| Summary: | 碩士 === 朝陽科技大學 === 資訊管理系碩士班 === 92 === Digital watermarking techniques emerged in around 1992 and they received little attention at the beginning. When more and more researchers pay attention to this issue, more interesting methods of embedding information in multimedia were developed. Among various applications of watermarking, image authentication tries to embed information in order to verify if the image content is tampered with. In this research, an image authentication scheme is first proposed, which is able to identify tampered areas in the image, while being able to resist common image processing operations. The image is first divided into equal-sized, non-overlapping blocks, and the average of pixel intensities is calculated for each of such blocks. The differences of the intensity means of the selected block pairs are then computed and embedded back into the image for content authentication.
The algorithm is further improved by incorporating the ability of tamper recovery. In order to achieve a better recovery result, image blocks with more complex contents are further processed such that the details of the image could be emphasized. The experimental results clearly demonstrate that the proposed algorithms are able to detect malicious attacks on the image, very secure, and very robust to common image processing operations.
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