| Summary: | 碩士 === 國立屏東大學 === 資訊工程學系碩士班 === 103 === With the explosion of Internet technology in recent years, a lot of creators worry and fear personal portfolio suffered illegal dissemination with used. How to authenticate the original image, not only prevent an illegal hacker attacks but also recover a tampered image. Therefore, the protection of a digital image is becoming important.
In this thesis, a novel watermarking method based on standard deviation is proposed for image authentication and recovery. In the embedding process of the proposed method, firstly the original image is divided into non-overlapping blocks and each block is decomposed by discrete wavelet transform (DWT). Next, the low-frequency coefficients of each DWT block is used to calculate the standard deviation which can be embedded as the feature watermark. In addition, the first two bits of the low-frequency coefficients are used as recover watermark. Finally, experiment results show that the proposed method compared with recent researches, obtains a better PSNR value and image quality after recovery of the tampered regions.
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