影像認證(Image Authentication)技術在現今科技發展上對於認證影像的正確性與完整性具有非常重要的地位。影像認證技術是利用嵌入的浮水印來偵測影像是否有遭到竄改，並且將遭竄改的影像恢復。所以可以提供影像一個完整的保護。
本論文是使用階層樹集合分割演算法(Set Partitioning in Hierarchical Trees, SPIHT)來產生浮水印，浮水印數量越多則對於竄改偵測(Tamper Detection)及影像恢復(Image Recovery)的效果越好。但相對的，當浮水印數量越多則嵌入浮水印後的影像品質也會越差。所以本論文的研究方向是在有限制浮水印數量下如何提高竄改偵測及影像恢復的能力。
最後，經實驗證明本論文所提出的方法在嵌入浮水印的影像上能符合浮水印的隱藏性(Imperceptibility)及影像觀賞品質。而在SPIHT解碼後的影像上則PSNR平均可以提升2 ~ 3 dB。而在竄改偵測方法上則能夠準確定位出遭竄改的區塊。

Nowadays, the development of the technology of image authentication has taken an important role to verify the correctness and the integrity of image. Using the embedded watermarking to detect whether the image has been tampered, the technology of image authentication is capable of recovering the tampered image so as to provide the better protection for the image.
The paper refers to using SPIHT (Set Partitioning in Hierarchical Trees) to generate watermarking. The more the watermarking is generated, the better the effect of tamper detection and image recovery will be. However, as the more watermarking is produced, the quality of watermarked image becomes worse. Therefore, this paper aims to enhance the ability of tamper detection and image recovery in the condition of the limited number of watermarking.
Finally, this paper experimentally proves that the watermarked image proposed herein complies with the imperceptibility of watermark and the quality of visual image. The SPIHT decoded image can improve the PSNR performance by 2 ~ 3 dB on average. And, the method of tamper detection can precisely position those tampered blocks.

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