的植基於區塊式的高品質可回復式資料隱藏演算法較過去所提出的區塊式之可回復式資料隱藏演算法有著較佳的影像品質。

Different from the conventional data hiding techniques, the reversible data hiding technique can recover the original image without any distortion after extracting the hidden data. In this thesis, a new quality-efficient block-based reversible data hiding algorithm is presented. In the proposed algorithm, we divide an image into a set of blocks with a specific size. Then, the edge direction of the target block can be estimated by its neighboring blocks. According the estimated edge direction, we can embed the hidden data by the difference expansion scheme. By experimenting on some typical test images, the results demonstrate that under the same embedding capacity, the proposed data hiding algorithm has better marked image quality than the previously published block-based reversible data hiding algorithm.

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