本論文增加浮水印位元嵌入位置的選擇，來改善在某些浮水印位元的嵌入情況下，會產生受保護數位影像品質大量失真的問題，並且可以不用調整原始數位影像的資訊，就能夠代表浮水印。另一方面，經由新門檻值的設定，使其可以精確且適當的調整原始數位影像的資訊來增加浮水印的強健性。

經過實驗的分析與比較結果可以得知，所提出的改良浮水印方法在受保護數位影像品質與浮水印的強健性皆能獲得有效的提升，並且在浮水印的安全性方面，提出的改良浮水印方法中的浮水印位元的嵌入位置比原浮水印方法中的浮水印位元的嵌入位置還要來的更多，使得浮水印被破解的可能性更為稀少。

In this paper, we proposed a robust watermarking algorithm for color images. The proposed algorithm includes a maximum difference selection of the wavelet-trees and an improved wavelet-tree embedding scheme. We increase the number of the watermark embedding positions to reduce image distortion. In some embedding cases, the proposed method does not need to adjust the original image information, but it can represent the watermark embedding. On the other hand, through the new threshold setting, it can accurately and appropriately adjust original image information to increase the robustness of the embedded watermark.

Experimental results show that the proposed method can effectively increase both the watermarked image quality and the watermark robustness. In the aspect of watermark security, the proposed method has more positions to embedding than the original method, which results in a more secure watermark.

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