偽裝術（Steganography）與可回復式資料隱藏（Reversible Data Hiding, RDH）是廣泛用於資料隱私保護以及確保資料機密性的技術。在這類型的研究中，我們致力於提升與追求偽裝影像的不可察覺性（Imperceptibility）、不可檢測性（Undetectability）、高嵌入容量（Embedding Capacity, EC)以及優良的偽裝影像品質（Image Quality）。在本研究論文當中，我們針對 Steganography 以及 RDH 領 域提出了兩種基於 Exploiting Modification Direction (EMD)的技術，以提升其嵌入容量、影像品質並確保其不可察覺性。在第一項技術中，我們提出了一種基於時鐘調整模型（Clock Adjusted Model, CAM）的參數化多層式 EMD（Parameterized Multilayer-EMD with Clock-Adjusted Model, PMEMD-CAM）應用於 Steganography；在第二項技術中，我們提出了一種基於可控制的泛化式 EMD 應用於基於影像插值法的可回復式資訊隱藏技術（Controllable Generalized EMD on Interpolationbased RDH, CGEMD-IRDH）。這兩項技術皆利用了本研究所提出的 EMD 方法，與現有的最新技術相比，具有更高的嵌入容量與良好的影像品質。根據實驗結果顯示，兩種所提出的技術在資料嵌入容量(EC)與峰值訊號雜訊比（Peak-Signal Noise Ratio, PSNR）方面優於現有的 Steganography 以及 IRDH 研究方法。另一方面，透過安全分析與檢測實驗，結果顯示本研究所提出的兩種技術皆兼備良好的不可檢測性。;Steganography and Reversible Data Hiding (RDH) are widely used techniques for protecting data privacy and ensuring data confidentiality. In such research, the desired attributes always include undetectability, imperceptibility, a high embedding capacity (EC), and excellent image quality for the stego-image. In this paper, we propose two Exploiting Modification Direction (EMD)-based approaches for Steganography and RDH to enhance imperceptibility and EC. In the first approach for Steganography, we propose a Parameterized Multilayer-EMD with Clock-Adjusted Model (PMEMD-CAM); in the second approach, an interpolation-based RDH (IRDH) with controllable generalized EMD (CGEMD-IRDH) is proposed. Both techniques take advantage of the proposed EMD techniques, resulting in a high embedding capacity and good image quality compared to the existing state-of-the-art schemes. Experimental results demonstrate that both of the proposed methods are superior to the existing Steganography and IRDH schemes in terms of EC and Peak-Signal Noise Ratio (PSNR). Furthermore, the results of security analysis indicate the good undetectability of the two proposed methods.
