Reversible data hiding has drawn considerable attention in recent years. Reversible data hiding is required and preferable in many applications such as medical diagnosis, military, law enforcement, fine art work and some other authentication issues. A novel reversible data hiding algorithm which can recover the original host image without any distortion from the marked image after the hidden data have been extracted. In this paper, we propose a scheme based on the multilevel reversible data hiding by shift the histogram of two directional difference images. Through the hiding capacity and a joint imperceptibility evaluation, we show that our proposed scheme using the direction selective mechanism could achieve more hiding capacity and keep distortion low. It is proved analytically and shown experimentally that the peak signal-to-noise ratio (PSNR) of the marked image generated by this method versus the original image is guaranteed to be above other methods. The PSNR is much higher than that of all reversible data hiding techniques reported in the literature.

近年來，可回復的資料藏匿技術受到重視，它在許多範疇中廣為使用，像是醫學、軍事影像、具有法律效益問題的影像以及藝術作品，還有其他有關認證或智慧財產權的部份。一個好的可逆資料隱藏方法，可以在無失真的情況下，萃取出藏於加密影像的訊息，同時將藏有訊息的加密影像回復成原始的影像。在這篇論文中，我們提出了一個具方向選擇性的可逆資料藏匿方法，它是利用對兩種不同方向的差值影像直方圖做評估選擇出較適當的藏匿空間，進而作修改的動作達到資料隱藏的目的；在影像品質以及資訊容量的衡量下，可以看到我們利用了針對影像的內容作不同方向的差值比對，藉此達到改善資訊藏匿容量以及提高影像品質的目的。在實驗結果的部份證明在訊雜比(PSNR)遠比其他可回復資料藏匿方法來得高。

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